Michael Screen
THE CROWOOD PRESS
First published in 2018 by
The Crowood Press Ltd
Ramsbury, Marlborough
Wiltshire SN8 2HR
www.crowood.com
This e-book first published in 2018
© Michael Screen 2018
All rights reserved. This e-book is copyright material and must not be
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law accordingly.
British Library Cataloguing-in-Publication Data A catalogue record for
this book is available from the British Library.
ISBN 978 1 78500 512 1
Acknowledgements
I would like to give my sincerest thanks to my partner Isabelle for her
invaluable help and encouragement in editing and preparing the text for
submission. I would also like to thank her father Paul for his photography
and exceptional Photoshop skills. Finally, I would like to thank the
countless students, both young and old, who have unwittingly served as
my toy-making guinea pigs over the years.
CONTENTS
INTRODUCTION
1
TIMBERS AND MANUFACTURED BOARDS
2
TOOLS AND MACHINES
3
BASIC MOTION AND MECHANISMS
4
TIPS AND TECHNIQUES
5
PAINTS AND FINISHES
6
THE FANTASTIC FROG
7
THE HUNGRY HOUND
8
THE RETRO ROVING ROBOT TOY
9
THE CRANKY CROCODILE
10
THE ROAMING RAPTOR
11
INDEX
DEVELOPING YOUR OWN DESIGNS
INTRODUCTION
Are you looking to develop your ambition as a toy maker and
craftsperson? You may be an aspirational hobbyist, semi-retired or
retired, an educator, a practising craftsperson or a student looking for
inspiration: this book shares some of my skills and experiences as an
educator, toymaker and craftsperson of over thirty years.
What could be more satisfying than designing and building your own
mechanical timber toys? They make amazing gifts both for children and
for not-so-young family members. Your playthings will be given a name,
and will be cherished, played with, and hopefully passed to a new
generation. They will develop the endearing patination of age and use as
they progress through their lifetime.
Perhaps you lack the confidence to currently develop your own
mechanical toy ideas, or are looking for a challenge to produce more
sophisticated examples. Mechanical toys are the perfect synthesis
between craftsmanship, engineering and artistic expression. You have a
plaything with its own beautiful mechanical action, and sounds that don’t
need batteries or mains electricity to make them function. It is always
fascinating to watch the input motion being converted into walks, wiggles,
shakes, snaps, rattles and rolls. People love to examine them, to try and
unravel the mystery of what is essentially a simple piece of wooden
engineering.
The toy maker has a considerable repertoire of techniques and
materials at their disposal for generating movement and character in a
plaything. Many materials and processes are available, as even a
glancing look at historical toy making will show. People have always used
the indigenous materials and skills available to them, generating a rich
and varied range of toys from different times across the world.
This book focuses on the production of five kinetic wheeled toys
operated by a push-and-pull action, with timber as the primary
construction material. They are not, strictly speaking, automata, which
tend to be remotely operated with a more complex mechanism and
generally operated by a hand-turned crank. The projects in this book use
wheels, cams, cranks and linkages in various combinations to generate
some beautiful mechanical actions when the toy is pushed and pulled.
Mechanical toys require only small amounts of material, such as
offcuts and recycled timber, and can be produced in a relatively small
space. You will also find in this book information on surface finishes,
techniques and treatments to make your toys look amazing. This book
will give you clear, concise, step-by-step instructions to produce five
practical, kinetic toy projects, shown within these covers. Each chapter is
filled with detailed step-by-step illustrated guidelines to produce a well
made, functioning outcome. The book also contains advice and
strategies to help you develop your own confidence and creativity. The
only prerequisites to developing your toy making are access to
rudimentary tools, and a workspace with a stable, secure worktop and
vice.
Finally, timber toy craft production also offers an ethical and aesthetic
antidote to the ruthless blandness and banality of many modern,
massproduced, injection-moulded plastic toys.
CHAPTER TWO
TOOLS AND MACHINES
It is beyond the scope of this book to give an exhaustive list of tools and
processes and how to use them. I am assuming you have at least a
rudimentary understanding of these, so I will itemize the essentials for the
successful toy maker/craftsperson and their workspace.
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Organize your workspace to utilize it efficiently and to make it safe to
work in. Keep the floor clear to avoid tripping, and place things away
carefully to avoid the enormous frustration caused by losing or
misplacing items
Ideally you should have access to good natural or artificial lighting
Learn how to look after your tools! Blunt tools are the most
dangerous, besides causing mistakes in your work
Power tools such as electric routers are a fantastic resource but
require careful practice and use. A razor-sharp cutting tool rotating at
30,000 RPM is a formidable opponent when used incorrectly. Routers
are second only to the angle grinder for hospitalizing craftspeople and
construction workers
Dust extraction and protection are important if you plan on doing a lot
of work. It’s staggering how much wood dust accumulates in a short
space of time, especially when using power sanding tools. At least
wear a face mask or respirator
The most basic need when working materials to form any object is
being able to hold components safely and securely. Toy making
offers the opportunity of working on a relatively small scale but
requires some careful shaping and fitting, which can prove difficult
without a sturdy vice. My advice would be to get a small, used
workbench with a vice, and ideally a portable engineer’s vice (the
type used for holding metal components)
Go back to basics! Be able to work to a line using saws, planes and
files. With one flat surface you have a datum point from which to
make right angles and the three other, square, true edges and
•
•
surfaces. This is especially useful when buying slabs of raw
hardwoods and no access to a planer thicknesser or a table saw.
With confidence you can be much freer and more intuitive by
sculpting and shaping in a more expressive way using chisels, drum
sanders and rotary cutting tools. The projects within this book make
extensive use of drum sanders and rotary cutting tools, which need
some practice to develop confidence. A useful idea is to try out
techniques on a piece of scrap material first
All cutting, abrasion and shaping hand tools have their electric
equivalent, but it is good to be able to do things the low-tech way
before ‘going electric’. The bottom line is that power tools cut out a lot
of drudgery, speed up production and ensure dimensional accuracy
(if done correctly). As a hobbyist, it can be very satisfying to cut and
square up a timber blank occasionally before forming a component,
but the repetition can be mind numbing
Complete fabricating and assembly tasks in the correct order. It’s
extremely difficult to locate and drill a hole accurately in an irregularly
shaped piece of timber. Drill all holes while the workpiece is flat and
easy to hold. Similarly, perform the shaping and fitting stages for
projects explained in this book in the correct order to avoid
complicating tasks unnecessarily. Each project is supplied with a
page of templates which can be pasted on to the timber blanks to
avoid complex marking out. Where a hole is required, refer to the
required drill-bit diameter and centre punch the location to assist the
drill bit to locate the hole accurately. Another example is drilling the
holes for axles while the wheel blank is a square, and therefore easier
to grip in a machine vice.
Useful Power Tools
All power tools are available in a number of sizes and power ratings. As a
general guide, the higher the motor wattage, the more torque the motor
will generate. This will allow faster working and ultimately prolong the
motor’s life. Cheap, small wattage motors burn out too easily and quickly.
The best for the workshop are those that can be bench mounted for the
sake of portability and using a limited space effectively. Bigger,
freestanding versions are available depending on your budget and
workshop size.
The key to acquiring useful tools is to let need direct your purchases.
As mentioned above, aim to buy the most powerful wattage, good quality
motors, as these will give the tool greater torque and resist burning out. If
you are a real purist, continue with hand tools exclusively. Finally, nothing
compares to buying tools and machines with money you have made
selling your own toys or crafts.
For toy making for the hobbyist with limited space and budget, the
following machines are invaluable.
Bench-mounted pillar drill: A number of good models of pillar drill exist
at a very reasonable price. Really cheap power tools have poor quality
motors, which will burn out with excessive use. The pillar drill also allows
a drum sander to be fitted, which is a very efficient abrasive tool.
Bench-mounted bandsaw: The bandsaw is ideal for cutting across the
grain or for ripping work (cutting with the grain) if required. You need
several blades for different tasks when using the bandsaw.
Scroll saw: Again, this can be bench mounted and enables the operator
to cut extremely tight, curved profiles that require little surface finishing
afterwards. Unlike the bandsaw, the scroll saw blade leaves few blade
marks and doesn’t tear the wood fibre – a component cut with a fine
scroll-saw blade needs almost no filing or glass papering. As with
bandsaw blades, different grades of coarseness can be used for cutting
different materials and thicknesses.
Orbital sander or linisher: These tools are fantastic for sanding angles
and chamfers, and can be used with a number of jigs to produce different
diameter wheels with the appropriate production jig. They are also
criminally neglected as the source of many workshop accidents. An 80grit abrasive paper will strip your finger tips and knuckles in an instant.
Look for ones with a guard, feed the workpiece to the abrasive surface in
the right direction, and don’t use too much pressure on the workpiece.
Rotary cutting tools: Several manufacturers offer these tools, with a
bewildering range of cutting tools and attachments for a range of
materials. It is the most versatile and enjoyable tool to use. The best
models are sold with variable speed settings.
Electric router: There isn’t much an experienced router user cannot do
with this machine, but as mentioned earlier, get to know it and practise
safely before letting loose with it. I have a dedicated router set into a
portable table to act as a mini spindle moulder. I once fed the workpiece
in the wrong direction, causing the wooden piece to be propelled at high
speed across the room before embedding itself into the plasterboard wall.
Wood lathe: This lathe is a fantastic resource if you can stretch to it. You
can get very good quality, bench-mounted wood lathes for a reasonable
price. A wood lathe can be used extensively for both toy-making and
furniturebuilding projects.
The timber penguin toys were made on a wood lathe, cut and reassembled to make them
more asymmetrical and lifelike.
CHAPTER THREE
BASIC MOTION AND MECHANISMS
Put simply, a mechanism is a movement and force processor. It converts
one type or direction of motion or force into another, and can amplify or
reduce it, and transmit it to where it is needed. Assembled into a system,
a collection of different mechanisms becomes a machine. All
mechanisms and machines process movement and force. There are four
types or unique directions of movement – linear, reciprocating, rotary and
oscillating – and all mechanisms and mechanical systems process these
directions or combinations of motion and force.
Linear: Movement in a line.
Reciprocating: Backwards and forwards, or up-and-down movement.
Rotary: Movement in a circle.
Oscillating: Movement like a clock pendulum or see-saw.
Examples of movement types and directions. As a toy designer it is good to have a basic
understanding of mechanisms and motion, especially levers, linkages and cam
mechanisms.
Types of Mechanism
A lever is the simplest mechanism used to transfer or process motion and
force. The three classes or types of lever all have a pivot point (or
fulcrum), a load and an effort. There are three types or classes of lever.
Examples of lever showing the three classes or orders of lever.
The robot arms are a class three lever that oscillates when driven by the rotary action of
the wheel. The whole assembly is similar to a treadle linkage used to drive old-fashioned
sewing machines or potters’ wheels.
Linkage Mechanism
A collection of levers assembled together is called a linkage. The head
and neck of the dinosaur toy uses a linkage mechanism to generate the
rise and fall of the head and the accompanying snapping action.
Linkages are some of the most common and versatile mechanisms
available to the toy maker.
Cam Mechanisms
A cam is really a wheel that moves eccentrically or is reshaped to cause
a lever in contact with it to reciprocate or oscillate. The dog’s tail, robot
head and dinosaur head in this book are controlled by eccentric cams. A
cam normally causes a lever called a follower to reciprocate or oscillate.
For the purposes of toy making, gravity causes the follower to return to its
original position before the cycle starts again. A smoother action can be
achieved by placing a compression spring over the follower to keep it in
constant contact with the cam wheel.
There are several cam profiles available, the most useful for kinetic toy
making being the eccentric cam, which is essentially a wheel where the
geometric centre has been off set. The greater the distance of the pivot
point of the cam from the wheel’s true centre, the greater the possible lift
it can generate.
Examples of cam wheels showing different profiles to generate different output motions.
The robot toy’s head reciprocates as it rises and falls on the eccentric cam connected to
the wheel and axle assembly. Gravity causes the follower attached to the head to remain in
constant contact with the eccentric cam without the need for any return springs.
Belt and Pulley
A belt is set within grooves between the drive wheel and the driven
wheel. Speed changes between input and output speed can be achieved
by changing the ratio of the driver to the driven pulley-wheel diameters. A
driven pulley can also be caused to rotate in the opposite direction by
twisting the belt in the middle.
A belt and pulley assembly driven by a small hand crank.
Chain and Sprocket
Toothed wheels or sprockets are driven by an articulated chain in place
which works like the belt in a pulley and belt system. Its advantage is a
greater reduction in slippage or the belt riding off. Small chain and
sprocket kits can be purchased from craft and educational suppliers quite
easily and cheaply.
The toy maker can produce gear wheels using a laser cutter or by buying gearbox kits
from craft and educational suppliers. Complex transmission changes can be achieved by
carefully designing the ratio between driver and driven gears or input and output gears.
Gear Mechanisms
Gears are toothed wheels where the chain or drive belt is dispensed with,
and is replaced by the teeth on the gear wheels meshing together to
transmit motion and force. As with pulleys and sprockets, increases or
decreases in rotary transmission speed can be achieved by meshing
gear wheels of different diameter with corresponding numbers of teeth.
Pawl and Ratchet Mechanism
This type of mechanism is used in old-fashioned football rattles. It
generates a lovely clattering, rattling sound when rotated, which may be
ideal for some toy ideas. The only drawback is that the pawl can only
rotate in one direction. The ratchet is really a gear wheel with its teeth
raked backwards.
Pawl and ratchet mechanism.
Scotch Yoke Mechanism
The Scotch yoke is a really useful mechanism for toy makers; it is also
known as a slotted link mechanism. It is basically a reciprocating motion
mechanism, converting the linear motion of a slider into rotational motion,
or vice versa. The piston, or other reciprocating part, is directly coupled to
a sliding yoke with a slot that engages a pin on the rotating part. The
Scotch yoke creates a reciprocating or oscillating output from a rotating
handle or wheel, without the need for an additional connecting rod as a
crank slider mechanism needs.
Example of the scotch yoke mechanism.
Useful Mechanisms for Toy Makers
Kinetic mechanical toys rely on a fairly basic range of mechanisms and
methods of generating motion or movement, which can be modified by
the toy maker. The mechanical principles described earlier can be
modified and adapted to suit lots of exciting toy-making possibilities. For
the purposes of this book, the most versatile, useful and successful are
described here.
The Synchronized Offset Wheel and Axle
Both wheels behave like an eccentric cam rotating eccentrically around
an axle. This method will generate a small lift and fall effect. The frog
toy’s rear axle uses an offset wheel to cause the rear of the frog to bob
up and down slightly, creating a more frog-like jumping effect. The
wheels have to be synchronized to rise and fall at the same points.
The synchronized offset wheel and axle: the frog toy’s rear axle causes a slight lift and fall.
The Opposed Offset Wheel and Axle
The opposed offset wheel and axle is similar to the synchronized offset
wheel, but the wheels are not synchronized to rise and fall together,
creating a waddling effect. This is achieved by offsetting the axle at the
highest and lowest points respectively on each wheel.
The duck toy uses the opposed offset wheel and axle effect to create the waddling action.
The Offset Drive Axle
The offset drive axle is similar to a Scotch yoke effect, and will convert a
rotary to a reciprocating or oscillating motion to cause a component to
rise and fall or move backwards and forwards with a slight oscillating
motion. The wheels fit on a centred axle and pivot within the interior of
your toy. An extra axle/pivot is used to drive a component backwards and
forwards or up and down.
The offset drive axle can be used to make an output oscillate or reciprocate.
