What is linear measurement?
• A system for measuring length
• Measuring devices, also called layout tools, are used
to measure length.
• Examples of tools used: rules, squares, scratch
awls, calipers,
measuring tapes
and dividers
Photo courtesy of Snap-on Tools.
Purpose of linear measurements:
• Measure and mark materials before cutting or
shaping
• Construct a project from a pattern
• Create your own pattern
• Lay out a project
Materials for measuring devices …
• Steel
– Durable – lines and numbers stay visible for a long
time
– Bends without breaking
– Withstands rough use
– First choice of material for calipers, dividers and
other slender tools that must measure very
accurately and not bend easily
Materials for measuring devices
(cont.) …
• Aluminum
– 2nd choice for many layout tools
– Tough, lightweight and durable
• Wood
– Cheap, soft and lightweight
– Breaks easily, absorbs moisture
– Does not wear well
– Popular for the wooden folding rule
Materials for measuring devices
(cont.) …
• Plastic
– Tough and lightweight
– Melts if touches hot object or flame
– May be damaged by solvents
– Limited use
• Cloth
– Used for some 50-foot tapes
– Cheap and lightweight
– Not very accurate – stretches under stress
Cost vs. quality …
• Cheap tools are seldom a bargain.
• Cheap tools are likely to be inaccurate and
unsatisfactory after very little use.
• Good tools may seem expensive, but last a
lifetime with proper use.
• Good tools allow skilled labor and craft.
• Even a skilled worker cannot do good work
with poor tools.
English/U.S. customary system of
measurements …
• Uses inch, foot, yard, rod and mile
• INCH – traditional U.S. unit for
woodworking and metalworking
Metric system of measurement …
• Used for scientific work in the U.S.
• Increasingly used for nonscientific use.
• Many layout tools use both metric and U.S.
customary markings.
• Based on multiples of ten
• Easy to use without fractions
Common tools for linear measurements:
• Tapes, rules and scales
• Last number on the scale is read plus any
fraction
Measuring tape:
•
•
•
•
Flexible measuring device that rolls into a case.
Several feet to hundreds of feet
Steel, cloth or fiber
Often self-retracting with
locks or buttons
• Usually has end hook
• Easily broken – handle
Photo courtesy of Snap-on Tools.
with care
Folding rule:
•
•
•
•
•
•
Rigid rule
2-8 feet in length
Foldable for easy handling and storage
Insert for easy inside measurements
Wood, plastic or metal
Take care when
opening and closing
Scale:
• In this use, refers to rigid steel or metal
measuring device
• 1-3 feet in length, ¾ to 1” in width
• Wooden scales sometimes called bench
rules – about ¼” thick
• Metal scales are relatively thin, accurate
• Handy in the shop, not used much
otherwise
Why use squares, levels and lines?
• Measuring angles and cutting accurately are
essential for the success of any construction
project.
• Squares, levels and lines are all tools that are
used to guide the builder, where a particular
angle or a level measurement is needed.
Essential measuring and cutting
tools:
• Squares – draw angles for cutting and check
cuts for accuracy
• Levels – determine if an object has the same
height at two or more points
• Line – thin material stretched tightly between
two or more points
More about squares:
• Used to draw angles for cutting and to check
the cuts for accuracy
• Most commonly used squares:
– Framing square
– Try square
– Combination square
– Sliding T bevel, also called a bevel square
The framing square:
16” wide
24” long
• Flat square with a body and tongue
• Usually made of steel
• Also called a carpenter's square
and a steel square
• May contain tables to calculate
board feet and rafters
• Has both inside and outside
measurements
The try square:
• Used to try or test accuracy of cuts
• Used to mark lines on boards before cutting
• Steel blades with wood, steel or plastic
handles
• Good for marking boards
up to 12”
• Used to draw 90 or 45°
lines on boards
•
•
•
•
•
•
•
Combination square:
Combines many tools
Bubble for leveling
Bubble for plumbing
Depth gauge
Removable blade for steel scale
Use for square and for 45° angle
Most commonly used square
Sliding T bevel
• Device to lay out angles
• Also called bevel square
• A bevel is a sloping edge as when
a corner edge is cut away from a
board
Using a spirit level:
• Determine if an object has the same
height at two or more points
– Contains alcohol in a sealed, curved tube
with a small air space or bubble
– Mounting is wood or aluminum
– Bubble between 2 lines
when both ends are
even
– Crossways mounted
tube can be used to
plumb an object
Using a line level:
• Attached to a string or line stretched between two
distant points
• When the string is pulled tight, the level indicates
when both ends are the same height.
• Useful for leveling the corners when building with
block and for setting stakes to gauge the depth
of concrete.
Laser beam level:
• Directs a strong beam of light across a space
• Level mark can be made at several points and
at varying distances
• Useful in laying out houses and other buildings
Using lines:
• Strong cotton or nylon line
• For block, flooring, cutting rafters, ceiling tiles,
etc.
• Chalk line – cord with chalk leaves trail
• Plumb line – string with round and pointed
metal plumb bob attached which hangs in
perfect vertical line
Using a square to mark a board:
1.
2.
3.
4.
Measure and mark the desired length.
Place handle firmly against board edge.
Move the blade against the mark.
Draw a line across the board.
Squaring a large area:
• Even 1° error can cause serious problems on
large construction job
• Measure 90° angle by creating a right triangle
with sides that are 3’, 4’ and 5’.
