Woodworking Measuring
Instruments
Tools used for woodworking, cabinet
making, joinery, and carpentry
Tools of the trade.
Bulls Eye Level
• A bull's eye level is a type of spirit level that allows for the leveling of
planes in two dimensions - both the 'pitch' and 'roll' in nautical terms.
Standard tubular levels only consider one dimension. Bull's eye levels
are used primarily by carpenters in construction, but can also be found
as features of compasses or other devices that need to be kept from
tipping in certain directions (whether it be for functionality or
precision of measurements). Small bull's eye levels are also found
incorporated into tripods.
• Another name for a bull's eye level is a "circular bubble" which is the
name used by surveyors in the United Kingdom. Surveying instruments
such as theodolites (transits) and total stations often have a circular
bubble as well as a tubular level or "plate level". The circular bubble is
used to roughly level the instrument in two dimensions and then the
plate level, being more precise, is used to level the instrument more
precisely in each dimension separately by leveling the plate level, then
spinning the instrument 90 degrees and leveling the plate level again.
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Calipers
• A caliper is a device used to measure the distance between
two opposing sides of an object. A caliper can be as simple
as a compass with inward or outward-facing points. The
tips of the caliper are adjusted to fit across the points to be
measured, the caliper is then removed and the distance
read by measuring between the tips with a measuring tool,
such as a ruler.
• It is used in many fields such as mechanical engineering,
metalworking, woodworking, science and medicine.
• How to read a vernier caliper
Chalk Line
• A chalk line or chalk box is a tool for marking
long, straight lines on relatively flat surfaces,
much farther than is practical by hand or with
a straightedge.
• It is an important tool in construction and
carpentry, the working of timber in a rough
and unplaned state, as it does not require the
timber to have a straight or squared edge
formed onto it beforehand.
Combination Square
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Measuring angles — A combination square can reliably measure 90°
and 45° angles. The 45° angle is used commonly in creating miter joints.
Determining flatness — When working with wood the first step is to
designate a reference surface on a board which is known as the face
side. The rest of the work piece is measured from the face side with the
next surface being the face edge.
Measuring the center of a circular bar or dowel. The rule is assembled
through the center of the center square, the two cast iron legs of the
center square are then placed against the outside of the bar (dowel)
allowing a center line to be scribed alongside the ruler. Perform this
action at two locations and the intersecting lines will approximate the
center of the bar (dowel).
Protractor head allows angles to be set and measured between the
base and ruler.
A rudimentary level for approximating level surfaces is incorporated in
the protractor and also the 45° holder.
Marking the work surface; with the included Scribe Point stored in a
drilled hole in the Square Base.
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Laser line level
A laser line level is a tool combining a spirit level and/or plumb bob with a
laser to display an accurately horizontal or vertical illuminated line on a
surface the laser line level is laid against. Laser line levels are used wherever
accurate verticals and horizontals are required, typically in the construction
and cabinetry industries. Some models are inexpensive enough for do-ityourself applications.
The laser beam is fanned to produce a thin plane beam accurately
horizontal or vertical, rather than a pinpoint beam. The axis of the laser is
offset from the wall, so that a pinpoint beam would be parallel to and offset
from the wall, and would not illuminate it; the fanned beam will intersect
the wall, creating an accurately horizontal (or vertical) illuminated line along
it.
The machine is set up using the built-in spirit level or plumb bob, and the
line along the surface is then guaranteed to be accurately horizontal or
vertical to within a certain tolerance, specified either in millimeters per
meter or fractions of an inch over a specified distance in feet. A more
advanced device may be accurate to within 0.3 mm/m; while lower-end
models may be closer to 1.5 mm/m.
The illuminated line is necessarily absolutely straight, so that the line level
can be used as a straightedge; for example, to see if a shelf is warped, even
if not horizontal.
Ruler
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A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing,
printing and engineering/building to measure distances and/or to rule straight lines. Strictly
speaking, the ruler is essentially a straightedge used to rule lines, but typically the ruler also contains
calibrated lines to measure distances.[1]
Rulers have long been made of wood in a wide range of sizes. They are not however all wooden.