The Inside Wheel Pegs
An inside wheel peg is a small wooden peg in the inside of the drive
wheel that flips a component up and down. Gravity returns the
component to its original position until the second peg on the other wheel
repeats the process. A lovely oscillating head action can be achieved by
synchronizing the inside pegs to create a continuous rise and fall action.
By synchronizing the location of the pegs, it is possible to get two ‘flips’
for every wheel and axle rotation. This is possibly the simplest, most
satisfying and effective method of generating motion in a kinetic toy. The
mechanism is almost hidden and looks amazing. You will need to add
spacer components to your inside wheel and peg mechanism to prevent
the pegs jamming and becoming trapped against the body of the toy.
The dog and crocodile toys in this book use the inside wheel peg technique to flip the head
up and down. The head shape is basically a bell crank.
Example of how an outside wheel peg or pivot can be used to generate a walking action.
Outside Wheel Pegs and Pivot
The illusion of walking or running can be achieved by pivoting a
component away from the wheel’s geometric centre to create a rotary to
an oscillating or reciprocating motion. The dog, frog, crocodile and
dinosaur use this technique to generate a walking action. You must make
sure that the component is able to make a full revolution when attached
to the drive wheel without striking the ground. Wooden pegs located on
the outside of the wheels can be used to flip a component up and down,
using gravity to cause the component to return to its original position for
the cycle to begin again. Alternatively the component, such as an arm or
leg, can be screwed or pegged to the exterior of the wheel to make a
continuous rotary and oscillating action.
The Cam and Follower Mechanism
As mentioned previously, the cam mechanism can be used to turn a
small rotary motion into a reciprocating or oscillating output. For the
purposes of this book, the eccentric cam has been used. The follower is
simply the vertically mounted component that sits in contact with the
surface of the eccentric cam wheel. It reciprocates as the cam wheel
rotates. Gravity causes the follower to return to its original position,
though compression springs can also be used to maintain a smooth
motion. It is vital that the follower is held carefully in place, and able to
travel through its reciprocating cycle easily without jamming. A follower
can also be mounted at a right-angle to the cam wheel and pivoted at
one end, only to generate an oscillating output motion. Again, gravity will
cause the follower to remain in contact with the cam wheel.
Examples of cam and follower mechanisms. The follower can be vertical, or mounted at a
right-angle to the cam and axle. Two output actions can be generated by mounting two or
more eccentric cams to one shaft.
Wheels in Contact or Engaged Wheels
When one wheel is placed in contact with another, the rotary motion can
be transferred through ninety degrees, a bit like gear wheels but without
the meshed teeth. It is also useful to use this method with two eccentric
cams to cause a vertical output to oscillate at a right angle to the drive
wheel. The engaged wheel technique needs sufficient surface traction
between the wheels to work successfully.
The wheel in contact or engaged wheel transfers motion through ninety degrees and also
changes the direction of the output motion.
Putting It All Together
The projects in this book use at least two types of the mechanical
principles explained in this chapter. The real creativity and fun begins
when you start to mix and match different mechanisms to make a more
complex mechanical toy system. A good way to test and model a
mechanical action is to use stiff card and brass paper fasteners.
Modelling mechanisms and designing toys will be dealt with in a later
chapter.
CHAPTER FOUR
TIPS AND TECHNIQUES
The tips and techniques described in the following section will help you
produce the projects in this book more efficiently, happily and easily.
Using Templates and Stencils
Templates and stencils are used to transfer the contours of components
on to the timber blanks. This book contains templates for the production
of most parts for each of the five practical projects described. You can
trace, photocopy and resize the templates to suit the size you want.
Remember that all components must shrink and stretch to the same ratio.
It is recommended that you photocopy the templates, cut them out and
paste them on to the timber blanks with a glue stick. Avoid using PVA or
watery adhesives as these will wrinkle the paper and are very difficult to
remove. You could also mount each template on to card and use it as a
template to trace around.
Glue-stick templates on to the timber to form the components. You can also make template
profiles by gluing the paper profiles to thick card. Thinner components will require careful
alignment of the grain direction to avoid weakness caused by being ‘short across the
grain’.
Locating and Drilling Holes Accurately
Use a centre punch to locate each hole for drilling, and ideally use a
wood drill bit (a twist drill with a spike on the end to locate the hole more
accurately) for drilling. Forstner bits are also ideal for larger diameter, flatbottomed holes. These are used to drill out the holes to hold the mounts
for arms and legs on dinosaur and crocodile bodies.
The location and diameter for every hole that needs to be drilled is shown on the templates
for each project. A wood drill bit is used to locate holes more accurately than standard
twist drill bits. A forstner bit is used for drilling larger diameter, flat-bottomed holes.
Drilling the Holes for Handles
The holes for handles for the frog, dinosaur and robot toy are shown as a
dashed line on the side profile template. The dashed line represents the
centre of the hole’s location. Use a try-square to mount the workpiece
vertically to get the correct angle.
Mount the workpiece in a machine vice with the dashed line representing the hole location
for the handle mounted vertically. Check for true vertical using a try-square.
When gluing, don’t attempt to clamp too early as this only causes the
newly lubricated timber surfaces to slip and slide. Apply an even layer of
glue, and ‘rub’ the join to expel surplus glue and trapped air. Leave the
glue to set for a few minutes and then clamp the components. Wipe away
surplus glue as this will prevent the absorption of any subsequent stains
and colour, leaving nasty white patches.
The drum sander and rotary cutting tools are possibly the most
versatile and liberating power tools. Use them extensively if possible to
sculpt and shape components for the toys in this book. Their advantage
is their speed, also a shaping process that requires no blows from
carving mallets and chisels, and for the most part, you can hold the
workpiece in your hands as you work on it. Rasps, chisels and heavyduty carving will subject small workpieces to stresses and trauma that
risk breaking them before they get anywhere near the inevitable battering
delivered by an exuberant child.
Use the following drum sander diameters to match the concave area
that needs sanding: 13mm, 19mm, 25mm, 38mm and 50mm. The choice
of diameter is dictated by the curvature and radius of the area to be
sanded. Drum sanders fit in a pillar drill where even small wattage motors
offer the torque needed to remove the required material easily. Drum
sanders used with rotary cutting tools are the next choice for sculpting
and shaping material. They are available in diameters of 12mm, 10mm
and 6mm. In addition, the manufacturers of rotary cutting and shaping
tools offer a big range of rasps and cutting tools.
There is another option, but not for the faint-hearted: tool companies
sell a flexible drive shaft to be fitted in the chuck of a pillar drill. The
business end of a flexible drive shaft looks like a conventional rotary
cutting tool, but be warned, they provide a lot of torque and the risk of
nearly breaking your wrist or getting your sweater caught in it. After
ending up with my arm in a sling and the front of my sweater missing, I
decided that flexible drive shafts were bad news. Finally, remember that
without due care and attention the 80-grit abrasive paper on drum
sanders will skin your knuckles and fingers.
Constructing a Hollow Form
The dinosaur and dog toy need an internal cavity to locate the levers and
eccentric cam needed to generate the required movement. This toy
project requires the assembly of three timber blanks to produce an
interior cavity that will accommodate the eccentric cam and head lever. It
is really important to locate the interior spacer components very
accurately. To accomplish this, paste the appropriate template to the
inside face of one of the exterior timber blanks. Use a bradawl or
compass point to make a series of pin pricks to highlight the location of
the perimeter and the location of the interior components. You should
also drill all hole locations on one exterior blank only before glass
papering away all the paper template.
Use a bradawl or compass point to make a series of pin pricks to highlight the perimeter
and location of the interior spacer blocks.
The impression left by the bradawl or compass point can now be
connected with a pencil to guide the accurate location of the interior
spacer blocks needed to complete a hollow bodyshell. Before gluing on
the second half of the body side, test that the levers and pivot point work
correctly, and modify these with a chisel if necessary.
Glue into place the spacer blocks that create the cavity/housing for the lever and eccentric
cam. Rub away the paper templates, and place the axles and dowels in ‘dry’ to test the
mechanism.
Glue the second half of the bodyshell into place. Once dry, complete all axle holes and
pivot points by running the appropriate sized drill bits through the previously drilled holes.
This is essential to avoid the holes not lining up. The leg and arm mounts for the dinosaur
and crocodile toy need to be enlarged with a forstner bit after an initial pilot has been
made. A timber insert is glued in to provide a true, even surface upon which to mount the
legs or arms.
Fitting Arm and Leg Levers to a Curved Surface
Some holes, such as the leg and arm mounts for the dinosaur and
crocodile toy, need to be enlarged with a Forstner bit after an initial pilot
hole has been made. The cavity is then plugged with an 18mm or 25mm
dowel. This is to allow for a level, parallel, square surface upon which to
mount arms and legs after the body shape of the toy has been sculpted
and rounded over. The arms or legs must be completely parallel with the
exterior of the wheel surface in order to run smoothly. This technique
allows for a more sculpted and less ‘blocky’ toy form, while allowing the
legs and wheels mechanism to move easily and evenly. The holes that
require expansion and plugging must be drilled before the body shape is
sculpted and rounded over! The locations and dimensions for the plugs
needed will be given in the chapters dealing with each relevant project.
Making Wheels
Wheels can be produced in several ways or purchased from a craft
supplier. If you have access to a sanding machine, you can make a
simple jig to allow the production of different diameter wheels to a fairly
high dimensional accuracy. The wheel blanks are located on the sanding
jig and rotated by hand against the rotating sanding disc. The diameter of
the timber blank is reduced incrementally until the required final diameter
is achieved. Care needs to be taken to avoid sanding knuckles and finger
tips.
A simple sanding jig can be produced that can be clamped to the bed of the orbital sander
or similar. The proximity of the arm to the sanding disc determines the final diameter of the
wheels produced. Each blank is rotated against the disc individually and reduced in
diameter incrementally. The timber blank for the wheel fits over, and rotates on a 9mm
dowel located at the end of the arm.
CHAPTER FIVE
PAINTS AND FINISHES
There is a bewildering range of paints and finishes available for a wide
variety of materials and purposes. All paints and finishes perform two
essential tasks: firstly, to seal and protect the surface of the material from
atmospheric corrosion and damage; also timber is prone to shrinking and
stretching and must be sealed to prevent distortion and the penetration of
dirt, oil and grease. Their second task is to decorate and embellish.
Colour is an aesthetic component especially important to toys and
playthings. Colour should be thought of as a unique component in itself,
to be used carefully. All paints and finishes have their own
characteristics, which can look amazing if used correctly.
Timber toys need careful surface preparation before the application of
any finish. After rough shaping, cross filing and draw filing, use an 80-grit
glass paper followed by 120-grit, 240-grit and finally a 1,200-grit paper for
a super-smooth surface. Be careful to glass paper in the direction of the
grain. A useful technique is to glue glass paper to a board and rub the
workpiece on it. Be careful to rotate the workpiece and change direction
so that you do not rub it unevenly.
The paints and finishes available are itemized below, with a brief
description of each one. As a toy maker, it is useful to have a good
understanding of paints and finishes as a component. Keep in mind that
timber has its own figuring and patination, which can be used
expressively – it isn’t always necessary or desirable to suppress its
natural appearance.
Types of Paints and Finishes
Emulsion Paint
Emulsion paint is a water-based paint based on an acrylic or vinyl resin
medium. It is available in a matt, eggshell or gloss finish depending upon
the quantity of medium used. It is used for interior timber decorating, and
is available in a wide range of colours. It is water soluble.
Gloss Paint
Gloss paint is an oil-or polyurethane-based paint made for interior and
exterior timberwork. Gloss paints require the careful application of a
timber primer, an undercoat and several top coats to get the full
decorative and protective qualities of a gloss paint. Gloss paints are
soluble in white spirit/turpentine. They are difficult to use on small, toy like
objects without leaving brush marks and paint runs/drips.
Enamel Paints
Enamel paint is another oil-based paint with a high gloss finish. It
provides a very hardwearing, glossy, non-porous surface that makes it
ideal for toy making, children’s furniture and interior decoration. These
paints cover well and apply easily and evenly. They are also available as
spray paints, and can be used on plastics and metals. Use white
spirit/turps as a solvent. Enamels are ideal for toy-and model-making
purposes.
Cellulose Paints and Lacquers
Solvent-based paints are often found in spray cans, and dry a lot faster
than other types of paint. There are non-spray types available, but these
are hard to apply with brushes. These paints include fascinating finishes
such as speckled and hammered. Solvent sprays can be very expensive,
but give very good results on small projects. A cellulose-based solvent is
needed for cleaning up. Good ventilation is compulsory as the vapours
are very toxic and flammable.
Cellulose paint/varnish can be easily thinned for spraying, it dries
quickly, and is hard wearing and durable. It used to be used for car
bodies, but has largely been replaced by less dangerous acrylics and
enamels. Cellulose thinners are used as a solvent. ‘Hammerite’ is a good
example of a cellulose paint.
Cellulose paints and lacquers can be used on plastics and metals.
Cellulose lacquer is a hardwearing, clear finish that can be sprayed
rapidly to seal the surface of your toys. Be careful you don’t spray it over
other cellulose paints as it will cause the underlying layer to wrinkle and
lift.
Polyurethane-Based Varnishes and Paints
Because of its polyurethane content, polyurethane paint is similar to
liquid plastic when wet. Use this type of paint/varnish to protect interior
and exterior timberwork from scratches and dents. Polyurethane
paint/varnish comes in three types: water-based, oil-based and
oilmodified water-based. It has a hardwearing, durable but slightly plasticlooking surface.
Shellac Sealer/Button Polish
This sealer is used as part of the French polishing technique. It provides
an excellent method of sealing timber before polishing with wax. It is also
ideal to seal in dyed colour prior to waxing or varnishing. It is not very
durable and can be easily damaged by water. Methylated spirits must be
used as a solvent. Take care as both shellac sealer and meths are highly
flammable.
Shellac sealer or sanding sealer is an excellent method of sealing a
timber surface to prevent moisture swelling the wood fibres near the
surface and causing the grain to raise. When dry, these fibres stick up
and dry, leaving a horrible prickly surface. Timber toy components can be
sealed with shellac after dyeing or colouring, and then given additional
coats of polyurethane varnish or cellulose lacquer to make a more
durable, hardwearing surface.
Wax and Oil Finishes
Wax and oil finishes can be applied over a dyed and shellac-sealed
surface. They are ideal for polishing turned items and small decorative
items. Wax is a good water repellent but leaves white stains when
exposed to too much moisture, especially if used over shellac. Waxes
can be natural or silicon based. Wax finishes are high maintenance and
not very durable. Oil finishes are good for external timberwork, especially
tropical hardwoods.
Water-Based Wood Dyes
Colour can be applied to timber by using wood dyes; these are easily
available in DIY stores. Many wood dyes are water based, which causes
the grain to raise, giving the timber an unpleasant fuzzy texture when dry.
Spirit-based dyes avoid this problem, and can then be easily sealed with
a suitable varnish. A water-based wood dye can easily be made from
thinned acrylic paint or similar.
Spirit-Based Wood Dyes
Spirit-based wood dyes can be made by combining oil paints or edible
food dyes and surgical spirit. A wide range of colours and tones can be
achieved with experimentation. Spirit-based wood dyes do not raise the
grain, and like water-based dyes are only a decoration without any
protective qualities. The dyed timber needs to be sealed in with a suitable
varnish. When dyeing timber, the rule to remember is that the colour
begins light and can only ever be darkened. Experiment on scrap pieces
of timber to see what is possible. Finally, wood dyeing is only generally
effective on timbers that are already pale, such as beech or redwood.