• Determine if a rectangle is square by
measuring the diagonals. Both must be equal.
Parts of a portable electric drill:
• A portable power drill is a small tool run by
an electric motor that can be easily moved to
the work.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Power cord
Handle
Motor housing
Gear chuck
Vents
Trigger switch
Trigger switch lock
Reversing switch
Chuck key or wrench
Classifying drills:
1. Chuck Size (the device that holds a drill or tool bit in
the machine): commonly 1/4”, 3/8”, 1/2”
2. Power Rating: typically from 2 to 5 amperes. A 115volt motor using 5 amperes equals about ½
horsepower and is considered powerful for a
portable drill.
3. Duty Cycle: the amount of time a motor can run
versus the time it needs to cool off. Continuous duty
drills can be used all the time for 6-8 hrs.
Types of drills:
• Variable Speed: motor
speed can be controlled
by the operator
• Reversible Drills: can
run backward and
forward
Photo courtesy Snap-on Tools.
Types of drills:
• Hammer Drills: will
turn a bit and also
provide rapid striking
action useful for
masonry materials
• Cordless Drills: contain
a rechargeable battery
pack
Photos courtesy
Snap-on Tools.
Uses for drills:
•
•
•
•
•
Drilling holes
Turning screws in and out
Drilling holes in brick, block or stone
Making holes
Sanding and polishing
Recommended procedures:
1. Use only straight shank bits.
2. When tightening a drill chuck, place the key into the
hole and tighten the chuck securely. Place the key
into a second hole and, again, tighten securely.
3. Center punch metal to help start a drill bit.
4. Always make sure the drill bit is sharp.
5. Hold materials to be drilled in a vise or other secure
device.
6. Use slow-turning drills for large bits.
Recommended procedures:
7.
8.
Use even pressure on the drill.
Ease off the pressure when the drill is breaking
through the material.
9. Hold the drill so as to avoid binding the drill bit.
10. Position yourself so that balance is always
maintained; never lean on a drill.
11. Remove the drill bit from the chuck when finished.
12. Store the portable power drill in its own case or in
a special storage rack.
Pilot holes:
• For large holes, a pilot hole is used – a small hole
drilled in material to guide the center point of larger
drills.
• Pilot holes are also used when installing screws to
prevent splitting the wood.
• If a drill bit is not cutting, check to see if the reverse
switch is on. If the drill is turning clockwise and not
cutting, the drill bit is dull and must be sharpened.
Ag Engineering Library
So what’s the big deal about hand
tools?
•
•
•
•
•
•
Have been around for centuries
Can create very high quality projects
Require more skill than power tools
Generally safer than power tools
Safety procedures required
High quality hand tools may be more
expensive than power tools.
Advantages to hand tools:
• Can be used without electricity
• Sometimes more appropriate than power
tools
• No set-up needed
Classifying hand tools:
• No power required – use simple machine
principles like inclined planes, wheel and
axle, levels and fulcrums
• May be named for user (carpenter, mason,
machinist, mechanic)
• Use or function (layout, cutting, boring,
driving, holding, turning)
Layout tools:
• Measure or mark wood, metal and other materials before
cutting or shaping
• Examples: rulers, squares, scratch awls, gauges, calipers,
measuring tapes and dividers
• Ensure correct length, width, thickness and/or shape
• An example of hand tools that are not generally replaced
by power tools
Layout tools – examples:
Photos courtesy of Snap-on Tools.
Cutting tools:
• Chop, cut, saw or
otherwise remove
material
• Permit user to shape
material
• Examples: saws, chisels, hatchets and knives
• Sharp edge must be kept keen.
• Cutting edges are usually made of high carbon
steel, tungsten or carbide.
Photo courtesy of Snap-on Tools.
Handsaws:
• Cut across boards or rip boards and panels
• Crosscut means to cut across the grain; Rip
means to cut along the length of the board or
with the grain.
• Teeth determine use.
– Filed to a point = cut across the grain of boards
(crosscut saws)
– Filed to a knifelike edge = cut with the grain
(ripsaws)
More details on handsaws:
•
•
•
•
•
Length from 20 to 28 inches
Shorter saws for smaller people
Shorter saws for finer cuts use finer teeth
Teeth range from 6 to 14/inch
Backsaw is mounted in box or frame to cut
precise angles
• Coping saw used to cut curves in wood
Handsaw details:
Boring tools:
• Make, size or shape holes
• Examples: drills, bits, reams
and the devices used to turn
them
• Sharp cutting edge must be
maintained
• Variety of shapes, sizes and
types
Driving tools:
• Used to move another tool or object such as a nail, a
punch or a chisel
• Examples: mallets, hammers and sledges.
• Size and type depend on intended use
• Claw hammers – 2 types (curved and ripping) – are used
to pry wood apart and to extract nails.
• Rubber and plastic mallets are used for moving wood and
other materials without marring the surface.
Hammers and mallets:
Holding tools:
• Used to grip wood, metal or plastic
• Used as an aid while other tools are used to
cut, shape, modify or fasten the material
being held
• Examples: clamps, pliers and vises
Holding tools – examples:
Photos courtesy of Snap-on Tools.
Turning tools:
•
•
•
•
•
Used to turn nuts, bolts or screws
Examples: wrenches, sockets and drivers, and screwdrivers
Often used to install a fastener in wood or other material
Variety of types and sizes
Size depends on the amount of torque (twisting power)
needed. Those with longer handles or longer in reach
usually provide more torque. This uses the principle of a
lever.