Plastics have been used since they were invented; they can be molded with length markings instead
of being scribed. Metal is used for more durable rulers for use in the workshop; sometimes a metal
edge is embedded into a wooden desk ruler to preserve the edge when used for straight-line cutting.
12 inches or 30 cm in length is useful for a ruler to be kept on a desk to help in drawing. Shorter
rulers are convenient for keeping in a pocket.[2] Longer rulers, e.g., 18 inches (45 cm) are necessary in
some cases. Rigid wooden or plastic yardsticks, 1 yard long and meter sticks, 1 meter long, are also
used. Classically, long measuring rods were used for larger projects, now superseded by tape
measure or laser rangefinders.
Measuring instruments similar in function to rulers are made portable by folding (carpenter's folding
rule) or retracting into a coil (metal tape measure) when not in use. When extended for use they are
straight, like a ruler. The illustrations on this page show a 2-meter carpenter's rule which folds down
to a length of 24 cm to easily fit in a pocket, and a 5-meter-long tape which retracts into a small
housing.
A flexible length measuring instrument which is not necessarily straight in use is the tailor's fabric
tape measure, a length of tape calibrated in inches and centimeters. It is used to measure around a
solid body, e.g., a person's waist measurement, as well as linear measurement, e.g., inside leg. It is
rolled up when not in use, taking up little space.
Marking gauge
• A marking gauge, also known as a scratch
gauge,[1] is used in woodworking and
metalworking to mark out lines for cutting
or other operations.[2] The purpose of the
gauge is to scribe a line parallel to a
reference edge or surface. It is used in
joinery and sheet metal operations.
• The gauge consists of a beam, a headstock,
and a scribing or marking implement,
typically a pin, knife, pen or wheel. The
headstock slides along the beam, and is
locked in place by various means: a locking
screw, cam lever, or a wedge. The marking
implement is fixed to one end of the beam.
Marking Knife
• A marking knife is a woodworking layout tool. It is
used to scribe a line to be followed by a hand saw or
chisel when making woodworking joints and other
operations.
• Marking knives have a steel blade which is sharpened
to a knife edge. The purpose of the knife edge is to
sever fibers as the marking knife is drawn over them.
This produces a very accurate line which aids in making
accurate cuts with the saw or chisel. The blade is of
tool steel with a hardwood or plastic handle.
• These instruments are generally used when laying out
across the grain. They are avoided when laying out
with the grain as the blade tends to follow the fibers,
resulting in inaccurate lines. The scratch awl is
preferred for long grain layout.
Plumb bob
A plumb-bob or a plummet is a weight, usually with a pointed tip
on the bottom, that is suspended from a string and used as a
vertical reference line, or plumb-line.
The instrument has been used since at least the time of ancient
Egypt[1] to ensure that constructions are "plumb", or vertical. It is
also used in surveying to establish the nadir with respect to
gravity of a point in space. They are used with a variety of
instruments (including levels, theodolites, and steel tapes) to set
the instrument exactly over a fixed survey marker, or to transcribe
positions onto the ground for placing a marker
Scratch Awl
• A scratch awl is a woodworking layout and
point-making tool. It is used to scribe a line to
be followed by a hand saw or chisel when
making woodworking joints and other
operations.
• The scratch awl is basically a steel spike with its
tip sharpened to a fine point. The tip of the
spike is drawn across the timber, leaving a
shallow groove. It may also be used to mark a
point by pressing the tip into the timber.
• This instrument is generally used when
dimensioning and for laying out with the grain.
It may also be used across the grain. However, a
marking knife is preferred for this operation.
Sliding Bevel
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A sliding T bevel is an adjustable
gauge for setting and transferring
angles. The handle is usually
made of wood or plastic and is
connected to a metal blade with
a thumbscrew or wing nut. The
blade pivots and can be locked at
any angle by loosening or
tightening the thumbscrew.
In use
The bevel can be used to
duplicate an existing angle, or set
to a desired angle by using it with
any number of other measuring
tools (such as a protractor,
Combination square, or framing
square).[1]
How to use a sliding bevel link.