Surface Treatments for External Timberwork
If you plan to produce toys for outside, the timber needs to be protected
from moisture penetration, insect attack and fungal infection. Tanalizing
is a treatment where the timber fibres are placed within a vacuum and
then injected with an oil-based insecticide and water repellent. Timber
can also be painted, sprayed or dip-coated using a variety of coloured
preservatives. Some can be very toxic.
CHAPTER SIX
THE FANTASTIC FROG
The frog’s rear wheels and legs generate a slight jumping action and
cause his big glum mouth to open and close as the toy is pushed along.
He uses a simple, bell crank-type lever for a head, and class three levers
for rear legs that pivot and rotate on the rear wheels. Both rear wheels
are synchronized and mounted eccentrically on the rear axle. Every
rotation of the rear wheels makes a slight bobbing action.
He is made from redwood, but you can choose whatever timber you
like. Prepare all parts and use a spirit-based stain to make the green
colour. The surface pattern decoration was made by spraying paint
through a stencil made from MDF offcuts. Finally, polyurethane varnish
was used to seal the surface of all components before assembly.
The completed frog toy.
To make the frog toy, prepare the following materials:
CUTTING LIST FOR THE FROG TOY
Part
L×W×T
Quantity
Material
Body blank
A
150 × 130 × 20mm
2
Redwood
Head centre
B
60 × 50 × 44mm
1
Redwood
Head sides
C
90 × 80 × 10mm
2
Redwood
Wheels
55 × 55 × 29mm
4
Redwood
Rear axle
70 × 9mm dowel
1
9mm dowel
Front axle
70 × 9mm dowel
1
9mm dowel
Front axle
70 × 9mm dowel
1
9mm dowel
Upper legs (long)
D
130 × 50 × 10mm
2
Redwood
Upper legs (short)
E
110 × 50 × 10mm
2
Redwood
Lower legs
F
130 × 50 × 10mm
2
Redwood
Handle
400 × 18mm diameter dowel
1
18mm dowel
Handle hand grip
95 × 25mm diameter dowel
1
25mm dowel
Eyes
10mm diameter wooden beads approx.
2
Hardwood beads
FIXINGS NEEDED TO PRODUCE THE FROG TOY
Part
Fastening
Quantity
Jaw pivot
10-gauge × 1in round-head, black Japanned screw
2
Upper leg pivots
(fixing the leg to the
body)
10-gauge × 1½in round-head, black Japanned screw
2
‘Elbow’ pivot
M4 lock nut and 40mm pan-head screw with two M4 washers.
(Screw/bolt head faces inwards to avoid jamming on the
frog’s jaw)
2
Wheel pivot
10-gauge × 1in round-head, black Japanned screw
2
Templates for the Frog Toy
The templates for the frog toy need to be expanded to fill an A3 size
piece of paper. Enlarge the templates on a photocopier until the diameter
of the wheel templates measures exactly 50mm.
Templates for the frog toy components need to be enlarged on to an A3 size page in order
to get the correct scale and ratio of components. All locations and diameters for the holes
to be drilled are shown in millimetres.
Constructing the Frog Toy
Step 1: Assembling the body
1. Photocopy and cut out the templates for the frog body (2 × part A).
Shape and glue on to a 20mm thick piece of timber.
2. Use the first piece to trace around and make a second body shape.
Glue the two frog body shapes together to form a 40mm thick body
blank. Make sure the pasted template is clearly visible, and centre
punch the location for all holes. Drill out the holes for the axles, head
and leg pivots.
Step 2: Drilling the 12mm hole for a handle
Drill out a 12mm hole to a depth of 25mm in the back of the frog to
receive a handle. Use the dashed line shown on the template to guide
the position and angle of the timber body blank in a machine vice. Use a
try-square to check for vertical. The timber body blank and machine vice
must be completely parallel with the edges of the pillar drill bed or you will
inadvertently drill a compound angle, which is useful for chair making but
not frog push/pull handles.
The frog toy body blank must be mounted into a machine vice as shown to drill the hole for
the handle at the correct angle.
Step 3: Assembling the components for the frog’s head
1. Paste the head centre (part B) on to a block of 44mm thick timber and
carefully cut it out.
2. Make two head sides (part C) from 10mm thick timber, taking care to
make sure the grain is located top to bottom to avoid splitting.
Cut out, clean up and assemble the components for the frog’s head, taking care to wipe
away any surplus adhesive.
3. Clean up the concave areas of the head components with files, glass
paper and drum sanders, and assemble them using PVA. Allow the
glue to set slightly before clamping in a vice. Wipe away any surplus
adhesive.
Step 4: Drilling the holes for the head
1. Centre punch the location of all holes needed.
2. Drill out the 5.5mm holes for the frog’s head pivot point. (Make sure to
pack the cavity to prevent the wood splitting and cracking.) Drill all the
way through from one side only.
3. Drill the 5mm location on each side of the head for the eyes, to a
depth of 10mm. Countersink the location of each eye to receive a
wooden bead later.
When you drill out the head pivot, make sure to pack the cavity between the head sides
with scrap timber to prevent splitting.
Step 5: Fitting and testing the head and the frog’s body
1. Fit the head to the body. Pin it temporarily with a wood screw. Test
that the head moves freely and easily, and adjust any tight spots with
files and glass paper if necessary.
2. Use files, glass paper and drum sanders to clean up the edges and
surfaces of your frog’s head and body.
3. Remove all traces of the paper template once drilling and test fitting
are complete.
Finally, radius the edges of the frog’s body. You can do this with an
electric router if available, otherwise use a rasp, files and glass paper.
Temporarily assemble the frog’s head and body and radius the edges, taking care they are
not excessively round over the axle locations.
Step 6: Making the wheels and axles
1. Mark out four wheel blanks measuring 54 × 54 × 20mm.
2. Find the centre of each wheel blank by connecting the diagonals, and
draw a 25mm radius circle on each wheel blank to form a circle of
50mm diameter. Repeat for both sides of the wheel blank.
3. Centre punch both front wheel centres before drilling. Drill both front
wheel centres to a depth of 15mm using a 9mm diameter drill bit.
4. The rear wheels have the axle centre offset from the circumference
by 20mm to create a frog-like hopping action. To achieve this, mark
the axle centre 20mm from the circumference, and drill out a 9mm
axle hole on each wheel, as described for the front wheels.
5. Flip the rear wheels over and drill a 2.5mm pilot hole for the legs to
pivot on the rear wheel exteriors. The 2.5mm pilot hole must be
directly opposite on the circumference to the location of the rear
wheel axle location to make a convincing lift and fall action.
6. Remove the waste from the wheel blanks until they are completely
circular. Use glass paper to radius the circumference edges of each
wheel. Glass paper to finish, and dry assemble both axle assemblies
to test for accuracy. Both rear wheel axle locations must be
completely parallel with each other to make the lift and fall action,
without any oscillating side to side, which would spoil the motion.
7. To find more helpful information on wheel making, refer to Chapter 4
‘Tips and Techniques’.
Cut out and assemble the wheels and axles. Remember that the rear wheels turn
eccentrically to generate the rise and fall motion at the back of the frog’s body.
Step 7: Assembling the wheels and axles, and cutting out
the leg components
1. Make two axles measuring 75mm. Make a ‘dry fit’ assembly of the
wheels, axles, head and body to test for accuracy.
2. Paste the templates for the leg components (parts D, E, and F). Cut
out the leg components using a scroll saw, coping saw or a bandsaw.
3. Assemble the components for the upper legs (parts D and E). Make
sure the spur projecting from part D is eventually flush with the frog’s
body. Put part D over part E to form the upper leg. Clean up and drill
out all the holes for the leg components.
Cut out all the leg components and drill out all the holes to the required diameter.
Carefully assemble and locate the upper leg so that the spur projecting from its edge will
strike the frog’s jaw, causing it to lift and fall.
Step 8: Sculpting and shaping the frog’s head using drum
sanders and rotary tools
1. Shape and sculpt the frog’s head using a combination of different
diameter drum sanders and rotary cutting tools. Or, you can simply
radius the edges of the frog’s head without any more complex
shaping.
2. For the purposes of sculpting the head, begin with a 140mm radius,
80-grit drum sander to round over the head front, and then progress
to a 10mm and 6mm 80-grit drum sander attached to a rotary cutting
tool. The sequence for sculpting the frog’s head is shown in the
accompanying illustrations.
3. Before beginning the shaping, countersink the eye cavities to receive
a bead for an eye later.
Finally, round over the underside of the frog’s lower jaw shape to give it
that glum, doublechin effect, and blend in the upper and lower jaw
shaping.
Countersink the eye spacers to a depth of 10mm.
Use a 13mm drum sander to begin the gap between the frog’s bulbous eyes.
Round over the front of the frog’s head using a 140mm drum sander.
Round over the front of the head using a 140mm drum sander.
Use a 13mm drum sander to hollow the area below each eye.
To create the frog’s overbite lips and glum expression, use a 13mm drum sander to hollow
the area above the front of the frog’s head.
Glass paper the head to remove all rough areas, and sculpt the lower jaw area on the frog’s
body to ‘blend in’ the sculpting.
Fit the frog’s head to the body temporarily using a woodscrew and file, then sand, sculpt
and shape both components together to ‘blend them in’.
Step 9: Assembling the legs and joining them to the body
1. Assemble a pair of upper leg assemblies (parts D and E). Attach a
lower leg component (part F) to each upper leg assembly, as shown.
2. Fasten the lower leg to each upper leg assembly using a 40mm
machine screw and M4 nylon lock nut. Take care not to overtighten
the nut.
3. Fasten each leg assembly to the frog body using an 8-gauge × 1½in
round head, black Japanned screw. For the sake of clarity, the
examples shown are unpainted or decorated. (It is much better to
decorate and seal each component before assembly.)
Assemble the lower legs to the upper legs, and fix to each side of the frog’s body. Make
sure the spur that projects from the upper leg assembly is fitted flush to the side of the
frog’s body.
Step 10: Fixing the legs to the wheels
1. ‘Dry fix’ both axles and wheel assemblies into place, and make sure
the rear wheels are synchronized to rise and fall at the same time in
order to create the hopping action.
2. Drill pilot holes on the exterior of the rear wheels to receive the frog’s
lower leg (part F). Both pilot holes are 12mm from the circumference
of each rear wheel and located opposite the rear wheel axle
locations. Make sure the legs are synchronized to drive the head up
and down simultaneously and maximize the lift and fall action.
3. Fasten the lower leg to the rear wheels as they reach their highest
points during rotation. The pilot hole for each leg pivot should be
located from the opposite circumference to the axle location.
Dry fit the wheels and axles into place, and mark out the location for the 2.5mm pilot holes
to receive an 8-gauge × 1in round head, black Japanned screw to make the lower leg pivot
against each wheel.
Step 11: Fitting a handle
1. Add a handle made from 400 × 12mm diameter dowel. The top of the
handle can be fitted with a hand grip made from 95 × 25mm diameter
dowel.
2. Centre punch the hand grip to receive a 12mm hole for fastening it to
the handle.
Glue the handle grip to the handle using PVA. Test the assembled toy for
accuracy and smooth movement. Use wax to lubricate any stiff areas.
Assemble the handle by adding a cross-piece to act as a hand grip, and secure it with pva
and a 10-gauge 1¾in woodscrew.
Step 12: Finishing and decorating
1. The frog toy example has been stained with green vegetable-based
food colouring suspended in a solution of surgical spirit. The process
provides gorgeous hues and tones without obliterating the underlying
wood grain. The method also allows coloration without raising the
wood grain as water-based dyes will.
2. When dry, a pattern has been sprayed using enamel paint through a
card stencil made from laser cutter offcuts. Make your own stencil by
cutting shapes into carton board with a super-sharp scalpel. Apply the
stain solution quite liberally with a brush, using a rag to wipe away
any surplus solution. Each coat of stain will darken the hue according
to the ratio of pigment to spirit.
3. It would be wise to experiment on scrap timber first – and remember
that you can never lighten the hue. Paint the components as if you
were working on a watercolour painting, where the golden rule is,
always work from light tones or hues to dark. It will not work in
reverse!
When the colouring and varnishing of individual components is complete,
assemble the frog toy for the final time.
Applying the Finish and Decoration
1. Sand all components, beginning with an 80-grit glass paper, followed
by 120-grit, 240-grit and finally a 1,200-grit.
2. Apply two or three coats of polyurethane varnish or cellulose lacquer.
Rub down between the first two coats of varnish with 240-grit and the
last, third coat with 1,200-grit.
3. When the third and final coat of varnish has dried completely, a layer
of silicone or beeswax can be added to lubricate and reduce surface
friction.
4. Paint the eyes yellow and add a vertical pupil to give the frog its
froggy stare. Glue the eyes into place using a two-part epoxy
adhesive.
The frog toy has been stained using a combination of edible food dye and surgical alcohol.
Once stained and dried, a pattern was added by spraying enamel paint through a card
stencil. Finally, the surface has been sealed with three coats of polyurethane varnish.
CHAPTER SEVEN
THE HUNGRY HOUND
The hound dog toy snoops, sniffs and yaps as he is pushed or pulled
along. His legs generate a walking action, and the tail flips up and down,
driven by an eccentric cam and follower hidden between the rear wheels.
The head is basically a bell-type crank similar to the frog, but is flipped up
and down by two inside wheel pegs located on the interior of each front
wheel. He can be pushed with a handle just like the frog toy. The
components for the hungry hound have been individually finished and
decorated with enamel spray paint before assembly.
To make the dog toy, prepare the following materials:
The completed dog toy.
CUTTING LIST FOR THE DOG TOY
Part
Ref: L × W × T
Quantity Material
Body blank
A
250 × 120 × 20mm
2
Redwood
Body blank centre
B
250 × 120 × 20mm
1
Redwood
Head centre
C
100 × 40 × 50mm
1
Redwood
Head sides
D
120 × 65 × 10mm
2
Redwood
Eccentric cam
E
35 × 35 × 20mm
1
Redwood
55 × 55 × 20mm
4
Redwood
Wheel blanks
Wheel blanks
55 × 55 × 20mm
4
Redwood
Front wheel axle
spacers
18 × 14mm dowel
2
Dowel
Rear wheel axle spacers
18 × 5mm dowel
2
Dowel
Inside wheel pegs
20 × 9mm dowel
2
9mm dowel
Cam follower
6mm diameter dowel × 25mm
1
6mm dowel
Rear axle
9mm diameter dowel × 85mm
1
9mm dowel
Front axle
9mm diameter dowel × 95mm
1
9mm dowel
Pivot for wagging tail
6mm diameter dowel × 60mm
1
6mm dowel
Upper front legs
F
80 × 50 × 20mm
2
Redwood
Lower front legs
G
100 × 50 × 10mm
2
Redwood
Upper back legs
H
100 × 50 × 10mm
2
Redwood
Lower back legs
I
100 × 50 × 10mm
2
Redwood
Tail profile
J
150 × 55 × 12mm
1
Birch
plywood
Tail width extension
K
70 × 25 × 9mm
2
Birch
plywood
Handle
400 × 18mm diameter dowel
1
12mm dowel
Handle hand grip
95 × 25mm diameter dowel
1
25mm dowel
Front leg spacers
18 × 14mm dowel
2
18mm dowel
Rear leg spacers
18 × 5mm dowel
2
18mm dowel
Eyes
6mm wooden beads
2
Nose
18mm or equivalent wooden
bead
1
FIXINGS NEEDED TO PRODUCE THE DOG TOY
Part
Fastening
Qty
Jaw pivot
10-gauge × 1in round-head, black Japanned screw with M4
washer
2
Upper leg pivots (fixing
the leg to the body – front
legs)
8-gauge × 1¾in round-head screw
2
Upper leg pivots (fixing
the leg to the body – back
legs)
8-gauge × 1in round-head screw
2
‘Elbow’ pivot
M4 lock nut and 25mm pan-head screw with two M4
2
‘Elbow’ pivot
M4 lock nut and 25mm pan-head screw with two M4
washers. Screw/bolt head faces inwards to avoid jamming on
the dog’s jaw
2
Wheel pivot
8-gauge × ¾in round-head, black Japanned screw with M4
washer
2
Screw for fastening cam
wheel to axle
6-gauge × ¾in, countersunk-head woodscrew. Screw 1
1
Templates for the dog toy components. Enlarge the templates on a photocopier until the
diameter of the wheel templates measures exactly 50mm. All locations and diameters for
the holes to be drilled are shown in millimetres.