Turning tools – examples:
Photos courtesy of Snap-on Tools.
Rust is a big problem!
• A chemical reaction when moisture meets
metals containing iron
• Rust is also called ferric oxide.
• Rust is corrosive – eats away metals containing
iron
Problems caused by rust …
• Can destroy tools
• Prevents efficient tool use
• Parts like bolts can “freeze” together so they
must be cut off.
Possible solutions for rust problems
…
• Dissolve rust with penetrating oil
• Apply heat from a torch to loosen rusty parts
• Cut off rusty bolt with a cold chisel
Watch out for rust on …
• Stationary tools
– Table saws
– Planers
– Joiners
– Shapers
– Band saws
• Cast iron beds can stain
and mark wood and will not slide easily.
It’s a matter of degree …
• Light surface rust
– Reddish brown to black specks
– If left unattended will become serious
– Best stage for rust removal
• Advancing rust
– Large red or brown surface spots
– Progression of light surface rust
Getting more serious …
• Complete rust
– Solid reddish brown over entire surface
– Serious damage
• Scaly rust
– Completely covers surface
– Comes off in scales if rubbed
– Pitted surface and serious damage has advanced
Now you’re really in trouble …
• Complete rust-through
– Holes appear in the metal
– Almost beyond repair
Removing rust …
• Light rust – use fine steel wool dipped in light
oil
• Pitted surface – wire brush, , wire wheel, steel
wool, emery cloth or aluminum oxide paper
NOTE: Pitting is a sign of permanent damage
and should be avoided!
Getting rid of rust …
• Use a wire brush for tools like shovels
– Apply the wire brush to the surface.
– Brush off the loosened rust.
– Continue until all rust is removed.
• Use a wire wheel for tools and bolts
– Mount on stationary power grinder
• Use a wire wheel for larger
surfaces
– Mount on portable grinder
Finishing off the rust removal:
• Use 400-grit silicon carbide paper.
• Add light oil to the paper for a very smooth
surface.
• Dry metal thoroughly.
• Coat all smooth metal surfaces
with light oil.
• Use heavier oil for rougher surface.
Don’t leave oil on some surfaces …
• Beds of stationary power woodworking tools
– Oil will contaminate wood.
– Use a high-quality paste wax on the surface
instead.
Steps to treating a stationary power
tool bed:
1.
2.
3.
4.
5.
6.
7.
Clean machine bed of all rust.
Use fine steel wool or 400-grit paper.
Wipe away loosened rust.
Apply wax in circular motion.
Allow wax to dry to a haze.
Buff wax with soft cloth.
Apply a new coat after each use.
Protecting surfaces …
• Prevent moisture from contacting iron by
using a coating of oil or wax.
• Protecting tools
– Keep in a dry place
– Coat with oil or wax
– Enclosed building for storage, not open shed
• Primers and paints
– Remove rust, then prime and paint
Wooden handles are found on
common tools:
•
•
•
•
Axes
Hoes
Shovels
Posthole
diggers
• Hammers
• Picks
Pros and cons of wood:
Advantages:
• Comfortable
• Absorbs shock well
• Lightweight
Disadvantages:
• Can decay
• Can break
Wooden handles can be replaced!
How wooden handles are attached
…
• Held in place with a wedge
• Hole in head of the tool is called the eye
• Eye is smaller on the side where the handle
enters than on the opposite side
• Once inserted, the handle can be wedged to
fill the hole
• Improper fit is ineffective and dangerous
Removing a broken handle:
1. Place the head securely in a vise.
2. Use 1/4” or 3/8” metal cutting bit to drill
numerous holes in the wooden core.
3. Drive the remaining wood out of the head
using a large punch.
Replacement handles for hammers
and axes:
• Buy the correct size.
• The end of the handle that goes into the eye of the
tool should be longer than the eye is deep and have
the same shape as the eye.
• It should also be slightly larger in cross section than
the eye.
• Make the handle fit exactly by placing it in a vise and
shaping the end of the handle that is to be inserted
into the eye.
Attaching a hammer or axe handle:
1. Place the head against the end of the handle
to see if it will start on.
2. Observe where wood must be removed to
shape the handle to enter the head.
3. Use a wood rasp or coarse file to shape the
handle.
4. Try the head frequently as wood is removed
to avoid a loose fit.
Attaching a hammer or axe handle
(cont.):
5. Work the handle down until the head slides on
snugly. It should come to rest about 1/2" from the
enlarged part of the handle.
6. Mark the handle on both sides of the head.
7. Remove the head.
8. Reposition the handle vertically in the vise. Place
the head against the end of the handle to see if it
will start on.
Attaching a hammer or axe handle
(cont.):
9. Use a handsaw to make a
kerf across the longest
center line of the handle.
The kerf should extend
two-thirds of the distance
between the two marks
in step 6.
10. Reposition the handle in the vise and squeeze the
end until the saw kerf is completely closed.
11. Run the saw down through the kerf again. When
released, the kerf will be wider at the end than
farther down the handle.
Attaching a hammer or axe handle
(cont.):
12. Make a wooden wedge as wide as the oval
hole in the head and thick enough to spread
the handle when driven in.
13. Slide the handle in and drive it in
securely with a plastic, leather, rubber or
wooden mallet. (Steel hammers can ruin
wooden handles.)