Speed Square
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A speed square or rafter angle square is a triangular-shaped measuring
tool used to draw straight lines on lumber to be cut, or to lay out angles
for roofs, stairways, decks and other general construction. The tool is
marked with degree gradations for fast layout and cutting of lumber
without performing complex trigonometry calculations. It was invented
in 1925 by Albert J. Swanson. He called it the "Speed Square," since it
provides a short cut for measurements and calculations of angles.
Speed Square is a registered trademark of the Swanson Tool Co., Inc.,
which continues to sell it under that name, though the name itself has
become a generalized trademark for all rafter angle squares. Modern
Swanson squares can be differentiated from other manufacturer's rafter
angle squares by their SPEED trademark and their trademarked diamond
shape cutout at the 3½ inch mark, which assists in making birds mouth
cuts.
Generally, the tool comes in two sizes - the compact 7 inch version for
portable use and the larger less portable 12 inch version for stationary
work. They may be made of aluminum, steel, HDPE, and other composite
materials.
A version of the 7 inch square is made by Stanley tools under their name
"Pocket Square"
Spirit Level
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A spirit level or bubble level is an instrument designed to indicate whether a surface is
horizontal (level) or vertical (plumb). Different types of spirit levels may be used by
carpenters, stonemasons, bricklayers, other building trades workers, surveyors,
millwrights and other metalworkers, and in some photographic or videographic work.
Original spirit levels had two banana-shaped curved glass vials at each viewing point
and were much more complicated to use. In the 1920s, Henry Ziemann invented the
modern level with a single vial. These vials, common on most ordinary levels today,
feature a slightly curved glass tube which is incompletely filled with a liquid, usually a
colored spirit or alcohol, leaving a bubble in the tube. At slight inclinations the bubble
will travel away from the center position, which is usually marked in some manner.
Alcohols such as ethanol are often used rather than water for a variety of reasons.
Alcohols generally have very low viscosity and surface tension, which allows the bubble
to travel the tube quickly and settle accurately with minimal interference with the glass
surface. Alcohols also have a much wider liquid temperature range, and won't break
the vial as water could due to ice expansion.
Some spirit levels are capable of indicating the level of a surface between horizontal
and vertical to the nearest degree. An extension of the spirit level is the bull's eye level:
a circular, flat-bottomed device with the liquid under a slightly convex glass face which
indicates the center clearly. It serves to level a surface across a plane, while the tubular
level only does so in the direction of the tube. The most sophisticated spirit levels are
guaranteed accurate to five-ten-thousandths (.0005) of an horizontal inch at the center
per vertical inch at either end. Where a spirit level must also be usable upside-down,
the banana-shaped tube is replaced by a barrel-shaped tube. The upper internal
surface of the tube is thus always of an appropriate shape.
Steel Square
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The steel square is a tool that carpenters use. They use
many tools to lay out a "square" or right-angle, many of
which are made of steel, but the title steel square refers to a
specific long-armed square that has additional uses for
measurement, especially of angles, as well as simple rightangles. Today the steel square is more commonly referred to
as the framing square. It consists of a long arm and a shorter
one, which meet at an angle of 90 degrees (a right angle). It
can also be made of metals like aluminum, which is light and
resistant to rust.
The wider arm, two inches wide, is called the blade; the
narrower arm, one and a half inches wide, the tongue. The
square has many uses, including laying out common rafters,
hip rafters and stairs. It has a diagonal scale, board foot scale
and an octagonal scale. On the newer framing squares there
are degree conversions for different pitches and fractional
equivalents.
Carpenter's squares are very much like steel squares.
Storey Pole
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A storey pole (or story pole) is a length of narrow board,
often a 1x4 usually cut to the height of one storey. It was used
as a layout tool for both wood framing and brickwork,
measured and marked by the master carpenter for the
heights from (usually) the floor platform of a building for
dimensions such as window sill heights, window top heights
(or headers), exterior door heights (or headers), interior door
heights, wall gas jet heights and the level of the next storey
joists. It made for quick, repeatable measurements without
the need of otherwise calibrated measuring devices or
workers skilled in using them.