Templates for the Dog Toy
The templates for the dog toy need to be enlarged to A3 paper size.
Enlarge the templates on a photocopier until the diameter of the wheel
templates measures exactly 50mm.
Constructing the Dog Toy
Step 1: Forming the body components
1. Cut out the three components that form the dog’s body. Make sure
the template for part A is pasted on the inside surface of one of the
body sides. You will need to make two part As. Centre punch and drill
out all the holes to the required diameter on one outside panel for the
dog’s body.
2. Prepare the location for fitting the middle component to create the
housing for the cam and follower (located above the rear axle and
wheels). The technique for locating the centre/spacer component
accurately is described in Chapter 4, in the section ‘Constructing a
Hollow Form’.
Prepare the components for the dog’s body form. The completed form consists of three
parts. The inside component creates the cam and follower housing to make the tail
oscillate/wag.
Step 2: Forming the body spacer component
The centre component for the body (part B) has a blank area that forms
the housing for the eccentric cam and follower to drive the tail. It will need
a 6.5mm hole drilled carefully and accurately to house the cam follower.
Mount the body centre component into a machine/ hand vice as shown,
and check to get a true vertical using a try-square before drilling a hole
that passes through all the paper template area.
The dashed line on component B (the body centre) is used to guide the 6.5mm drill through
the area above the eccentric cam to allow a 6mm dowel follower to move easily and drive
the tail up and down. Drill it out before you cut the exterior profile of the component.
Step 3: Assembling the body blank
1. Use a drum sander to clean up the concave areas of the body
components, especially around the cam and follower housing, as
these will be inaccessible once the body has been glued together.
2. Sand the template from part A before gluing and clamping the three
body components together. When the glue has dried, drill all the
holes for the axles and pivot points all the way through by guiding the
drill bit through the holes previously drilled through part A.
3. Drill a 12mm hole to a depth of 30mm for the handle, using the
dashed line on the template as a guide. Mount the glued-up body
blank in the hand/machine vice with the dashed line projecting
upwards. Use a try-square to check for a true vertical, and carefully
centre punch the hole location.
The dog’s body is reduced in width to make it look less heavy and less ‘blocky’. The
haunches are left wider to emphasize the stooped, snuffling action.
Glue and complete the drilling for the body blank by guiding the appropriate sized drill bits
through the previously drilled holes on part A.
Step 4: Roughing out the body blank
Use a marking gauge and try-square to mark out the body blank to the
dimensions shown. Use a bandsaw to cut away the waste areas, taking
care to keep the body blank squarely on the bed of the bandsaw. It might
be useful to make a series of straight cuts or kerfs at a right angle to the
scribed lines to make removal of waste easier, as the bandsaw doesn’t
need to pass through the tight curve at the end of the dog’s haunches.
Step 5: Shaping and finishing the body blank
Round over, sculpt and shape the dog’s body using a variety of drum
sander diameters fitted to the pillar drill. Use the following diameters to
match the concave area that needs sanding: 13mm, 19mm, 25mm,
38mm, 50mm and 140mm. The choice of diameter is dictated by the
curvature and radius of the area to be sanded. For the bulk of waste
removal, the 140mm diameter sander with an 80-grit paper will suffice.
Note: It is very important not to round over the points where the dog’s
legs and head will fit/pivot, as this will make it difficult for them to move
properly and will leave nasty gaps.
The finished form for the dog’s body is becoming recognizable, with the housing for the
tail and eccentric cam becoming more defined. The area for housing the tail is clearly
visible.
Glue the components for the head as shown. Line up the exterior contours of the front of
the dog’s head to locate the centre piece accurately.
Step 6: Assembling the components for the head
Cut out two parts D (head sides) and one part C (head middle). Glue up
the components to form the head blank. Leave the glue to set a little
before clamping to avoid slipping.
Step 7: Drilling out the pivot point for the head and locating
the position for the eyes and nose
1. Once dry, pack the cavity between the head halves with a piece of
scrap timber before drilling a hole all the way through for the head
pivot using a 5.5mm drill bit. The location for the head pivot point is
shown on the template.
2. The eyes and nose can be located by using a try-square and marking
gauge. The important thing is that the eyes are equi-distant from the
edges, and that the nose is centred. With a 5.5mm drill bit, drill to a
depth of 10mm for both eyes and nose.
3. Use a countersink bit to expand the holes for the eyes and nose to
receive a wooden bead later. It is essential to complete all drilling and
countersinking before sculpting and shaping the dog’s head.
Drill the head pivot all the way through using a 5.5mm drill bit. The location for the hole is
shown on the paper template. Pack the cavity with scrap timber to prevent splitting.
Mark out the location for the dog’s eyes and nose as shown. Drill the 5.5mm holes to a
depth of 10mm.
Step 8: Shaping the dog’s head
1. Use drum sanders to shape and sculpt the dog’s head. Begin by
tapering the head from the back to the front to give the appearance of
a canine snout. Round over the sides and edges of the head. Do not
round over the underside of the dog’s jaw!
2. Eventually, a 10mm wooden bead can be used to form a nose and
two 6mm beads for eyes. Glue the beads into place after staining,
painting and sealing are complete.
3. The final addition to complete the dog’s head are ears made from
leather or vinyl screwed to the sides of the head. After shaping,
temporarily fix the head to the dog’s body, and glass paper them
together.
A completed head form gives you a good guide for shaping and sculpting the dog’s head.
The snout projects upwards and the sides are slightly concave.Let the drum sander
diameter determine the required curvature.
Step 9: Making the wagging tail
1. Cut out part J from 12mm birch plywood. Drill a 7mm hole for the tail
pivot point. Cut two K components, which form the sides of the top of
the dog’s tail. Glue both K components on to the upper surfaces of
part J, and leave to dry.
2. Use a 140mm drum sander to round over and taper the tail assembly
to the form shown in the photograph.
3. Glue a packing piece of 18mm dowel or similar on each side of the
dog’s tail, and roughly half way down it, to prevent it rocking
excessively from side to side.
The tail is driven by an eccentric cam and follower concealed between the back axle and
the rear end of the dog.
When dry, sculpt the dog’s tail with a 140mm drum sander, and then glass paper the
completed form. Glue a packing piece on each side of the dog’s tail to prevent it jamming
against the sides.
Step 10: Fitting the wagging tail
1. Peg the tail assembly into the 6mm pivot point located at the back of
the dog’s body. Test it for free movement, and adjust as necessary.
Fit the 6mm diameter × 25mm dowel cam follower into the cavity
located above the cam housing.
2. Dry fit the 85 × 9mm rear axle, and thread the eccentric cam over
until it fits centrally. You must make sure to trap the cam follower
above it.
3. Dismantle the tail assembly ready for finishing and painting.
The cam follower housing is located above the cam housing between the rear axle.
Temporarily screw the eccentric cam to the axle using a 6-gauge × ¾in, countersunk-head
woodscrew. Make sure the axle protrudes the same distance from each side of the dog’s
body. Fit and test the rear axle for smooth movement and to make sure the cam will make
the tail oscillate easily.
Step 11: Making the wheels
1. Find the centre of each wheel blank by connecting the diagonals, and
draw a 25mm radius circle on each wheel blank to form a circle of
50mm diameter. Repeat for both sides of the wheel blank. Centre
punch both front wheel centres before drilling.
2. Drill both front wheel centres to a depth of 15mm using a 9mm
diameter drill bit. Next drill a 9mm hole 10mm in from the
circumference of both front wheels, and drill to a depth of 10mm to
receive the inside wheel pegs used to flip the head up and down.
3. Turn the front wheels over and drill a 2.5mm pilot hole on the
opposite side of the circumference to the inside wheel peg location.
The 2.5mm pilot hole must be directly opposite to the location of the
inside peg location in order to create the walking action. Each pair of
front-leg assemblies will rotate/oscillate against the front of each pair
of wheels once for every rotation of the front axle.
4. Repeat this process to produce the pilot holes for the location of the
rear wheels. A ‘one up and one down’ configuration of the leg
locations is essential to create the walking action.
5. Remove the waste from the wheel blanks until they are completely
circular. Use glass paper to radius the circumference of each wheel.
Glass paper to finish, and dry assemble both axle assemblies to test
for accuracy. To find more helpful information on wheel making, refer
to Chapter 4, ‘Useful Tips and Techniques’.
The front and rear wheel assembly, showing the 25mm-diameter axle-spacer blocks used
on the front axle to prevent the inside pegs from jamming.
Step 12: Making the front and rear axles
1. Cut a 95mm length of 9mm diameter dowel for the front axle. Cut an
85mm length of 9mm dowel for the rear axle. All wheels are 50mm in
diameter. Produce them in the same way as the wheels for the frog
toy. The holes for both front and rear axles must be set to a depth of
15mm.
2. The front wheels have a 9mm inside peg set on the interior of each
front wheel. Locate the position for the peg for each wheel by
measuring 10mm from the circumference to the centre of the hole
location for the peg. Remember, the front wheels will need to be
synchronized eventually to cause a lift and fall for every rotation of the
axle.
3. The rear axle is 85mm in length and made from 9mm diameter dowel.
The rear axle requires two spacer blocks placed between the top of
the upper rear legs and the dog’s body to project the leg assembly
away from striking the dog’s side and jamming. The spacer also
causes the lower part of the leg to line up parallel with the wheel
exterior. Each spacer is cut from a 25mm diameter dowel to a
width/length of 5mm. Drill a 5.5mm hole through the centre of each
rear leg spacer. Do not glue the spacers, but let them move freely to
help reduce friction.
4. The front axle needs two spacer blocks to prevent the inside pegs
that cause the dog’s head to lift and fall, jamming against the edge of
the head or body. Take a piece of 25mm diameter dowel and bore out
the centre with a 10mm drill bit. Use a bandsaw to cut two 12mm
lengths and slide them over the axle.
5. Cut two 9mm diameter dowels to a length of 20mm, and press them
into the holes on the interior of the front wheels to form the pegs that
will flip the dog’s head up and down.
6. The exterior of all wheels needs a 2.5mm pilot hole for the leg pivot
points. Drill the 3mm pilot hole 12mm from the circumference of each
wheel. Remember that each pair of axles needs a ‘one up, one down’
configuration to generate the walking action of the dog’s legs.
Step 13: Assembling and fitting the legs to the body and
wheels
1. Assemble two pairs of front legs (parts F and G) using an M4 lock nut
and 40mm pan-head screw with two M4 washers. The screw/bolt
head faces inwards to avoid the screw jamming on the dog’s jaw.
2. Assemble two pairs of rear leg (parts H and I) rear wheels. Again, use
an M4 lock nut and 40mm pan-head screw with two M4 washers. The
screw/bolt head faces inwards to avoid the screw jamming on the
dog’s body.
3. Both front wheel assemblies have an 18mm diameter × 15mm spacer
between the upper rear leg and the dog’s body. The spacer causes
the lower leg to line up parallel with the wheel exterior. Do not glue
the spacers, let them move freely to help reduce friction.
4. Both rear wheels have an 18mm diameter × 5mm dowel spacer
located between the upper leg and the dog’s body. Again, the spacer
causes the lower leg to line up parallel with the wheel exterior. Don’t
glue the spacers, let them move freely to help reduce friction.
5. A 10-gauge × 1¾in round-head screw passes through the rear of the
front upper leg, through the spacer, and fastens into the dog’s body.
Cut the spacer from 25mm diameter dowel and drill a 5.5mm hole
through the centre to receive the woodscrew. Don’t glue the spacers,
let them move freely to help reduce friction.
6. Use an 8-gauge × ¾in round-head, black Japanned screw with an M4
washer to fasten the lower leg to the exterior of the wheels. Line up
the wheels to create the alternate lift and fall action of each pair of
legs to create the walking action.
7. ‘Dry fit’ the whole dog toy assembly after fitting the head into place
with two 8-gauge × ¾in round-head, black Japanned screws. Test the
whole assembly for ease of movement, and adjust as necessary with
files and glass paper. After testing, dismantle all the components and
prepare for painting and final assembly.
Disassembled view of how the legs fit. Make sure the screw heads face inwards to avoid
the nut and bolt striking the body. Finally, use a hacksaw to cut off the protruding bolt, and
file the ends smooth.
Step 14: Finishing, decorating and assembly
1. As with previous projects, make sure to glass paper and prepare the
components before assembly. Spray them with two coats of grey
primer undercoat, and rub them down with 1,200 grit paper when dry.
2. Spray the underside of the body and head with two coats of a
creamy, off-white enamel or cellulose paint.
3. Spray the top of the head and body with a dark brown colour. Aim to
make a graduated change between the creamy underside colour and
the upper brown colour. Spray the leg components, tail and wheels
with the same brown colour.
4. Make a stencil/mask to spray a patchy pattern on the dog’s body with
either a lighter or a darker colour. Apply two or three coats of paint
spray, and rub down with 240-grit paper between coats. Use a 1,200grit paper before applying the final coat of paint.
5. Spray the tail tip black, and also the wooden bead for the nose. Paint
the eyes white, and add a larger pupil to stop the eye looking too
reptilian.
6. When all the colour has dried thoroughly, add a coat of wax to
surfaces in contact with each other to reduce surface friction. Polish
the wax before assembly.
7. When all the components are complete, assemble them for the final
time using PVA where appropriate. Glue both the 12mm-thick handle
and the hand grip into place using PVA. Paint the eyes and nose, and
glue them into place with a two-part epoxy adhesive.
8. Finally, use two pieces of leather or vinyl screwed to the top of the
head for ears.
CHAPTER EIGHT
THE RETRO ROVING ROBOT TOY
The robot marches, rattles and clatters along, driven by an outside wheel
pivot joined by a connecting rod between each wheel arm. As he strides
mechanically along, his jaw opens and closes, driven by an eccentric
cam and follower which is partially concealed between the axle and his
body. He has a lovely big mechanical overbite, and a cheerful expression
inspired by some of the mechanical toys and robot sciencefiction
characters from the 1950s and 1960s. The plans for this character offer
the opportunity of making a marching or a walking figure; they could also
include a bent wire connecting rod between the arms and wheels, making
him look less blocky and bulky.
To make the robot toy, prepare the following materials:
The completed robot toy.
CUTTING LIST FOR THE ROBOT TOY
Part
L×W×T
Quantity Material
Body blank
100 × 45 × 45mm
1
Redwood
Body blank sides
100 × 45 × 10mm
2
Redwood
Head centre
60 × 55 × 45mm
1
Redwood
Jaw sides
70 × 40 × 6mm
2
Birch plywood
Jaw centre
45 × 20 × 20mm
1
Redwood
Eccentric cam
45 × 45 × 12mm
1
Birch plywood
Wheels
70 × 70 × 18mm
2
Birch plywood
Cam follower
85 × 9mm diameter dowel
1
Hardwood
dowel
Axle
65 × 9mm diameter dowel
1
Hardwood
dowel
Cam follower
guide block
40 × 15 × 12mm
1
Birch plywood
Upper arm
(walking action)
70 × 20 × 10mm
2
Redwood
Lower arm
(walking action)
100 × 20 × 10mm
2
Redwood
Upper arm
(marching action)
140 × 20 × 10mm
2
Redwood
Lower arm
(marching action)
100 × 20 × 10mm(use a 2mm welding rod for
the metal connecting rod)
2
2mm brazing
or welding rod
Antennae
35 × 6mm diameter dowel
2
Hardwood
dowel
Wooden beads
10mm diameter approx.