14. Grip the handle with the vise just
below the head.
Attaching a hammer or axe handle
(cont.):
15. Use a hacksaw to saw off the excess
handle flush with the head.
16. Drive the wooden wedge so the
handle spreads and fills the head.
17. Use a hacksaw to saw off the excess
wooden wedge.
18. Drive one or two metal wedges in at
right angles to the wooden wedge to
hold the wedge in place.
Attaching a hammer or axe handle
(cont.):
19. Place the tool, head down, into a metal or plastic
container about the size of the head.
20. Add several inches of boiled linseed oil and brush
oil around the handle and head.
21. The handle and head should soak in the oil several
days to seal the wood.
22. Remove the tool, rub oil on all parts of the handle,
dry and polish.
Attaching handles to rakes, hoes
and forks …
• Rakes, hoes and forks are driven
into their handles.
• The handles have metal collars
called ferrules.
• The tool has a metal finger
called a tang which is
driven into the ferrule.
Attaching handles to shovels:
• A metal tube
extends up the
handle for extra
support.
• Handles are made
to fit specific
shovels.
How to attach a shovel handle:
1. Grind off the head of the rivet that holds the
handle.
2. Remove the rivet with a drift punch.
3. Spread the metal tube and drive out the
remains of the old handle.
4. Use a mallet to drive the new handle
securely into place.
How to attach a shovel handle
(cont.):
5. Use a vise to close the metal around the
handle and secure the assembly while
drilling.
6. Insert a drill through the hole in the metal
and drill through the wooden handle.
7. Install the replacement rivet securely, being
careful to keep the metal tight to the wood.
Ag Engineering Library
Types of portable sanders:
• Belt sander – used for coarse sanding
• Disc sander – used for coarse sanding
• Finishing sander – used for final sanding
before finish is applied
• Power sanders serve the same functions as
hand sanding, but are much faster.
• Power sanding can create a smooth finish
on wood or metal if done correctly.
Effective sanding …
• Sanding with the grain for fine work
• Crossgrain sanding for uneven boards, very rough
boards or to remove difficult finishes
• Starts with coarse sandpaper, then medium and
ends with fine
• Belt or disc sander can be used for rapid work
followed by a finishing sander or hand sanding.
More about finishing sanders:
• They move randomly, so sanding can be done
with the grain or across the grain.
• Almost all finishing
sanders are orbital
sanders, moving in
a random circular
pattern that results
in a faster cut, but
gives a fine finish.
Photo courtesy Snap-on Tools.
Main parts of a belt sander:
• The belt sander has a moving sanding belt.
1. Motor housing
2. Handles
3. Belt
4. Belt rollers
5. Belt adjustment
6. Trigger switch
7. Switch lock
8. Power cord
9. Dust bag
Safely operating a belt sander:
1. Wear suitable face protection and protective
clothing.
2. Check the power cord and extension cords for
safety.
3. Install a sanding belt of suitable coarseness.
4. Lay the sander on its side when not in use.
5. Be sure the dust bag is empty or nearly so before
starting to sand.
6. Make sure the wood to be sanded is secured on
the table.
Safely operating a belt sander:
7.Always start the machine while holding it slightly above
the material.
8.Keep the power cord out of the way of the belt.
9.After turning on the sander, touch the work with the
front part of the belt first, then slowly settle the rest of
the belt down onto the work.
10.Operate the machine with two hands at all times.
Safely operating a belt sander:
7.Sand with the grain. Move the machine from one
end of the board to the other in a straight path;
then move it slightly sideways and draw the
machine back over the new area. Gradually work
across the board by slightly overlapping the forward
and backward passes.
8.Keep the machine in motion, letting the weight of
the sander do the work without applying pressure.
9.The final movement is to lift the machine off the
work while it is still running.
Safely operating a belt sander:
10. Examine the work carefully. Resand if necessary
to create a smooth, perfectly level surface.
11. Install a fine sanding belt and resand. This
resanding leaves the work in its smoothest
possible form using a belt sander.
12. Use a finishing sander or hand sander to obtain
the degree of fineness desired.
Parts of portable disc
sanders/grinders:
• Some tools are designed to be used as either sanders or
grinders by simply changing out the sanding disc or
grinding wheel.
1. Motor housing
2. Handles
3. Power cord
4. Switch or trigger
5. Switch lock
6. Cooling vents
7. Wheel
8. Spindle
9. Safety guard
10. Tool rest
More on sanders and grinders:
Disc sanders:
• Use grit on a flexible
revolving plate
• Aluminum oxide discs
may be used for sanding
wood or metal.
• Discs made from flint
paper are only suitable
for wood sanding.
•
•
•
•
Grinders:
Use rigid grinding
wheels
Only used for metal
Used to shape metal,
grind down welds, and
remove metal as
needed
Wire brushes may also
be turned by grinders to
clean metal.
Examples of sanders and grinders:
Disc sander:
Photos courtesy Snap-on Tools.
Grinder:
Safety precautions when using a
grinder:
• Wear a face shield.
• Check the grinding wheel for cracks or damage and
do not use a damaged wheel.
• Use wheels that are designed for the machine.
• Tighten the wheel securely and carefully.
• Never use a grinding wheel that is less than onehalf its original diameter.
• Secure small pieces in a vise, if possible.
Safety precautions when using a
grinder (cont.):
• Do not grind metal in areas with combustible gases
or materials.
• Hold the machine with both hands at all times.