How to create a storey pole for use in construction.
Straight Edge
• A straightedge is a tool with an edge free from
curves, or straight, used for transcribing straight
lines, or checking the straightness of lines. If it
has equally spaced markings along its length it
is usually called a ruler.
• Straightedges are used in the automotive
service and machining industry to check the
flatness of machined mating surfaces.
• True straightness can in some cases be checked
by using a laser line level as an optical
straightedge: it can illuminate an accurately
straight line on a flat surface such as the edge
of a plank or shelf.
Tape Measure
• A tape measure or measuring tape is a
flexible form of ruler. It consists of a
ribbon of cloth, plastic, fiber glass, or
metal strip with linear-measurement
markings. It is a common measuring
tool. Its flexibility allows for a measure
of great length to be easily carried in
pocket or toolkit and permits one to
measure around curves or corners.
• In our shop, we aim for a 1/16”
accuracy on all jobs. Can you read a
1/16 of an inch? If not, check out this
link. Remember to return and finish
this assignment.
• Ruler Game
Try Square
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A try square or try square is a woodworking or a metal
working tool used for marking and measuring a piece of
wood. The square refers to the tool's primary use of
measuring the accuracy of a right angle (90 degrees); to try
a surface is to check its straightness or correspondence to
an adjoining surface. A piece of wood that is rectangular,
flat, and has all edges (faces, sides, and ends) 90 degrees is
called four square. A board is often milled four square in
preparation for using it in building furniture.
A traditional try square has a broad blade made of steel
that is riveted to a wooden handle or 'stock'. The inside of
the wooden stock usually has a brass strip fixed to it to
reduce wear. Some blades also have graduations for
measurement. Modern try squares may be all-metal, with
stocks that are either die-cast or extruded.
'Try square' is sometimes incorrectly spelled 'tri square'. Its
etymology though is from 'trying', in the sense of testing,
rather than the prefix 'tri-' meaning three.
Winding Sticks
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Winding sticks are used in woodworking to help in
flattening boards, usually when the task is undertaken
with a hand plane.
Winding sticks are basically two short lengths of timber
or some other flat and stable material. Any pieces of
timber of a suitable size and straightness may be used,
although many woodworkers will make one or more
matching pairs for the purpose. Contrasting woods are
often used to improve the ability to discern differences
in height and level between the two sticks.
The sticks are used in pairs, with one stick placed flat
and perpendicular to the length of the board at each
end. The woodworker then sights across the top of the
two sticks. If the surface on which the sticks are sitting is
flat, the edges of the two sticks will line up perfectly
with each other, if not, the discrepancy will indicate any
warping or high spots that may exist. The process is
often repeated by moving the sticks to different
positions along the length of the board to check the full
length of the board.
Adjustments to the surface of the board are made with
a hand plane or other method of wood removal and the
process described above is repeated until the board is
satisfactorily flat.
Compass
• A compass has a pivot at the top and two legs,
one with a pointed end and one with a pencil
tip. This tool is used to scribe and transfer
radius arcs, circles, and patterns during the
layout process.
Dividers
• Definition of Dividers:
Dividers are tools used
for transferring
measurements and
laying out circles and
arcs. Dividers are
similar to a compass
but often have two
metal points rather the
a pencil and one point.
Protractor
• A woodworker’s protractor is a simple
tool used to determine angles. It has a
head with a flat base, upon which a
pivoting blade is attached. The blade is
aligned with the angle, which is then
indicated in degrees on a graduated
scale etched into the head. How to use
this tool link.
• Video lesson
Center Gauge
• Center gauges are used to locate the center of
a round object or to locate the center on a
rod.
• Larger objects require using a straight edge,
and is really quite simple to do. Check out this
link. Finding the center on an 18” circle.
This slide show has walked you through the basic measuring tools of the trade and is
by no means the end of the available tools available. You are responsible to know the
names and understand the proper use of each tool. Take some time to go back and
review each tool, check out the links and learn how to use these tool.
• Review Quiz Friday, March 23.