4
Hardwood
Handle
400 × 12mm diameter dowel
1
Hardwood
dowel
Handle hand grip
80 × 12mm diameter dowel
1
Hardwood
dowel
Arm spacer
10 × 18mm dowel
2
Hardwood
dowel
Nose
20 × 9mm dowel
1
Hardwood
dowel
FIXINGS NEEDED TO PRODUCE THE ROBOT TOY
Part
Fastening
Quantity
Jaw pivot
8-gauge × ¾in round-head, black Japanned screw with an
M4 washer
2
Shoulder pivot
8-gauge × 1¾in round-head screw
2
‘Elbow’ pivot
M4 lock nut and 25mm pan-head screw with two M4
washers. Screw/bolt head faces inwards to avoid jamming
on the robot’s jaw
2
on the robot’s jaw
Wheel pivot
8-gauge × ¾in round-head, black Japanned screw with an
M4 washer
2
Screw for fastening
eccentric cam wheel to
the axle
8-gauge × ¾in, countersunk-head woodscrew
1
The templates for the retro roving robot need to be enlarged to fill an A3 page.
Templates for the Robot Toy
The templates for the robot toy need to be enlarged on to an A3 piece of
paper in order to get the correct scale, proportion, and ratio of
components. The best method is to enlarge the templates until the
diameter of the wheel templates measure exactly 60mm.
Constructing the Robot Toy
Step 1: Shaping the body 1
1. Cut the centre piece for the robot body blank to measure 100 × 45 ×
45mm.
2. Draw diagonals to locate the centre of the top and the underside.
3. Try-square a line around the blank 55mm from the bottom.
4. Mark out the housing for the cam to the dimensions shown using a
marking gauge. The cam housing slot is 15mm in width, and is 55mm
from the base.
5. Drill out the hole for the cam follower using a 9mm drill bit.
Cut out the cam housing in the centre piece that forms the robot body, using the
dimensions shown.
6. Cut out the cam housing using a bandsaw or tenon saw.
7. Cut two pieces to form the back and front of the robot body (body
blank sides). These act to partially conceal the cam follower and
guide. Glue them over the front and back of the robot body blank to
conceal the cam and follower housing.
8. Paste on the robot body template to the timber blank and drill the hole
in the back for the handle. Set the robot toy body into the machine
vice, and angle it to meet the 12mm drill bit at the correct angle
shown on the paper template. Drill the hole to a depth of 20mm. Take
great care not to penetrate the cam follower housing or the body
shape will be useless.
9. Drill out the 10mm hole for the axle and the 3mm pivot point for the
arms. Take care to pack the cavity for the cam housing as the drill bit
is likely to split the timber as it passes through the cavity.
10. Centre punch and drill the locations for the axle hole, arm pivot
clearance hole and the location for the hole for a handle.
The main body component for the robot body contains an eccentric cam and a follower
that pushes the head up and down.
The two 10mm-thick front and back components act to partially conceal the cam and
follower components. They also serve to give the figure extra width to hold the handle and
allow for more interesting shaping.
Hold the robot body blank securely in the machine vice. Use a try-square to check for a
true vertical. The hole must be drilled no further than 20mm, as space is very limited in the
body blank. Eventually fit a 12mm dowel for a handle.
Step 2: Making the eccentric cam wheel
1. Use a compass to draw a 16mm radius circle on a piece of 12mm
thick birch plywood.
2. Mark the location for the 9.5mm axle hole 13mm in from the
circumference of the cam, and drill all the way through with a 9.5mm
drill bit.
3. Sand the waste wood away to leave the circumference of the
eccentric cam.
4. Drill a 3.5mm clearance hole on the circumference of the eccentric
cam to meet the 9.5mm axle location.
5. Countersink the clearance hole to receive a 6-gauge × ¾in
countersunk-head woodscrew.
Making the eccentric cam.
Step 3: Fitting the eccentric cam and axle to the body
1. Place the axle and eccentric cam externally over the axle area to
work out how much of the back and front needs to be removed to llow
the cam to rotate freely, while still concealing as much of the cam and
follower guide block as possible. Plot the highest point of the
eccentric cam’s rotation, and mark out how much of the body blank
sides at the front and the back needs to be removed to allow the cam
to rotate freely.
2. Use a tenon saw and file to carefully remove waste material.
The assembled robot body needs to allow the eccentric cam and guide block to rotate
freely while still concealing as much of it as possible.
3. Fit the axle, eccentric cam and follower into place to test for ease of
movement. Adjust as necessary with a file.
Step 4: Making the cam follower and guide block
The underside of the cam follower requires a guide block to prevent the
head rotating and falling out. The cam-follower guide block also helps
produce a smooth reciprocating head movement as the eccentric cam
rotates beneath it.
1. To produce the cam-follower guide block, cut a piece of birch plywood
40 × 15 × 12mm from birch plywood.
2. Centre punch the location of the cam follower, and drill out the centre
of the guide block using a 9mm drill bit. The hole needs to be centred
extremely accurately.
3. Chamfer or slightly radius the top edges of the cam-follower guide
block.
4. Glue the follower into the guide block and test it for ease of
movement in the robot body. Carefully sand away any tight areas.
Shape and drill the guide block that attaches to the underside of the cam follower to
prevent the head twisting and falling out. The follower and guide block assembly as
shown.
The follower and guide block reciprocate as the eccentric cam rotates, causing the robot’s
head to rise and fall.
Step 5: Assembling the robot body components
1. Glue the guide block to the underside of the cam follower. Place the
follower and guide block assembly into place, and test for a smooth,
accurate movement. Glass paper or file as necessary.
2. Place the wheel axle into place and screw the eccentric cam to it
securely. Test for quality of fitting. If the cam sticks or jams, you may
need to remove some material from the underside of the cam-follower
guide block. The axle should project equidistantly from either side of
the body to receive the wheels later.
Step 6: Making the head assembly 1
1. You can produce the head shape by pasting the template profiles on
to card or thin ply and using them to trace on to a 60 × 45 × 55mm
softwood blank. Each profile for the head has its own template.
2. Drill a 6mm diameter hole to a depth of 10mm for the robot’s head
antennae. You can make these holes for the antennae by using a
drilling jig made from a piece of timber with the appropriate angle cut
into it. Place the head blank on to the angled timber jig and clamp
both pieces into a machine vice.
3. Drill a 9mm diameter hole to a depth of 15mm on the underside of the
head to receive the cam follower.
4. Drill a 3mm diameter pilot hole all the way through to receive the
robot head jaw.
5. Drill a 9mm or 12mm diameter hole to a depth of 15mm for a nose.
6. Drill a 9mm diameter hole to a depth of 15mm for eyes.
7. After all holes are drilled, complete the basic head shape by cutting
the side profile, then glass paper/sand.
8. Cut a 9mm or 12mm dowel to a length of 20mm to form the nose.
9. Cut two 9mm dowels to a length of 15mm to form the eyes, or use
two 10mm wooden beads.
10. Cut two 6mm dowels to a length of 30mm to form the head antennae,
and tap them into place.
Stages involved in making the robot’s head.
Step 7: Making the head assembly 2: making the robot’s
jaw
1. Paste the jaw profile on to card or plywood to form a template.
2. Cut two jaw sides, and make a centre piece measuring 42 × 20 ×
20mm.
3. Glue the jaw sides and centre piece to form the jaw shape, as shown.
Line the edge of the jaw profile up to the furthest edge of the centre
piece on both sides.
4. Leave the glue to set slightly, and then clamp the jaw assembly in a
vice to dry. Make sure the parts don’t slide out of position.
5. Drill out the 4.5mm holes for the jaw pivot. Drill the assembly together
to avoid holes not lining up. Use a scrap piece of 44 × 44mm to pack
the cavity between the jaw so it doesn’t snap during drilling.
6. Sand and glass paper the centre piece to follow the contour of the jaw
front edges. The curve is important as it allows the jaw to open and
close easily as the head rises and falls.
7. Temporarily fit the jaw to the robot’s head and test for ease of
movement. The head should rise and fall smoothly and easily as the
axle is rotated, causing the eccentric cam to reciprocate.
8. Gravity causes the head to return to its original position. Glass paper
the head and jaw to reduce surface friction and sticking.
9. Fit the 20 × 9mm dowel to form the nose. You could also use a piece
of 12mm dowel.
10. Countersink the eye areas to receive the wooden beads for eyes, or
use dowel.
11. Expand the holes in two 10mm wooden beads to be fixed to the ends
of the head antennae.
Stages involved in making the robot’s jaw.
Temporarily fit the completed jaw to the head using two 8-gauge × ¾in round-head, black
Japanned screws. Fit the completed head and jaw assembly to the robot body and test by
rotating the axle to check the head rises and falls smoothly.
Fit the eyes, nose and antennae to the completed robot’s head.
Step 8: Making the wheels
1. Make two wheel blanks measuring 70 × 70 × 18mm.
2. Use a compass to draw a 30mm radius circle on both sides of each
wheel blank.
Find the centres of each wheel blank by connecting the diagonals with a pencil. Use a
compass to draw a 60mm diameter circle circumference.
3. Use a centre punch to mark the location for the axle holes and the
pilot holes for connecting the arms to the wheels. The axle hole is
9mm, the pilot hole for the arm connection is 3mm.
4. Use a machine vice to hold each wheel blank securely. Drill the axle
hole to a depth of 15mm using a 9mm drill bit.
Set the depth stop to drill an axle hole to a depth of 15mm.
5. To make the pivot point for the connecting rods attached between the
wheel and the arms, mark a 2.5mm pilot hole 10mm from the edge of
the circumference of each wheel, and drill to a depth of 10mm. Drill
from the front of each wheel with the axle hole facing at the back or
downwards.
The pilot holes for the arm connecting-rod pivots are drilled 10mm from the front of each
wheel to a depth of 10mm.
6. Rough out the wheels using a tenon saw or the bandsaw. Don’t
attempt to cut to the wheel circumference. Leave some waste.
Remove the corners from each wheel blank, but do not attempt to cut up to the
circumference.
7. Complete the wheel’s circumference using the sander. Each wheel
should have a 9mm axle-hole wheel on one side and a 3mm pilot
hole for the arm connecting rod on the other. Radius the
circumference of both wheels with glass paper.
8. Once all components are complete and ready to assemble, screw the
eccentric cam to the axle using a 2.5mm pilot hole.
Use the sander to remove all the remaining waste material from the wheel’s circumference.
The cutting list and dimensions for the robot’s arms are shown. Note: if you want to make
the marching action that uses a metal connecting rod, you will not need to make two of
part B.
When finally assembling all components, fix the eccentric cam into place by holding the
robot body shape upside down in a vice.
The assembled axle and wheels will look like this.
Step 9: Making the arm components
1. Choose which robot movement type you want to make: walking or
marching?
Cut the arm sections to length, and centre the location of the pivot points by scribing with
a marking gauge to find the centre. Radius the ends and all edges.
2. Use the cutting list illustration to prepare the arm sections you will
need.
3. Cut the arm components to length, and mark out the location for the
pivot points.
4. Centre punch the location for the holes and drill them to the required
diameters.
5. Round over the ends of each arm section using a penny coin or
similar to get the correct radius.
6. Glass paper and radius all edges and surfaces.
7. Prepare two spacer blocks of 25mm dowel cut to 12mm in length.
These will be used to project the arms from the surface of the body to
line up parallel with the fronts of the wheels.
Step 10: Making and fitting the arm components for a
walking-action robot
1. Assemble two pairs of parts B and C to form the walking-action arms.
Join the ‘elbow’ joints with two sets of M4 lock nuts and the 25mm
pan-head screws with two M4 washers.
Assemble a pair of parts A and B to form the walking-action arms. Make the lock nuts face
outwards to prevent catching against the robot body. Hacksaw and file the edge of the bolt
smooth.
2. Place a spacer block between the shoulder join and the top of the
arm.
The spacer block causes the arm to line up in parallel with the exterior of the wheel.
3. Screw the arm into place at the shoulder join using an 8-gauge × 1¾
inch round-head screw.
4. Repeat the process to locate the second arm.
5. When the wheels are finally glued into place, the pilot holes for fixing
the lower arm to the wheel must be synchronized to cause an
alternate rise and fall of each arm to create the walking illusion.
6. When all the parts are finished, decorated and sealed, join the lower
leg to the wheel with an 8-gauge × ¾in round-head, black Japanned
screw with an M4 washer.
Step 11A: Making and fitting the arm components for a
marching-action robot
There are two ways to produce the marching action robot arms. The first
uses a wooden connecting rod (part B), shown on the dimensioned arms
cutting list that connects the arm to the wheel. The second method uses
a metal connecting rod formed from a 2mm brazing rod (in place of part
B). The metal connecting rod is more discrete and causes the robot toy to
look less like a deckchair on wheels.
1. Assemble two pairs of parts A and B to form the walking-action arms.
Then join the ‘elbow’ joints with two sets of M4 lock nuts and the
25mm pan-head screws with two M4 washers.
2. Place a spacer block between the shoulder join and the top of the
arm.
3. Screw the arm into place at the shoulder join using an 8-gauge ×
1¾in round-head screw.
4. Repeat the process to locate the second arm.
5. When the wheels are finally glued into place, the pilot holes for fixing
the lower arm to the wheel must be synchronized to cause an
alternate rise and fall of each arm to create the marching illusion.
The pilot holes on the exterior of the wheels must be synchronized to cause a rise and fall
effect, or walking action as the individual arms rise and fall alternately.
Two methods or types of connecting rod for joining the arms to the wheels.
Step 11B: Making and fitting the marching arm using a
metal connecting rod
1. The metal connecting rod is formed from a 2mm-diameter brazing rod
with an 80mm space between the looped ends.
2. A simple bending jig could be formed from some 6mm diameter round
steel and some 25mm flat bar. Alternatively you could use larger, long
nose pliers to form the connecting rod.
3. Place the 2mm rod between the 6mm pegs of the bending jig, as
shown. Bend the wire around the 6mm pegs individually to form the
loops at each end. Make sure you bend the wire as close to the point
where the wire meets the peg in order to avoid excessive curvature.
Make a tight turn and twist.
4. Lift the wire shape off the bending jig and use a hacksaw to cut off the
waste.
5. Crush out the excessive curvature in the rod by clamping it in the
vice. Twist the ends of the loops to form a circle on the ends using
long-nose pliers.
6. Use a hacksaw to cut through the end of each loop in the location and
direction of the arrow. Cut through the wire where the long straight
edge meets the loop.
7. Use long-nose pliers to adjust the angle of the loop on the end of the
connecting rod. Close the ends of the loops by crushing them
carefully in the jaws of the vice.
8. Use a ball-pein hammer to slightly flatten the ends of the connecting
rod. This makes it fit better, and work hardens the ends to withstand
bending.
9. Use emery cloth and files to prepare the surface of the connecting rod
for painting. Fasten one end of the connecting rod to the ‘elbow’ of
the robot arm using an M4 lock nut and a 25mm pan-head screw with
two M4 washers. Fasten the lower end of the connecting rod to the
wheel pivot point using an 8-gauge × ¾in round-head, black
Japanned screw with an M4 washer. Make sure the wheels are
synchronized to generate a lift and fall for each arm for every
revolution of the axle.