• Do not discharge sparks against persons, clothing,
or other combustible materials.
Sander or grinder procedures:
1.Select the correct sanding disc, grinding wheel or wire
brush.
2.Install the appropriate guard.
3.Wear appropriate face protection and protective
clothing.
4.Be sure the work is properly secured.
5.Keep power cord out of the way.
6.Grip the machine firmly with both hands and turn on
the switch.
7.Settle the turning sanding disc, grinding wheel, or wire
brush onto the work slowly.
Sander or grinder procedures
(continued):
8. Touch the work gently with the wheel to avoid the
wheel catching the work and throwing metal
particles.
9. Do not apply pressure to the machine.
10.After turning the switch off, do not lay the
machine down until it has completely stopped.
11.Do not lay the machine down on its disc or wheel.
12.Remove the grinding wheel or sanding disc and
store the machine properly after use.
Parts of a finishing sander:
1. Motor housing
2. Handles
3. Switch
4. Switch lock
5. Power cord
6. Paper clamps
7. Pad
8. Sandpaper
Procedures for using a finishing
sander …
1.Use appropriate face and body protection.
2.Check sander to determine if it is a straight line or
orbital type.
3.With rough work, use coarse sandpaper first, then
medium, then fine sandpaper.
4.Use precut paper or cut to fit the machine.
5.Install sandpaper.
6.Apply only slight pressure and keep it in constant
motion.
7.Remove dust frequently
8.Store the machine properly when finished.
Describe
and Select
Fasteners
A fastener is …
• Any device used to hold 2 or more pieces of
material together in place
• Common agricultural mechanics fasteners:
– Nails
– Screws
– Bolts with nuts or washers
– Machine screws
•
•
•
•
•
What is a nail?
A fastener driven into the material it holds
Long stem part = shank
Enlarged top = head
Classified by use or form
Varies in shank thickness and head diameter
according to use
– Soft material needs a large head
– Heavy material needs a thick, strong shank
Nails and hammers – meant for
each other …
• Nails are driven in by a hammer.
• Small nails can be pulled out by the claws of a
hammer.
• Larger nails must be removed with a crowbar
or nail puller.
• Long nails may need a block under the puller
to provide a fulcrum.
Common nails/uses:
• Staple – wire fence construction
• Hinge – fasten hinges on doors and cabinets
• Plasterboard – attach plasterboard to studs Roofing –
nail rolled roofing and shingles
• Lead head – nail galvanized steel roofing/siding
• Cut – nail tongue-and-groove flooring
• Finishing – interior finish work, cabinets
• Box – light construction, siding, end grain of boards
• Common – general construction, sheeting
• Duplex – concrete forms, insulators
Types of nails:
Measuring nail length …
• Lengths of common nails is by the “penny,”
and symbol “d.”
• Some common sizes:
– Box nails: from 2d to 40d
– Finishing nails: from 2d to 20d
– Cut nails: from 2d to 20d
– Spikes: from 12d to 12 inches
Improved nails are modified for a
specific job …
• Soft insulating boards need nails with large
square heads
• Thread nails – part is threaded for more
holding power
• Heat treated – for hard substances
• Zinc treated – to prevent moisture
• Aluminum – for nailing aluminum
Improved nails:
What is a screw?
• A fastener with threads that bite into the
material it fastens
• Used in wood, metal, plastic
• Pilot hole is predrilled
• Screws generally cut into the material as they
are turned.
Common kinds of screws:
• Wood – threads cut into wood fibers
• Sheet metal – wider threads
• Cap screws – thread into thick metal with
matching threads
• Lag screws – very coarse threads for structural
timbers
• Drywall – thin shank and tough steel
• Deck – long screws for outside decks
Kinds of metal used …
• Steel screws may be coated with a blued,
galvanized, cadmium, nickel, chromium or
brass finish.
• Solid brass screws are rustproof and used
where severe moisture problems destroy
coated or plated screws.
Screws are classified by type of
head …
• Flat head: tapered heads fit flush with surface
• Round and oval head: rounded heads with slot
• Pan head: upside-down frying pan look/used for
sheet metal
• Lag screws: unslotted square (4 sides)
or hex (6 sides) heads and turned with wrench
Tools used to turn screws:
• Standard screwdriver – used for slotted head
screws
• Phillips screwdriver – shaped like a plus sign
• Six-sided, hex or Allen wrench – used to turn
Allen screws
• Power drill or power driver – screws with staror square-shaped holes
•
•
•
•
Measuring screw sizes:
Specified by diameter and length of shank
Diameter – from 2 through 24
Diameters 6, 8 and 10 are common
Common lengths – from ¼” to 4”
What is a bolt?
• A fastener with a threaded nut
• Common bolts used in ag mechanics: machine bolts,
carriage bolts, stove bolts, plow bolts, and special
bolts
• Threads in two types – coarse (UNC) and fine (UNF)
• Standard and metric sizes
• Most automotive engine bolts are fine threaded.
• Carriage bolt is used with wood; has a round head
over square shoulders
Types of bolts:
What is a nut?
•
•
•
•
A device with a threaded hole
Movable parts of bolts
Square (4 sides) or hex (6 sides)
Wing nuts have extensions
for tightening
• Special nuts with slots
allow cotter pins
• Graded by strength
What is a washer?
• Flat device with a hole
in the center
• Used as part of a fastener
• Flat washers prevent bolt
heads or nuts from
penetrating material.
