What is linear measurement? A system for measuring length Measuring devices, also called layout tools, are used to measure length. Examples of tools

What is linear measurement?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 tapesand dividers

Photo courtesy of Snap-on Tools.

Purpose of linear measurements: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 …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 Materials for measuring devices (cont.) …(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 Materials for measuring devices (cont.) …(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 …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 English/U.S. customary system of measurements …measurements …

• Uses inch, foot, yard, rod and mile• INCH – traditional U.S. unit for

woodworking and metalworking

Metric system of measurement …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:Common tools for linear measurements:

• Tapes, rules and scales• Last number on the scale is read plus any

fraction

Measuring tape: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

with care Photo courtesy of Snap-on Tools.

Folding rule: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: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:

• 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

16” wide

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 areeven–Crossways mounted

tube can be used toplumb 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. Measure and mark the desired length.2. Place handle firmly against board edge.3. Move the blade against the mark.4. 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. Power cord 2. Handle 3. Motor housing 4. Gear chuck 5. Vents 6. Trigger switch 7. Trigger switch lock 8. Reversing switch 9. 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 115-

volt 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 courtesySnap-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. Use even pressure on the drill. 8. 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 So what’s the big deal about hand tools?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:Advantages to hand tools:• Can be used without electricity• Sometimes more appropriate than power

tools• No set-up needed

Classifying hand tools: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: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:Layout tools – examples:

Photos courtesy of Snap-on Tools.

Cutting tools:Cutting tools:• Chop, cut, saw or

otherwise removematerial• 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: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: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:Handsaw details:

Boring tools: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: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:Hammers and mallets:

Holding tools: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:Holding tools – examples:


Turning 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:Turning tools – examples:


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 stainand 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 largersurfaces–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. Clean machine bed of all rust.2. Use fine steel wool or 400-grit paper.3. Wipe away loosened rust.4. Apply wax in circular motion.5. Allow wax to dry to a haze.6. Buff wax with soft cloth.7. 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.


9. Use a handsaw to make akerf across the longestcenter line of the handle.The kerf should extendtwo-thirds of the distancebetween the two marksin 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.


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 insecurely with a plastic, leather, rubber or wooden mallet. (Steel hammers can ruin wooden handles.)

14. Grip the handle with the vise justbelow the head.


15. Use a hacksaw to saw off the excesshandle flush with the head.

16. Drive the wooden wedge so thehandle spreads and fills the head.

17. Use a hacksaw to saw off the excesswooden wedge.

18. Drive one or two metal wedges in atright angles to the wooden wedge tohold the wedge in place.


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 fingercalled a tang which isdriven 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: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 …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:More about finishing sanders:

• They move randomly, so sanding can be done with the grain or across the grain.• Almost all finishing

sanders are orbitalsanders, moving ina random circularpattern that resultsin a faster cut, butgives a fine finish. Photo courtesy Snap-on Tools.

Main parts of a belt sander:Main parts of a belt sander:

• The belt sander has a moving sanding belt.1. Motor housing2. Handles3. Belt4. Belt rollers5. Belt adjustment6. Trigger switch7. Switch lock8. Power cord9. Dust bag

Safely operating a belt sander: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.


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.


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.


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 Parts of portable disc sanders/grinders: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 housing2. Handles3. Power cord4. Switch or trigger5. Switch lock6. Cooling vents7. Wheel8. Spindle9. Safety guard10. Tool rest

More on sanders and grinders: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:Examples of sanders and grinders:

Disc sander: Grinder:

Photos courtesy Snap-on Tools.

Safety precautions when using a Safety precautions when using a grinder: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 one-half

its original diameter. • Secure small pieces in a vise, if possible.

Safety precautions when using a Safety precautions when using a grinder (cont.):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: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 Sander or grinder procedures (continued):(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:Parts of a finishing sander:

1. Motor housing2. Handles3. Switch4. Switch lock5. Power cord6. Paper clamps7. Pad8. Sandpaper

Procedures for using a finishing Procedures for using a finishing sander …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 frequently8.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 star-

or 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 frompenetrating material.

• Special lock washersprevent nuts or boltsfrom 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 underpressure.

• Chemicals preventwood decay andinsect 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 toplants and animals• Be careful when choosing

pressure-treated lumberfor 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 abrasivepaper …

• Emery cloth – like emery paper but backed with cloth, can be used wet, used on metal• Aluminum oxide paper – fast-cutting, long-

lasting, 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 well-

cured 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 sheetsof wood) glued together• Layers of veneer are

glued perpendicularto 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 itbecomes wet.–EXTERIOR: Glue can withstand

dampness and can remain strongand 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 gradesstack 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 gradesstack 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 How are stains and clear finishes used?used?

Stains• Color wood to different

shades• Highlight the wood grain

Clear finishes• Protect wood• Allow the beauty of the

wood to show through

More about stains …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: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: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 …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 5 types of clear finish common on wood:wood:

1. Oil finish2. Varnish3. Polyurethane4. Epoxy5. Lacquer

Basics on clear finishes: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: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:Pluses and minuses of oil finishes:

Advantages: • Penetrate the wood

and become a part of the wood

• Deep, rich-lookingfinish

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: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: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: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 How polyurethane finishes stack up: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: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: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: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?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 orwood 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 arenewable 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 workin 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:Unit 1: Woodworking Woodworking Identifying Identifying Types and Grades of LumberTypes and Grades of Lumber

Board Feet (FBM)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 2. Materials used in farm constructionconstruction

• Three major kinds of materials used in farm construction:

• Wood, steel & masonry

3. Classifications of lumber 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 Buildings4. Farm Buildings

• Made of softwoods

5. Grades of softwoods5. Grades of softwoods

• Two grades of softwood• Common• Select - knot free for finish work

6. Uses of common lumber6. 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 lumber7. Dressed lumber

• A dressed 1” x 4” is actually• 25/32” x 3-5/8”

8. Lumber for specific jobs8. 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 materialsFencing materials

• When selecting fencing consider:• 1. type of livestock• 2. permanency

Types of paintTypes of paint

• 1. exterior 2. interior• 3. floor 4. roof• 5. enamel 6. barn• 7. masonry 8. metal or implement paint

Rafter length formulaRafter 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

abc

Draw a bill of materials for a project

Assignment #2

Drawings and sketchesDrawings and sketches Creating woodworking project plans using Creating woodworking project plans using

simple drawing techniques.simple drawing techniques.

4. Purpose of drawings and sketches

Overcome mechanical, Overcome mechanical, construction and repair construction and repair problemsproblems

5. Plans (drawings)

Are your most important Are your most important guideguide

8. Advantage of having a bill of materials

Saves time and wasteSaves time and waste

7. Bill of materials

Amount, size and kind of Amount, size and kind of each item needed to each item needed to construct something construct something

Application-

make a projection make a projection drawing of a woodworking drawing of a woodworking project such as an Ag. in project such as an Ag. in the Classroom Storage the Classroom Storage Chest (include a top, front Chest (include a top, front , right end views and a bill , right end views and a bill of materials).of materials).

Documents

What is linear measurement? A system for measuring length Measuring devices, also called layout tools, are used to measure length. Examples of tools