Step 12: Making the handle
The handle for the robot toy is a 12mm dowel set to a depth of 20mm into
the back of the robot toy. The angle for drilling the handle hole is drawn
on to the template for the robot body. The method for drilling out the
angled hole is described in step 1, stage 8. The handle should be cut
from a 12 × 500mm length of dowel. A simple hand grip can be formed
from a piece of 25mm dowel cut to a length of 90mm. Drill a 12mm hole
to a depth of 15mm in the centre of the hand grip in order to fix at a right
angle to the shaft of the handle. A Forstner drill bit would be ideal for this
task.
Follow the location for the robot handle on the profile template for the body, and ‘dry fit’.
Step 13: Finishing, decorating and assembly
1. When all components are completed and rubbed down with 80-grit
glass paper, followed by 120-grit, 240-grit and finally a 1,200-grit for a
super smooth surface, stain them to the colours required using a
spirit-based stain made from surgical alcohol and edible food dye.
Leave the components for a day or two for the spirit to evaporate
completely. Individual details can be painted in separate colours
using enamel paint.
2. The example shown has decoupaged details printed and pasted on to
3.
4.
5.
6.
it using PVA. To make the details, draw or collage a design on the
computer, and print it in colour on to cartridge paper. Cut out the
design and paste it on. Look for inspiration from the mechanical tin
toy examples from the 1950s and 60s. Again, experimentation is the
key to success.
Once dry, the components can be sealed with sanding sealer or
cellulose lacquer for a more hard-wearing surface.
Glue the handle into place once the components are dry, and glue the
handle hand grip to the top of the handle.
Assemble all the components for the final time using PVA where
required.
Paint and glue in the beads or dowels for the eyes and nose with a
two-part epoxy adhesive.
CHAPTER NINE
THE CRANKY CROCODILE
The Cranky Crocodile snaps and waddles along with enough character
and menace not to be too twee. Children love him, and shriek with a
mixture of fascination and fear as he ambles towards them.
The crocodile toy uses the same inside peg technique as the dog toy.
A peg on the interior of the front wheels flips the head up and down to
create the snapping action. With careful shaping the jaws will make a
satisfying snapping sound as they close. The head is sculpted to give the
reptilian texture and appearance of a crocodile, with the addition of teeth
made from 4mm dowels set into drilled sockets in the toy’s mouth.
The legs use the outside wheel peg and pivot technique to create the
impression of walking. The finishing touch is an articulated tail made from
softwood strips bonded to a heavy canvas interface. The blocks are
dried, shaped and sculpted to form a tail that flops from side to side as
the crocodile is moved.
The completed crocodile toy uses the inside wheel peg technique to make the snapping
action as he is pushed along. Gravity returns the jaw to the closed position, making two
snapping actions for every rotation of the axle. The legs use the outside wheel pivot
technique to make the walking action.
To make the crocodile toy, prepare the following materials:
CUTTING LIST FOR THE CROCODILE TOY
Part
Reference L × W × T
Quantity Material
Body blank
A
300 × 90 × 20mm
2
Redwood
Head centre
C
120 × 50 × 40mm
1
Birch
plywood
Head/jaw sides
B
150 × 100 × 9mm
2
Birch
plywood
Wheel blanks
60 × 60 × 20mm
4
Redwood
Front axle
100 × 9mm
diameter dowel
1
Ramin
dowel
Rear axle
75 × 9mm diameter
dowel
1
Ramin
dowel
Front axle spacers
25mm diameter
dowel × 15mm
2
Ramin
dowel
Rear axle spacers
25mm diameter
dowel × 5mm
2
Ramin
dowel
Upper front leg spacers
18mm diameter
dowel × 30mm
2
Ramin
dowel
Upper back leg spacers
18mm dowel ×
20mm
2
Ramin
dowel
Inside wheel pegs for
front wheels only
25 × 9mm diameter
dowel
2
Ramin
dowel
Head axle/pivot
4mm diameter
dowel × 80mm
1
Ramin
dowel
Tail pieces
100 × 20 × 20
24
Tail interface
240 × 120mm
1
Eyes
4mm hardwood
beads
2
Handle
400 × 18mm
diameter dowel
1
18mm
dowel
Handle hand grip
95 × 25mm
diameter dowel
1
25mm
dowel
100 × 50 × 9mm
2
Birch
Lower front legs
D
Redwood
Heavy
canvas
Lower front legs
D
100 × 50 × 9mm
2
Birch
plywood
Upper front legs
E
80 × 35 × 20mm
2
Redwood
Lower back legs
F
90 × 65 × 9mm
2
Birch
plywood
Upper back legs
G
90 × 45 × 20mm
2
Redwood
FASTENINGS LIST FOR THE CROCODILE TOY
Part
Fastening
Qty
Shoulder Pivot
8-gauge × 1¾in round-head screw
2
‘Elbow’ Pivot
M4 locknut and 25mm pan-head screw with two M4 washers
2
Wheel Pivot
8-gauge × ¾in, round-head, black Japanned screw with an M4 washer
2
Templates for the Crocodile Toy
The templates for the crocodile toy need to be enlarged on to an A3
piece of paper in order to get the correct scale, proportion and ratio of
components. The best method is to enlarge the templates until the
diameter of the wheel templates measures exactly 55mm.
The templates for the crocodile toy are labelled to correspond to the cutting list. The tail is
shown separately for practical purposes.
Step 1: Making the body
1. Cut out two 20mm thick body profiles (A) and glue them together to
form the thickness required. Use the first cut-out profile as a template
to make a second.
2. Once the body shape has dried, drill out all the holes to the required
diameters.
3. Expand the ‘shoulder’ holes to a depth of 15mm using an 18mm
diameter Forstner bit. These holes will receive the 18mm spacer
piece to project the upper legs away from rubbing against the body
and to line up the front legs in parallel with the wheels.
4. Drill out a 12mm hole for the handle to a depth of 30mm. Place the
crocodile body at an angle in the machine/hand vice for the pillar drill.
Use the dashed line on the body template and a try-square to set up
the body blank at a true vertical. Make sure to centre punch the
location of the hole first.
The tail join is strengthened by pegging it using 6mm fluted dowels. Mark out and drill the
holes 10mm in from the sides, and 15mm in from the top and bottom.
5. Mark out and drill four 6mm holes in the rear of the crocodile toy’s
body to receive fluted dowel pegs for gluing the tail on to the body. It
is important that the body is mounted vertically. Drill the holes to a
depth of 10mm.
The location of the 2.5mm fixing points for the upper legs is expanded to 18mm to receive
the spacers upon which the upper legs will pivot.
Step 2: Making the head
The head is a kind of bell crank operated by two internal wheel pegs
placed within the front wheels. It works in exactly the same way as the
head of the frog and dog toys.
1. Cut out the two head sides (B) from 150 × 100 × 9mm birch plywood.
2. Cut out the head centre (C) from a laminated block of birch plywood
measuring 120 × 50 × 40mm. Five layers of 9mm-thick birch ply will
suffice. A 5mm thickness will need to be removed later.
3. Glue the head assembly together, making sure the head centre
measures slightly over 40mm in thickness before assembly. Allow the
components to set slightly before clamping, and then check they do
not slide out of position when clamped.
4. Once dry, drill out the completed head assembly to receive the head,
the 4mm head pivot point, and the 4.5mm location for the eye
sockets. Countersink the eye locations.
The completed head blank before shaping.
Rounding over and shaping the crocodile head and lower jaw.
Sculpting the details of the head, jaw and body. The image shows the crocodile’s head and
body after shaping.
Step 3: Shaping the head and body
1. Peg the head assembly temporarily to the body with a 4mm dowel.
Draw the basic tapered profile required for the final head form, then
use a bandsaw and a 140mm drum sander with an 80-grit paper to
remove the bulk of the waste. Round over the front end and the head
contours. The finer detailing and shaping are done with rotary cutting
tools. Refer to Chapter 6, which demonstrates the frog toy, for extra
guidance.
2. Trace round the crocodile’s upper jaw where it makes contact with the
lower jaw to guide the contours required for the front of the crocodile’s
lower jaw. Remove the head and round over the contours of the
crocodile’s head and body using the same process and technique as
the frog and dog toy. Begin with an 80-grit paper fitted to a 140mm
drum sander, and move to finer shaping with different diameter rotary
cutting tools.
3. Use the 140mm drum sander with an 80-grit paper to sculpt the
crocodile’s body. The process for shaping the crocodile’s head and
body are the same as the process used to shape and form the frog
and dog toy in the earlier chapters.
4. The finer details and shaping for the head are carried out using a
range of rotary cutting tools. While you are not making a model for the
natural history museum, it’s worth looking at a crocodile head to get
the basic dimensions and features. Attempt to capture some of the
subject’s basic characteristics and menace. Later you will add some
teeth made from 4mm dowel to complete his ruthless reptilian grin.
5. Use rotary tools to carve some of the folds, creases and cracks in the
crocodile’s head and body.
6. Mark out the location for about ten teeth made from 4mm diameter
dowel. Locate them in such a way that some of them overhang to
give the reptilian overbite. Drill the sockets for the teeth using a 4mm
drill bit. Let some of the teeth hang over or outside the mouth area,
just like its crocodilian cousins.
7. Use the rotary cutting tool to hollow out the interior of the crocodile’s
upper and lower jaw to accommodate the teeth, taking care not to
accidentally open the tooth sockets. Remove enough material to
allow the teeth to close over each other.
Step 4: Shaping and fitting the tail
The flexible tail is made from angled timber strips glued adjacent to each
other on both sides of a heavy canvas interface. Once dry, the strips will
allow movement dictated by the angle cut on to the sides of the timber
strips. A 5-degree angle is enough to allow for movement; any wider and
the timber blocks tend to pinch the fingers.
1. Cut a 5-degree angle on both sides of a long length of softwood
measuring 20 × 20mm in section. Eventually you need to have
twenty-four 100mm lengths to form the tail.
Side profile of the template used for making the tail. Enlarge the template until it measures
220mm in length.
Carefully line up twelve timber strips either side of the canvas interface. Leave to dry for
about six hours in a warm place.
2. Cut a piece of heavy canvas measuring 240 × 120mm.
3. Carefully glue a row of twelve strips of the 100 × 20 × 20mm timber
strips on to one side of the canvas. Spread wood glue evenly and
carefully, taking care not to allow gaps between the strips. Leave the
assembly to dry off for an hour or so, and rotate it to repeat the
process with another twelve timber strips on the other side of the
canvas. Take care that all the strips line up on both sides. Leave the
completed tail assembly to dry for several hours.
4. Place 6mm copper dowel pins into the holes previously drilled into the
crocodile’s body, and press the tail assembly against the pins to
locate the position for the second set of holes to receive the dowel
pegs. The dowel pins will leave an indentation used to locate the
position for the second set of holes to be drilled in the tail assembly.
Mount the tail into a pillar drill and drill to a depth of 10mm. Insert the
dowel pegs and ‘dry fit’ the tail and body together temporarily in order
to locate the tail profile template accurately.
Use the copper dowel pins to locate the position for the second set of 10mm deep holes to
complete the dowel join between the crocodile body and tail.
Place the tail template over the tail blank and trace its contours in the correct position. Cut
the profile with a bandsaw.
After cutting the external profile, use the bandsaw to taper the tail profile from the front to
the tip.
Use a 12mm rotary sander to cut the grooves, ridges and recesses to make a really
reptilian tail.
5. Place the tail template over the front of the tail blank and trace round
it. Cut out the tail profile.
6. Use a bandsaw to cut the tail so it tapers, or diminishes in width as it
moves away from the point where it is joined to the body. Measure
approximately 8mm each side of the tail tip, and connect with a
straight-edge to the point where it connects to the crocodile’s body.
Bandsaw the waste away.
7. With the tail pegged to the crocodile’s body, use a 140mm drum
sander to sculpt the tail and blend the body and tail assembly
together.
8. Glue the tail into place, and glass paper all the components,
beginning with an 80-grit paper, progressing to a 240-grit, and
completing with a 1,200-grit. The tail may need some manipulating to
loosen it up.
Step 5: Making the wheels
The wheels are 55mm in diameter with a 2.5mm-diameter pilot hole
drilled on the exterior of each wheel, located 15mm in from the
circumference. The 2.5mm pilot hole is the fixing/pivot point for each leg
assembly. In order to create the walking action, the holes need to be
located one at the top and one at the bottom of each wheel in order to
create the lift and fall action for each rotation of the axle.
Inside just the front wheels is a 9mm hole located 10mm from the
circumference for a 9mm dowel peg: as the front wheels rotate, this will
lift the jaw. Locate the 9mm hole for the interior wheel peg at the opposite
end of the circumference to the 2.5mm exterior pilot hole for fixing the
front leg assemblies. Use a centre punch to locate each hole accurately
for the drill bit after marking out.
1. Begin making the wheels by locating the centre of each wheel blank.
Use a ruler to connect the diagonals, and a compass to draw a
55mm-diameter circle. Repeat to locate the centre and circumference
on the other side of the wheel blanks.
2. Select a pair to form the front wheels, and mark out the location for
the interior pegs, 10mm from the circumference. Drill a 9mm hole to a
depth of 10mm.
3. Drill the 9mm holes to receive the axles to a depth of 15mm on all
four wheels. It is essential that the interior wheel pegs face inwards
on the completed axle assembly.
The front and rear axles assembled. The front axle has two 9mm inside wheel pegs to flip
the head up and down. All four wheels have spacers cut from 25mm dowel to stop the
wheels jamming or rubbing against the body. The spacers also project the wheels to line
up in parallel with the wheels.
4. Turn the front wheels over and mark out the location for the 2.5mm
pilot holes, 15mm from the circumference for the leg pivot points. Drill
to a depth of 15mm.
5. Repeat on the exterior of the rear wheels (these do not need the
interior wheel pegs).
6. Remove the waste from the wheel blanks until they are completely
circular.
7. Cut a front axle measuring 100 × 9mm diameter from dowel.
8. Cut a rear axle measuring 75 × 9mm diameter from dowel.
9. Bore a 10mm hole through a section of 25mm diameter dowel, and
cut two 15mm lengths to form the spacers that will slide over the
axles to prevent the internal wheel pegs jamming against the side of
the crocodile’s body. Repeat to form two 5mm lengths to make the
spacers needed for the rear wheels.
10. Cut two internal front-wheel pegs from 9mm dowel to a length of
25mm, and press into their locations on the inside of both front
wheels. (It is better to sand and finish the wheels before gluing the
inside wheel pegs into place.)
Step 6: Fitting the pivot points for the crocodile’s upper
legs
1. Make two 30mm lengths of 18mm-diameter dowel, and tap them into
the front upper leg location for the front legs to pivot from. You could
think of them as the front shoulder location.
2. Make two 20mm lengths of 18mm-diameter dowel, and tap them into
the rear upper leg location for the rear legs to pivot from. You could
think of them as the hips, or rear leg location. After all glass papering
is complete, glue in the leg spacer/pivot points.
Step 7: Assembling the legs
1. Assemble two pairs of front legs (parts D and E) using an M4 lock nut
and 40mm pan-head screw with two M4 washers. Then screw/bolt
head faces outwards. For the final assembly, use a hacksaw to cut
away the protruding length of the bolt, and file smooth.
The legs are assembled and joined to the body as shown. The image also displays the
upper leg pivot points projecting from the ‘shoulder’ joins.