• Special lock washers
prevent nuts or bolts
from loosening due to vibration and use.
Develop and Follow Plans:
Pressure Treated Lumber
Why treat lumber?
• Outdoor conditions can harm wood.
– Sunshine
– Moisture
• Bacteria and other organisms attack wood and
decay sets in.
• Untreated pine touching moist ground may only
last 1-2 years.
Pressure-treated lumber:
• Chemicals are driven
into the wood under
pressure.
• Chemicals prevent
wood decay and
insect damage.
How the process works:
• Lumber is immersed in preservative.
• Treated lumber is pressurized.
• Pressure forces the preservative to penetrate the
lumber.
•
•
•
•
•
Most common chemicals used as
wood preservatives:
Creosote
Pentachlorophenol
Acid Copper Chromate (ACC)
Ammoniacal Copper Arsenate (ACA)
Chromated Copper Arsenate (CCA)
CCA is #1 chemical used …
• CCA is Chromated Copper Arsenate
• Binds to wood fibers
• CCA-treated wood lasts for decades even if
wood is in contact with moisture, bacteria and
organisms in the ground.
CAUTION!!
• These chemicals are
harmful or toxic to
plants and animals
• Be careful when choosing
pressure-treated lumber
for agricultural settings.
Choose the correct pressure-treated
lumber for the job …
Ground use
• Can contact the ground
and is decay-resistant
Above Ground Use
• Should not contact the
ground
The American Wood Preservers
Bureau label includes:
1. Year of chemical treatment
2. The preservatives used in treating the lumber
3. Trademark of bureau supervising the treatment
plant
4. Proper exposure conditions
5. Treating company's location
6. Dry or KDAT if applicable
Safety observations …
• Wear gloves when handling pressure-treated
lumber.
– Chemicals are toxic.
– Splinters can penetrate the skin of your hand.
• Avoid breathing sawdust.
• Do not burn pressure-treated lumber – puts
toxic chemicals into the air.
Selecting and
Using Abrasives
What is the purpose of abrasives in
woodworking?
• To prepare wood for finishing with stains and
clear coatings
– Wood must be very smooth to accept a quality
finish.
– Usually called sanding, although true sand is no
longer used
• To remove fine marks from planning or milling
– Remove imperfections
– Remove saw marks
3 types of abrasives used in finishing
wood:
1. Abrasive
paper
2. Steel wool
3. Rubbing
compounds
Getting down to the nitty gritty:
• Grit refers to size of the particles on the paper that
remove wood
• Smaller numbers = coarser grit and faster removal
• Larger numbers = finer grit and slower removal
• Coarse (40-80) to fine (400, 600, 1,000)
• Steel wool ranges from 0 (very coarse) to 0000 (very
fine) threads of spun steel
Types of abrasive paper …
•
•
•
•
Note: sand is no longer used
Can be purchased in sheets or rolls
Flint paper – low cost, wears out quickly
Garnet paper – durable and low cost, but
cannot use wet
• Emery paper – durable, fine grits, expensive,
can’t use wet
More types of abrasive
paper …
• Emery cloth – like emery paper but backed
with cloth, can be used wet, used on metal
• Aluminum oxide paper – fast-cutting, longlasting, used with machine sanders, expensive
• Silicone carbide paper – durable, can be used
wet, very fine grits, inexpensive
Using abrasive papers:
• Sanding lumber after planing:
– Sand the first time using a 100 to 120 grit to
remove any planing or milling marks.
– Sand all marks from sawing
– Sand in the direction of the grain of the wood.
• After assembly:
– Sand before applying finish
– Some spots may need sanding before assembly
Sanding by hand:
• Sanding block prevents gouging irregularities
into the wood
– Purchase or make blocks from wood
– Most comfortable are flexible, rubberlike
• Sanding pads
– Thick foam, plastic or other flexible backing
– Easily sand contours in wood
Hand sanding techniques:
•
•
•
•
•
Use progressively finer abrasive
Switch to finer grade when wood is smooth
One grade finer until you reach 220 grit
Vacuum when sanding is complete.
Use a tack cloth to pick up final dust.
Using steel wool:
• Composed of finely spun fibers of steel
• Usually used with paint and varnish remover
to strip before refinishing
• Can leave fine particles hard to remove
• Very fine steel wool sometimes used between
coats of varnish or other finish
Rubbing compounds:
• Usually made from finely ground pumice stone
• Comes as a fine powder to be mixed with water or oil
or already mixed in a waxlike compound
• Used to smooth out irregularities in the final finish to
give a very smooth, glassy final finish.
• Used with a hard finish such as lacquer or with wellcured polyurethane finishes
• Rubbed into the surface with a soft cloth until the
surface is smooth
• Wiped off at the end
Selecting
and Using
Plywoods
What is plywood?
• A wood product made
of veneers (thin sheets
of wood) glued together
• Layers of veneer are
glued perpendicular
to each other
(at 90 degree angles).
How is plywood made?
1. Veneer logs are carefully selected and cut to the
proper length.
2. A log is softened with steam and mounted on a
lathe.
3. A knife peels off a thin layer of wood in continuous
veneer sheets.
4. As many as 5-6 layers are glued.
5. The glued stack is heated under pressure.
Who uses plywood?
• Plywood was discovered by Egyptians, Romans
and Chinese.
• Strength is added by perpendicular placement
of layers.