2. Assemble two pairs of rear legs (parts G and F). Again, use an M4
lock nut and 40mm pan-head screw with two M4 washers. The
screw/bolt head faces inwards to avoid the screw jamming on the
crocodile’s body. For the final assembly, use a hacksaw to cut away
the protruding length of the bolt, and file smooth.
3. Locate the centre of all four of the leg spacers on which the upper
legs will pivot, and drill a 3mm pilot hole to receive a 10-gauge × 1¾in
round-head screw.
4. Dry fit the whole crocodile assembly to test for accuracy and ease of
movement. Remember the ‘one up, one down’ configuration for the
pivot points on the exterior of the wheels.
Step 8: Finishing and painting the crocodile toy
1. As with previous projects, make sure to glass paper and prepare
components before painting and decorating them. All parts should be
sprayed with grey primer/ undercoat to seal the surface before
spraying. Once dry, rub down the components with 240-grit glass
paper to remove any raising of the grain, and to give a smooth
surface before applying the colour.
2. Spray all components with a dark, chocolate-brown base colour.
3. This may seem weird, but wrap a pair of fishnet stockings over the
crocodile body and components: when you spray the paint, the
fishnet stockings will act as a mask and leave a fantastic reptilian,
scaly skin effect. Check with the owner of the stockings before using
them, although I am told that stockings with a suitable pattern are
cheaply and easily available. When I bought mine explaining their
intended purpose, I was greeted with a curious look by a rather
matronly and less-than-convinced shop assistant. You could also use
those net-like bags in which oranges and lemons are sold, to create a
lovely mottled, textured effect.
4. First spray the model a dark green colour and leave to dry. Add a
lighter green over convex areas and edges. The dark chocolatebrown first coat will give depth to the colour and appear as the cracks,
creases and folds in the crocodile’s skin.
5. Finally, spray the underside with a creamy, ochre-like colour.
6. Paint the eyes with a yellow colour and add a diagonal pupil to get
that cold, relentless, reptilian gaze.
7. When all components are stained and sprayed, seal them with clear
cellulose or acrylic lacquer. When this has dried, give the components
in contact with each other a coat of wax, and polish them later to
reduce surface friction.
8. Make a set of teeth from 4mm dowel, and glue them into the sockets
prepared earlier. Some can be longer than others to make the
attractive overbite that crocodiles have. Obviously don’t sand and
shape them into a point.
9. Glue the handle into place once the components are dry, and glue the
handle hand grip to the top of the handle.
10. Assemble all components for the final time using PVA where
required.
CHAPTER TEN
THE ROAMING RAPTOR
The raptor uses a linkage mechanism to cause the head to
simultaneously lunge up and down as the jaws snap open and shut. A
cavity inside the abdomen contains an eccentric cam to drive the head
mechanism as the wheels rotate. Gravity keeps the head assembly in
constant contact with the eccentric cam wheel. When you push or pull
him, he charges along on legs connected to the wheels similar to those in
the previous chapters, and makes a lovely snap sound as the jaws shut.
The grasping forearms hang freely, waiting to grab his prey. The figure is
completed with an articulated tail similar to the crocodile, which swings
from side to side as the figure is pushed and pulled along. The addition of
some 4mm dowel teeth complete his air of reptilian menace.
The completed roaming raptor toy.
To make the Raptor toy, prepare the following materials:
CUTTING LIST FOR THE ROAMING RAPTOR TOY
part
Reference LxWxT
Qty Material
Body blank
A
170 × 130 ×
20mm
2
Redwood
Head sides
C
110 × 70 ×
20mm
2
Redwood
Head centre
F
80 × 40 × 20mm
1
Redwood
Lower jaw sides
G
70 × 30 × 20mm
2
Redwood
Lower jaw and head lever
B
200 × 150 ×
18mm
1
Birch
plywood
Upper body spacer
D
140 × 80 ×
20mm
2
Redwood
Lower body spacer
E
60 × 70 × 20mm
2
Redwood
Eccentric cam wheel
K
45 × 45 × 20mm
1
Birch
plywood
Wheel blanks
L
80 × 80 × 20mm
2
Redwood
Lower leg
J
110 × 60 × 9mm
2
Birch
plywood
Upper leg
I
90 × 50 × 20mm
2
Redwood
Head lever /linkage pin
(through the body)
60mm diameter
dowel× 70mm
1
Birch
plywood
Head linkage pin (through the top of the body
and the connecting rod)
4mm dowel ×
55mm
1
4mm
dowel
Head linkage pin (joining the connecting rod
to the top of the head)
4mm dowel ×
55mm
1
4mm
dowel
Jaw pivot connecting the lower jaw to the
head
4mm dowel ×
55mm
Connecting rod between the head and body
55 × 20 × 12mm
1
Birch
plywood
Tail pieces
100 × 20 ×
20mm
24
Redwood
Canvas tail interface
240 × 100
Rear leg spacer blocks
25 × 25mm
diameter dowel
2
25mm
dowel
Front leg spacer blocks
20 × 20mm
diameter dowel
2
20mm
dowel
Handle
400 × 18mm
diameter dowel
1
18mm
diameter
dowel
Handle hand grip
100 × 25mm
diameter dowel
1
25mm
diameter
dowel
4mm
dowel
Canvas
FASTENINGS LIST FOR THE ROAMING RAPTOR TOY
Part
Fastening
Qty
Pelvis pivot
10-gauge × 1in round-head screw
2
Pelvis pivot
10-gauge × 1in round-head screw
2
‘Knee’ pivot
M4 lock nut and 40mm pan-head screw with two M4 washers.
Screw/bolt head faces inwards to avoid jamming on the dinosaur’s
jaw
2
Wheel pivot
10-gauge × 1in round-head, black Japanned screw with an M4
washer
2
Shoulder pivot
for
the front legs
10-gauge × 1¼in
Templates for the Roaming Raptor Toy
The templates for the raptor toy need to be enlarged on to an A3 piece of
paper in order to get the correct scale, proportion and ratio of the
components. The best method is to enlarge the templates until the
diameter of the wheel measures exactly 70mm.
The templates for the roaming raptor toy are labelled to correspond to the cutting list.
Step 1: Shaping the body
1. Paste the components for making the body on to a 20mm-thick piece
of redwood using a glue stick. You will need to make two of part A to
form both sides of the raptor’s body; the centre is made by gluing
parts D and E to form a cavity in which the head lever and the
eccentric cam are located.
2. Take one part A (one side of the raptor’s body). Use a compass point
or bradawl to make a series of pin pricks to locate the position of the
internal spacer components (parts D and E).
Paste the body templates on to a 20mm-thick redwood board.
Use pin pricks made with a compass point or bradawl to locate the position of the internal
spacer components.
3. Glass paper the template away and draw in the location for parts D
and E: a good old-fashioned join-the-dots exercise. Refer to Chapter
4 ‘Tips and Techniques’ for additional help.
4. Cut out and glue Parts D and E into position and leave to dry.
Remember to remove the paper templates before gluing.
Glue in the spacer blocks to form the cavity in which the eccentric cam and head lever are
located. It is easier to cut out the head lever and cam wheel to test for ease of movement
before the second half of the body is glued into place. The adjustments can be made using
a bandsaw and sander.
The handle projects from the back at roughly 60 degrees, and the hole to receive the
handle must be drilled before the body is shaped and sculpted.
5. Take the second part A with the paper template facing upwards. Use
a centre punch to locate all the locations for the holes needed.
6. Glue the second body side (part A) into place and leave to dry.
7. Drill out the assembled body component to the required diameters
shown on the paper template. Drill all the way through the body blank.
8. Remove the paper template with glass paper.
9. Mark out the location for the 12mm handle by mounting the body
blank into a machine or hand vice using the dashed location line
projecting upwards at a true vertical. Make sure the body is exactly
parallel to the edge of the pillar drill bed to avoid accidentally drilling a
compound angle. Use a try-square to align it correctly. Drill to a depth
of 25mm.
10. Expand the location holes for the legs and arms using an 18mm
Forstner bit to a depth of 15mm. These holes will receive the spacer
blocks that keep the arms and legs off the surface sufficiently to sit
square and parallel with the wheels, and not rub against the surface
of the body.
The location for the pivot points for the arms and legs. Expand the holes already drilled to
the required depth using an 18mm Forstner bit.
The tail pegs to the raptor toy’s body in exactly the same way as the crocodile toy’s tail.
Use 6mm fluted dowels, and drill all holes to 10mm.
The sequence for sculpting and forming the raptor’s body. Use a 140mm drum sander and
progress to a 25mm to form the ridges and smaller concave areas.
11. Drill four equidistant holes in the rear of the body assembly to a depth
of 10mm to receive four 6mm fluted dowels to peg the tail to the body.
Place the holes 15mm in from the outside edges of the body
assembly, and 30mm apart. Use a marking gauge and try-square to
help position the holes accurately.
12. Rough out the final form for the raptor using a 140mm drum sander
fitted with an 80-grit abrasive paper. Begin by rounding over the
edges and then forming a curve at the rear to receive the tail. Use a
smaller drum sander to cut in the ridges across the back.
13. Take care not to radius the wheel location excessively as this might
affect the toy’s stability. Radius just the immediate edges and the
surfaces near the wheel locations.
Step 2: Making the tail
The tail is made in exactly the same way as the tail for the crocodile toy
in the previous chapter. Softwood strips with a 5-degree angle cut along
their adjacent edges are bonded on both sides to a heavy canvas
interface. Once dry, the assembly can be cut and sculpted to form a
flexible tail.
Label each strip with ‘T’ for top so you glue them facing upright correctly. When dry, use
the template to cut the tail profile, and then cut a taper towards the end of the tail.
1. Cut a 5-degree angle on both sides of a long length of softwood
measuring 20 × 20mm in section. Eventually you need to have
twenty-four 100 × 20 × 20mm lengths to form the tail.
2. Cut a piece of heavy canvas measuring 240 × 100mm.
3. Carefully glue a row of twelve of the 100 × 20 × 20mm timber strips
on to one side of the canvas. Spread the wood glue evenly and
carefully, taking care not to allow gaps between the strips. Leave the
assembly to dry off for an hour or so, then rotate it to repeat the
process with another twelve timber strips on the other side of the
4.
5.
6.
7.
8.
canvas. Take care that all the strips line up on both sides. Leave the
completed tail assembly to dry for several hours.
Place 6mm copper dowel pins into the holes drilled into the raptor’s
body, and press the tail assembly against the pins: this will show you
where to locate the holes for the dowel pegs. The copper dowel pins
will leave an indentation, which will indicate where to drill the second
set of holes in the tail assembly. Mount the tail into a pillar drill, and
drill to a depth of 10mm. Insert the dowel pegs and ‘dry fit’ the tail and
body together temporarily in order to locate the tail profile template
accurately.
Place the tail template over the front of the tail blank and trace around
it. Cut out the tail profile.
Use a bandsaw to cut the tail so it tapers, or diminishes in width as it
moves away from the point where it is joined to the body. Measure
approximately 8mm each side of the tail tip, and connect with a
straight-edge to the point where it connects to the raptor’s body.
Bandsaw the waste away.
With the tail pegged to the raptor’s body, use a 140mm drum sander
to sculpt the tail, and blend the body and tail assembly together.
Glue the tail into place and glass paper all components, beginning
with an 80-grit paper, progressing to a 240-grit and finishing with a
1,200-grit.
Step 3: Making the head
The head is a linkage mechanism connected to an eccentric cam located
in the abdomen between the wheels. A connecting rod between the top
of the body and the head allows the head to lunge forwards and back
while simultaneously creating a snapping action of the jaws. Cut out part
B from 18mm-thick birch plywood, or two layers of 9mm bonded together
to make up the thickness.
1. Cut out two part G components to form the lower jaw. Glue them one
on each side of the front of the lower jaw using the dashed line to
align to the rear of their location.
2. Cut out part F (the head centre) from a 20mm-thick block made from
birch plywood.
3. Glue the head sides (part C) one on each side of the head centre,
4.
5.
6.
7.
and clamp until dry.
When the head components are dry, drill out all the holes to the
required diameters. Pack the interior of the head/upper jaw to prevent
the timber tearing.
Mark out the location for the eyes, and drill a 3mm hole to a depth of
10mm for each eye. The holes will then need to be expanded with a
countersink bit to receive wooden beads for eyes.
Peg the head to the head lever with a 4mm dowel, and test for
accuracy and ease of movement. Adjust as necessary with a file and
glass paper.
Place the head assembly into the body cavity through the neck area
and temporarily peg it into place with a 6mm dowel. Again, test for
accuracy and ease of movement. It may be necessary to remove
some of the width of the head lever to allow for maximum movement
if it traps too easily against the interior spacer blocks (parts D and E).
Dismantle the head and body assembly.
The sequence for shaping the head and lower jaw using drum sanders and rotary cutting
tools.
Step 4: Shaping the head
1. Remove the upper head assembly and use a 140mm drum sander to
reduce the width of the head, and cut a concave area into both sides
of the lower jaw and lever component.
2. Place the upper head components over the jaw, and pencil in a rough
profile to guide the orbital sander to complete roughing out the upper
head. If not completed already, expand the eye locations using a
3.
4.
5.
6.
countersink bit, and cut the remaining concave areas using a rotary
cutting tool. Cut two nostrils using a rotary rasp fitted to the cutting
tool.
Mark the location for about ten 4mm teeth made from dowel. Make an
overbite by shaping the lower jaw to allow the teeth to overhang to a
length of about 5mm. Drill the holes for the teeth to a depth of 5mm.
Place the teeth into their sockets when all assembly and finishing is
completed.
Hollow out the upper jaw with a rotary cutting tool to accommodate
about six teeth in the lower jaw. Drill out the holes as near as possible
to the edge of the lower jaw, whilst still allowing the jaws to close
easily. Some extra sanding and shaping may be required to achieve
this. They don’t have to be perfectly symmetrical dentures – just think
of the T-Rex in the Jurassic Park films, where some teeth overhang
and appear longer than others. Don’t sharpen them, but do make
them menacing!
The head has a connecting rod fitted between the head and the top of
the body, near the neck. Its job is to generate the head’s lift and fall
action while simultaneously opening and closing the jaws. The
connecting rod’s dimensions are 54 × 20 × 12mm. Drill a 5mm hole
all the way through the connecting rod at both ends. Locate each hole
through the centre, 6mm in from each end. Place a 4mm dowel
through the top of the body and through one end of the connecting
rod. The second peg passes through the top of the head and through
the other end of the connecting rod. Press the lower end of the head
lever in the underside and watch your beast lunge forwards and snap
its jaws as the wheels rotate.
Disassemble all the components and glass paper them, beginning
with an 80-grit glass paper followed by a 120-grit, then a 240-grit, and
finally a 1,200-grit for a super smooth surface.
Step 5: Making the wheels
1. Refer to the wheel-making process in previous chapters to guide you.
Begin making the wheels by locating the centres of both 80mm wheel
blanks. Use a ruler to connect the diagonals on both sides of the
wheel blank, then use a compass to draw a 70mm diameter circle.
Repeat to locate the centre and circumference on the other side of
2.
3.
4.
5.
6.
7.
the wheel blanks.
Drill the 9mm holes to receive the axles to a depth of 15mm on one
side of both wheels.
Turn the wheels over and mark out the location for the 2.5mm pilot
holes, 15mm from the circumference for the lower leg pivot points.
Drill to a depth of 15mm.
Remove the waste from the wheel blanks until they are completely
circular.
Cut an axle measuring 90mm in length from 9mm-diameter dowel.
Mark out and cut a 35mm-diameter eccentric cam wheel from 20mmthick timber, and locate the 9mm axle hole using a centre punch. Drill
all the way through with a 9mm drill bit. Shape the cam to a circle.
Assemble the raptor toy components, and test for ease of movement
and accuracy. It may be necessary to remove some of the cam wheel
on the circumference nearest the axle hole to allow the jaws to open
fully. Be prepared for some trial and error. Despite drawing the
components for this beast using CAD, I never quite get the same
result twice – maybe something to do with the working properties of
timber and slight human error?
Wheel and axle assembly seen from underneath. The eccentric cam will eventually be
screwed to the axle.
Step 6: Making the legs and arms
1. Cut out and assemble a pair of legs (parts J and I). Glass paper and
radius all edges prior to assembly using an M4 lock nut and 40mm
pan-head screw with two M4 washers. The screw/bolt head faces
inwards. For the final assembly, use a hacksaw to cut away the
protruding length of the bolt, and file smooth.
2. Glue the spacer blocks into place for the arms and legs. Locate their
centres and drill a 2.5mm pilot hole to a depth of 20mm into each
spacer block.
3. Dry assemble the raptor toy and attach the legs. Screw them into
place with a 10-gauge × 1¾in round-head screw at the hips, and an
8-gauge × ¾in round-head screw with an M4 washer where the lower
leg pivots against the wheel. Test the whole assembly for
smoothness and accuracy.
4. The arms can be built in two ways. One option is to make the
articulated, puppetlike arm shown here with a pivot in the wrists and
elbows. The arms are constructed from laminated, 6mm birch
plywood pieces, and pegged with 4mm dowel. Once all the pieces for
the arms have been glued, you can shape and sculpt them with a
rotary cutting tool. This method allows the arms to wave around as
the toy moves, and they look amazing if made correctly. The cutting
list for making the jointed arms is shown below. In summary, it’s an
excuse to elaborate and experiment with techniques and materials.
The diagram shows the suggested construction for a jointed arm prior to sculpting and
shaping. The right-hand bottom image is a template for a simple, one-piece construction
that can be left as a simple profile, or shaped and sculpted using a rotary shaping tool.
CUTTING LIST FOR THE JOINTED ARM
Part
Reference
Dimensions
Qty
Material
Outer upper arm
A
60 × 30 × 6mm
4
Birch plywood
Inner upper arm
B
80 × 20 × 6mm
2
Birch plywood
Inner upper arm
B
80 × 20 × 6mm
2
Birch plywood
Inner forearm
C
70 × 20 × 6mm
2
Birch plywood
Outer forearm
D
60 × 20 × 6mm
4
Birch plywood
Hand/claws
E
75 × 30 × 45mm
2
Birch plywood
35 × 4mm dowel
4
Dowel pegs
5. The second option is to make a much simpler plywood profile: this
keeps all the reptilian menace, but is more robust and easier to make.
Test fitting the arms and legs for any adjustments. The screw heads face inwards, towards
the body on the legs. They will also need to be countersunk or counter bored to a depth of
5mm to prevent rubbing against the body. The front-facing arms/claws can be allowed to
hang and pivot freely so they wave around as your dinosaur clatters along.
The claws for the raptor toy are formed from a single piece of plywood that has been
sculpted using a rotary cutting tool. You could produce a jointed/articulated claw/arm that
could flail around as your beast is wheeled along. The claws screw into the ‘shoulder’
joints at the front of the toy. They can move freely or be fixed securely.
Step 7: Painting and assembling
1. As with all the previous projects, prepare the surfaces and paint them
before assembly. The dinosaur has been sprayed with enamel paint
in several stages. The reptilian skin effect has again been created by
using fishnet stockings as a spraying mask.
2. Spray all components with two coats of grey primer/undercoat. Rub
down the primer with 240-grit glass paper.
3. Spray all the components with a dark chocolate-brown colour as a
base coat.
4. Roll on the fishnet tights and spray the upper body, upper head,
wheels, arms and upper tail with a dark green hue. Spray the
underside with a creamy yellow hue.
5. Spray the upper body and head areas with a lighter hue of green.
Give the paint several hours to dry, and roll the tights away. You
should be left with a reptilian skin pattern. Again, experiment on scrap
material first.
6. Make a card stencil or mask to spray stripes across the upper body,
the tail and the top of the head using a reddish-brown hue.
7. Use a brush to paint any smaller stripes, spots and details on the
upper arms, legs and so on. Add any other decorative features of
your own.
8. Leave the wheels the original green colour.
9. When all painting is complete, spray and seal in everything with a
clear lacquer. When dry, add some wax to surfaces in contact with
each other to act as a lubricant and reduce surface friction.
10. Glue in the handle and hand grip.
11. For the eyes, paint two 6mm wooden beads yellow, and add a black,
reptilian vertical pupil.
12. Shape the teeth from 4mm dowel, and file a taper on the ends that
point outwards. You can paint them a creamy colour. Tap them into
place with a little wood glue.
13. Use a 1,200-grit paper to rub down any stubborn, raised wood grain,
and assemble all the components for the final time.
CHAPTER ELEVEN
DEVELOPING YOUR OWN DESIGNS
Having completed the projects in this book, you are well on the way to
being able to develop your own kinetic toys. The only constant to keep in
mind is that it should be fun and rewarding. Try to keep your toy-making
as a recreational activity, but set yourself challenges to solve, both
technical and aesthetic. It can be immensely satisfying to step outside
your comfort zone, even at the risk of ruining a component or project.
New knowledge, discoveries and skills excite and invigorate the curious
craftsperson. Experiment and try out ideas before launching into a
project. Keep a journal, a scrapbook and a sketchbook to record your
development of an idea or process. Some of the most satisfying
moments are those where some large or small innovation is encountered
and consolidated. Those little moments of cognition are priceless!
It can be all too easy to play it safe and settle into mind-numbing
drudgery, especially if you are working on a commercial basis. Let the
words of the Victorian poet Robert Browning guide you:
Ah, but a man’s reach should exceed his
grasp, or what’s a heaven for?
The Value of Drawing
Many people instinctively shudder at the thought of drawing. Graphic
skills have been devalued and lost in many schools recently in the drive
for greater literacy and numeracy. To explain and explore ideas in
diagrams is perhaps the second most instinctive way we have for
communicating ideas; it’s just that somewhere, we end up feeling a
failure if we can’t draw like Raphael. Children are prolific and enthusiastic
draftspeople, but as language develops, the instinctive need to explore
ideas and feelings through drawing diminishes. Add to this the corrosive
impact of instant gratification and information technology, and it’s clear to
see why many children’s drawing skills are inhibited and stunted
technically. Good drawing is a mind playing on a flat surface. Do you
remember the joy of grabbing your pens, crayons or pencils and settling
spread-eagled on the floor to while away the afternoon sketching and
colouring furiously? You were never concerned about the work being any
good, and neither were you precious about it. You were quite happy to
work intuitively and freely.
The appeal of many folk toys lies in their immediacy and naïvety; the
apparent lack of technical mastery does not detract from their charm or
value. Don’t let your initial lack of confidence with drawing inhibit you.
Drawing is subservient to the need to explain or explore an idea, and not
a display of technical mastery. Don’t let the tail wag the dog!
Flat views are a perfect way of initially exploring ideas and developing
your confidence. A contour or outline drawing can be a perfect way of
exploring the external shape of an idea or component. Develop a daily
sketching habit, and your technical prowess will grow. In time, you will
find yourself thinking in three dimensions, and will be able to rotate an
idea in your mind like a computer-generated model.
Study your subject matter to get greater insight and inspiration. The frog toy was designed
and made after exploring frogs and toads through drawing.
There are lots of 3D drawing systems to explore to develop your
drawing skills, such as perspective, isometric projection and oblique
projection. Each has a useful quality, depending on what you are trying to
communicate or explain/explore. Drawing is not an esoteric art! The
basics can be easily acquired and developed.
Graphic materials have particular properties that make them useful for
different applications. Traditional ink drawing pens are excellent for
sketching ideas quickly, as they come with different diameter nibs and
can be enhanced with colour and tone. Try lightly drawing detail with a
HB pencil and then beefing up the detail you want to emphasize with
pens.
Walt Disney insisted that his animators spent hundreds of hours
drawing from real animals before distilling their essential characteristics
into his anthropomorphic antics. It’s worth looking at and studying your
subject matter to find inspiration and ideas.
Computer-aided design offers amazing opportunities to explore and
communicate ideas. You can also generate formal drawings such as
orthographic projection to generate production drawings to enable a third
party to build your designs.
Use drawing to explore how existing kinetic toys work. Drawing is a
fantastic way of analysing how something works, and happens in a
mental timeframe that really helps you learn and remember a particular
mechanism, process or technique. Some of the greatest innovators are
prolific sketchers. Drawing is used to explore, explain and express. Most
designing, including toy-making, is really a series of adaptations,
refinements or improvements on products that already exist.
Developing Ideas through Modelling
Samuel Colt was said to be an extremely poor draughtsman and relied
heavily on making wooden models to explain how, for example, the
chambers for his repeating revolvers could be made to rotate. The
models were then given to engineers, who planned their engineering and
production – much to the chagrin of the unfortunate victims of his
products.
Any number of materials can be used to explore ways of generating a
mechanical action, though nothing compares to card and brass paper
fasteners as a resource. Card modelling is an excellent way of
developing the geometry and dimensions for mechanisms such as
linkages, cranks and cams. The semi three-dimensional format offers an
express route to working out the shape and location of components
needed, and also helps in working out the scale and dimensions of a
design. It can be a laborious process, with many pieces ending up in the
bin until that elusive ‘eureka’ moment arrives. The card model can then
be turned into templates to be traced on to the timber. But a note of
caution: what works on a flat model does not always translate into three
dimensions.
The raptor toy began as a series of card models, where a head
attached to a class three lever is driven up and down by an eccentric cam
wheel. The initial concept did not take into account how gravity would
eventually cause the head to fail in making constant contact with the cam
wheel. The mark two version placed the lever that controls the head
motion in front of the cam wheel instead of behind. The revised card
model uses the weight of the head and the kinetic toy designer’s best
friend gravity to keep it in constant contact with the cam. The original
version explored the addition of compression springs, but the favourite
maxim by architect Ludwig Mies van der Rohe ‘less is more’ comes to
mind. The mark one raptor head and body lies languishing in a bag and
will be used as an experimental piece.
Finally, I hope you enjoy making these projects and feel enthused and
inspired to be able to begin or develop your own kinetic toy-making. I
hope you rediscover and refine your inner child, your innate playfulness
and creativity, and find a desire to share the outcomes of your efforts with
others.
Good luck.
The raptor toy was developed by making lots of card models and much experimenting with
the dimensions and location of levers, linkages and cam wheels. The final design uses
gravity to keep the head linkage mechanism in constant contact with the eccentric cam
wheel.
INDEX
articulated tail 68, 78
axle assembly 75, 86
bandsaw 13, 36, 44, 45, 55, 73, 74, 84
beech 7, 9, 30
birch plywood 11, 41, 46, 54, 53, 56, 58, 68, 70, 78, 83, 84, 86, 88
brazing rod 63, 64
cam and follower housing 43, 56
cam and follower mechanism 22
cam follower and guide block 56
canvas interface 68, 72, 73, 82
card modelling 92
centre punch 13, 25, 33, 34, 35, 39, 43, 44, 49, 56, 58, 61, 62, 70, 74, 81,
86
chain and sprocket 18
colour 25, 29, 30, 32, 39, 51, 67, 76, 77, 89, 90, 92
Colt, Samuel 92
compound angle 33, 81
connecting rod 19, 53, 60, 61, 62, 63, 64, 65, 66, 78, 84, 86
conversion process 8
correct order 12
countersink 34, 37, 46, 56, 60, 71, 84
coping saw 36
cutting across the grain 9, 13
cutting list 32, 41, 53, 62, 63, 68, 69, 78, 79, 87, 88
datum point 12
decoupaged details 67
develop your own kinetic toys 90
dowel 27, 28, 32, 39, 41, 42, 43, 48, 50, 53, 54, 56, 59, 60, 63, 67, 68,
69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 86, 87, 89
dowel pins 73, 74, 83, 84
drawing 86, 90, 92
drum sanders 12, 25, 26, 34, 35, 36, 47, 85, 72
dry assemble 36, 49, 87
dry fit 36, 39, 77, 84
dust extraction 12
eccentric cam 17, 49, 53, 54, 55, 56, 57, 58, 60, 62, 78, 79, 81, 84, 86,
92, 93
edible food dyes 31
enamel paint 29, 40, 67
epoxy adhesive 40, 52, 67
European white wood 89
experiment 31, 40, 67, 87, 89, 90, 93
Far Eastern plywood 11, 19
fishnet stockings 77, 89
fluted dowel pegs 70, 82, 83
folk toys 90
food colouring 40
Forstner bit 24, 28, 70, 81, 82
gears 17, 18
gluing 24, 25, 27, 44, 70, 76, 79
graphic materials 92
gravity 17, 21, 22, 92, 93
grey primer/undercoat 52, 77, 89, 52,
handle 19, 25, 26, 34, 39, 41, 44, 52, 55, 56, 67, 70, 77, 81, 89
inside wheel and peg mechanism 21
internal cavity 26
jig 28, 59, 65, 13
jointed arms 87
lever 15, 16,17, 26, 27, 32, 79, 81, 84, 86, 92, 93
lime wood 10
linkage mechanism 78, 84, 93, 16
lock nut 38, 42, 50, 63, 64, 66, 76, 77, 87
machine vice 13, 26, 34, 44, 55, 56, 59, 61
manufactured boards 11
MDF 32, 11
mechanism 6, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 27, 28, 78, 84, 92,
93
mix and match different mechanisms 23
oak 7, 10
offset drive axle 20
offset wheel 19, 20
oil finishes 30
opposed offset wheel and axle 20
orbital sander 13, 85
outside wheel peg and pivot 68
pack the cavity 35, 46, 56, 59
paints 29, 30, 31, 40, 41, 52, 67, 77, 89
pan head screw 50, 63, 64, 66, 76, 77, 87
parallel 28, 34, 36, 50, 63, 70, 75, 81
pawl and ratchet 18
photocopier 33, 42, 43
pillar drill 13, 25, 26, 34, 45, 70, 74, 81, 84
pilot hole 28, 35, 36, 39, 49, 50, 59, 61, 63, 64, 75, 76, 77, 86, 87
pivot point 16, 17, 27, 35, 44, 46, 47, 48, 50, 56, 61, 63, 66, 71, 75, 76,
37, 82, 86
power tools 13, 25, 12
preferred sizes 8
pulley 17, 18
radius 25, 35, 36, 37, 45, 49, 56, 58, 61, 63, 83, 87
ratio 17, 18, 24, 33, 40, 55, 69, 79
recycling 9
ripping work 13
rotary cutting tools 12, 13, 25, 26, 37, 72, 73, 86
router 11, 12, 13, 35
sapele 7, 10, 11
Scotch yoke 18, 19, 20
scroll saw 13, 37
sculpt and shape 25, 44
shellac sealer 29
spacer block 27, 49, 50, 63, 64, 78, 81, 84, 87
spray paint 29, 41
sprockets 18
stencil 24, 32, 39, 40, 52, 88
synchronized offset wheel and axle 19
surface preparation 29
surgical spirit 30, 39
tenon saw 55, 57, 61
true vertical 43, 44, 56, 70, 81
types of motion 15
varnish 29, 30, 32, 39, 40
wax 7, 29, 30, 39, 40, 51, 77, 89
wheels in contact or engaged wheels 22
wood drill bit 24
wood dye 30
wood lathe 13
wooden bead 34, 46, 51, 59, 60, 84, 89
working properties of timber 86
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