• Construction uses:
– Subfloor
– Wall sheathing
– Roof sheathing
– Furniture
Kinds of plywood
• Grading is done by:
– Quality of exterior layers
– Glue's ability to tolerate moisture
• Classified into 2 grades:
– INTERIOR: Glue holding the veneer
layers together weakens when it
becomes wet.
– EXTERIOR: Glue can withstand
dampness and can remain strong
and usable when exposed to weather.
OK!
Classified by quality of veneers:
• Both outside letters are given a letter grade.
• The higher the letter, the better the grade
• For example: sheet graded as AD
– Top side graded A is smooth and paintable.
– Bottom side graded D has knots and knotholes up
to 2 ½” across the grain.
How the veneer grades
stack up:
• Grade A: paintable, can be used for natural
finishes, synthetic repairs are permitted. No
more than 18 neatly made repairs. A synthetic
repair uses wood filler as opposed to a wood
patch.
• Grade B: solid surface with impurities – shims,
circular repair plugs and tight knots up to 1"
across grain. Synthetic repairs and minor splits
permitted.
How the veneer grades
stack up (cont.):
• Grade C plugged: improved C grade veneer. Splits
limited to 1/8" and knotholes limited to 1/4" X 1/2".
Synthetic repairs permitted.
• Grade C: Tight knots up to 1 1/2" and synthetic or
wood repairs permitted. Discoloration or sanding
defects, which do not impair strength, are permitted,
and limited splits are allowed.
• Grade D: Knots and knotholes up to 2 1/2" across
grain and 1/2" larger within specified areas. Stitching
permitted, limited splits allowed, limited to interior
use and exposure 1 and 2 panels.
How plywood is sold:
• 4’ x 8’ sheets
• Common plywood thicknesses:
– ¼”
– 3/8”
– ½”
– 5/8”
– ¾”
– 1”
American Plywood Association
labels include …
•
•
•
•
•
•
•
•
Panel grade
Span rating
Thickness
Square or tongue-and-groove edge
Code of recognition of the APA
Exposure durability
Mill number
APA’s performance-rated panel standard
APS plywood label …
Using Different
Types of Stains
and
Finishes
How are stains and clear finishes
used?
Stains
Clear finishes
• Color wood to
different shades
• Highlight the wood
grain
• Protect wood
• Allow the beauty of
the wood to show
through
More about stains …
• Stains penetrate wood and can highlight the
wood grain.
• Water-based stains are easier to clean up.
• Oil-based stains penetrate more deeply and bring
out the grain of the wood.
• Apply to bare wood.
• Prepare wood with very fine grit sandpaper.
• Carefully remove all dust.
Applying stain:
•
•
•
•
Apply with lint-free cloth or clean brush.
Make sure all parts are covered.
Let it stand for about five minutes.
Use a soft, lint-free cloth to remove the excess
stain.
– A clean, dry brush can be used to remove excess
stain from cracks
– Keep wiping until the stain is even.
– If blotchy, wipe with a cloth dipped in mineral
spirits and begin again.
After the first coat:
• Let the stain set overnight.
• Fine wood fibers will stand up – called
raising the grain.
• Lightly sand with 220 grit sandpaper and
use a tack cloth to pick up all dust.
• Apply a second coat of stain and let dry
overnight.
Fillers …
• Woods like oak, walnut and mahogany have
what is known as an open grain.
– Large surface pores
– Wood filler may be needed for smooth finish
• The filler may contain stain or dry clear
– Wipe on with a cloth
– Let dry overnight
– Sand lightly
• Apply finish
5 types of clear finish common on
wood:
1.
2.
3.
4.
5.
Oil finish
Varnish
Polyurethane
Epoxy
Lacquer
Basics on clear finishes:
• Use on bare wood or over stain.
• Follow instructions if combining products.
• Usually okay to combine water- and
oil-based finishes.
• Prepare wood first and remove dust.
• Apply finish in a dust-free environment.
Oil finishes:
•
•
•
•
•
•
•
•
Bended oils like linseed oil or tung oil
Rubbed into wood with cloth
Does not contain hardeners like varnish does
Generously applied to bare wood and allowed to soak
in
Remove excess with a soft, clean cloth.
Dry overnight and sand lightly with 220 grit paper.
Remove dust and apply more oil.
Several coats are needed.
Pluses and minuses of oil finishes:
Advantages:
• Penetrate the wood
and become a part of
the wood
• Deep, rich-looking
finish
Disadvantages:
• Tend to become dark
over time
• Not as durable as other
finishes
• Tend to dry out over time
CAUTION: Discard all oily rags in an
approved container to prevent
spontaneous combustion.
Varnish:
• Made from a variety of different natural oils, often
linseed oil and tung oil
• Hardeners are added to seal wood and repel
moisture.
• Comes from plant sources – linseed oil from flax
seeds, tung oil from the nuts of the tung tree.
• Does not adhere well to bare wood, so requires a
sealer
• Spar varnish is water resistant
• Applied with a natural bristle brush
• Needs two coats
The good and bad side of varnishes:
Advantages:
• Easy to use
• Brush on or apply with
a wool applicator
Disadvantages:
• Darken with age
• May become soft
• Not as durable as
some of the newer
finishes
Polyurethane finishes:
• Composed of synthetic materials
• Clear, durable and resistant to water
• Some types can be used outside and may even
be resistant to such solvents as alcohol.
• Used extensively on wood floors.
• Applied like varnish except
– Applied directly to bare wood or over stain
– Certain types may be rubbed on with a cloth.
How polyurethane finishes stack up:
Advantages:
• Easy to apply
• Goes on smooth with
brush or soft cloth
• Durable
• Long-lasting finish
Disadvantages:
• Can be expensive
• Difficult to remove
• Brushed finish can
have a heavy, shiny
appearance that looks
like plastic
• Newer wipe-on types
look better
Epoxy finishes:
• Most durable of all of the clear wood
finishes
• Used by mixing two parts just before it is
applied
• Brushed on
Using epoxy finishes:
Advantages:
• Flexible
• Resists abrasion,
solvents, chemicals,
water and heat
Disadvantages:
• Expensive
• Difficult to apply
• Appearance not as
high quality as some
other clear finishes
Lacquer:
• Most often applied with a spray gun
• Newer types of lacquer may be applied
with a brush
• Dries almost instantly
• Hard, durable finish
Do you lacquer or not?
Advantages:
• Dries so quickly that
several coats can be
applied in a single day
• Can be rubbed smooth
with rubbing
compound
• Provides a hard,
durable finish
Disadvantages:
• Spray equipment is
expensive.
• Equipment must be
cleaned after use.
• Finish may be marred
by water.
Woodworking and Construction
Careers
Would I enjoy a forestry or
wood products career?
• Many foresters have a natural interest in
conservation and the environment.
• Forests are multiuse: timber, wildlife and
recreation.
• Silviculture studies the development,
cultivation and reproduction of forest trees.
• Wood products technology improves and
develops new wood products.
A challenging career ...
• Forests and woodlands
make up 1/3 of U.S. land
area
– Individuals own 58%
– Forest products companies
own 14%
– Balance is state and national
forests
Forests provide:
• Essential commodities like:
– Lumber, veneer, wood panels
– Wood pulp, paper
– Cellulose, chemicals
• Recreation and scenic areas
– Home for wildlife
– Cleaner air and water
– Soil conservation
Forests are a
renewable resource.
• It will take work and knowledge to use and
maintain forests for future generations.
• Demand for wood products on the increase
– 1.6 billion trees must be replanted yearly
– Most replanting by industry and private owners
Where could I work
in a forestry career?
• In the forest
• Mills, offices,
laboratories
• Classrooms, board
rooms
• Legislatures
• Laboratories
Employment in the timber
industry:
• Planting trees
• Tree nurseries
• Marking trees for
harvest
• Purchasing or
marketing timber
Employment in construction,
furniture, packaging or paper:
•
•
•
•
•
Technical, management, marketing
Research
Manufacturing adhesives, chemicals, plastics
Wood machinery and equipment
Prefabricated wood products, plywood and
veneer
Federal employment:
•
•
•
•
U.S. Forest Service
National Park Service
Bureau of Land Management
Supervise recreation, conservation,
watersheds
• Administer timber sales and leases
Other employment:
• State extension service
• Forestry associations
• County and municipal governments
What training will I need?
• Foresters generally have at least a 2-year
degree
• Bachelor's degree helpful for a professional or
management position
• Master's or Ph.D. for research or teaching
Unit 1: Woodworking Identifying
Types and Grades of Lumber
Board Feet (FBM)
• 1. Board foot = L x T x W
•
12
• Divide by 12 if length is in feet
• Divide by 144 if length is in inches
2. Materials used in farm
construction
• Three major kinds of materials used in farm
construction:
• Wood, steel & masonry
3. Classifications of lumber
• Two Classifications of lumber:
• Softwoods - pine, cedar, fir, redwood, cypress
• Hardwoods - oak, ash, birch, cherry, sycamore,
walnut, hickory, maple
• Almost impossible to nail hardwoods & in
knots in softwoods
4. Farm Buildings
• Made of softwoods
5. Grades of softwoods
• Two grades of softwood
• Common
• Select - knot free for finish work
6. Uses of common lumber
• Common No. 1 & 2 used for rafters & joist
• Common No. 3 used for studs & plates
• Common No. 4 & 5 where strength is not a
factor
7. Dressed lumber
• A dressed 1” x 4” is actually
• 25/32” x 3-5/8”
8. Lumber for specific jobs
•
•
•
•
•
concrete forms-pine,fir No. 1 & 2
framing building-pine & fir No. 1,2,3
roof sheeting-pine & fir No. 2 & 3
siding-redwood & cedar
floors-pine & oak select lumber others above
are common grades
Fencing materials
• When selecting fencing consider:
• 1. type of livestock
• 2. permanency
Types of paint
•
•
•
•
1. exterior 2. interior
3. floor 4. roof
5. enamel 6. barn
7. masonry 8. metal or implement paint
Rafter length formula
•
•
•
•
a squared + b squared = c squared
take square root of c squared
subtract half the thickness of ridge board
add length of overhang
c
b
a
Draw a bill of materials for a
project
Assignment #2
Drawings and sketches
Creating woodworking project plans using
simple drawing techniques.
4. Purpose of drawings and
sketches
Overcome mechanical,
construction and repair
problems
5. Plans (drawings)
Are your most important
guide
8. Advantage of having a bill
of materials
Saves time and waste
7. Bill of materials
Amount, size and kind of
each item needed to
construct something
Application make a projection
drawing of a
woodworking project
such as an Ag. in the
Classroom Storage Chest
(include a top, front ,
right end views and a bill
of materials).