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Demonstrating Measuring Devices


Title: Slide 1 Author: Joe W. Kotrlik Last modified by: Joe W. Kotrlik Created Date: 7/17/2008 3:21:57 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Demonstrating Measuring Devices

Demonstrating Measuring Devices
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,
    scratchawls, calipers,measuring tapesand

Photo courtesy of Snap-on Tools.
Purpose of linear measurements
  • Measure and mark materials before cutting or
  • 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

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

Measuring tape
  • Flexible measuring device that rolls into a case.
  • Several feet to hundreds of feet
  • Steel, cloth or fiber
  • Often self-retracting withlocks or buttons
  • Usually has end hook
  • Easily broken handlewith care

Photo courtesy of Snap-on Tools.
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 whenopening and closing

  • 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

Applying Geometric Princples
Why use squares, levels and lines?
  • Measuring angles and cutting accurately are
    essential for the success of any construction
  • 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 squareand a steel
  • May contain tables to calculateboard feet and
  • Has both inside and outsidemeasurements

16 wide
24 long
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 boardsup to 12
  • Used to draw 90 or 45lines 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 lineswhen both ends areeven
  • Crossways mountedtube can be used toplumb an

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

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.

Indentify and Demonstrate Common Tools - Drill
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
  • 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
    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

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
  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
  1. Use even pressure on the drill.
  2. Ease off the pressure when the drill is breaking
    through the material.
  3. Hold the drill so as to avoid binding the drill
  4. Position yourself so that balance is always
    maintained never lean on a drill.
  5. Remove the drill bit from the chuck when
  6. 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.

Indentify and Demonstrate Common Tools Hand Tools
  • Ag Engineering Library

So whats 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
  • 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
  • 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 orotherwise removematerial
  • Permit user to shapematerial
  • 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.
  • 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
  • Teeth determine use.
  • Filed to a point cut across the grain of boards
    (crosscut saws)
  • Filed to a knifelike edge cut with the grain

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
  • 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

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
  • Often used to install a fastener in wood or other
  • 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.
Removing and Preventing Rust
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

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.

Its 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 youre 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
  • 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
  • Dry metal thoroughly.
  • Coat all smooth metal surfaceswith light oil.
  • Use heavier oil for rougher surface.

Dont leave oil on some surfaces
  • Beds of stationary power woodworking tools
  • Oil will contaminate wood.
  • Use a high-quality paste wax on the surface

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

Replacing Handles
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
  • Place the head securely in a vise.
  • Use 1/4 or 3/8 metal cutting bit to drill
    numerous holes in the wooden core.
  • 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
  4. Try the head frequently as wood is removed to
    avoid a loose fit.

Attaching a hammer or axe handle (cont.)
  1. 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.
  2. Mark the handle on both sides of the head.
  3. Remove the head.
  4. 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.)
  1. 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.
  2. Reposition the handle in the vise and squeeze the
    end until the saw kerf is completely closed.
  3. 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.)
  1. Make a wooden wedge as wide as the oval hole in
    the head and thick enough to spread the handle
    when driven in.
  2. Slide the handle in and drive it insecurely with
    a plastic, leather, rubber or wooden mallet.
    (Steel hammers can ruin wooden handles.)
  3. Grip the handle with the vise justbelow the

Attaching a hammer or axe handle (cont.)
  • Use a hacksaw to saw off the excesshandle flush
    with the head.
  • Drive the wooden wedge so thehandle spreads and
    fills the head.
  • Use a hacksaw to saw off the excesswooden wedge.
  • Drive one or two metal wedges in atright angles
    to the wooden wedge tohold the wedge in place.

Attaching a hammer or axe handle (cont.)
  • Place the tool, head down, into a metal or
    plastic container about the size of the head.
  • Add several inches of boiled linseed oil and
    brush oil around the handle and head.
  • The handle and head should soak in the oil
    several days to seal the wood.
  • 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
  • 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
  • Handles are made to fit specific shovels.

How to attach a shovel handle
  1. Grind off the head of the rivet that holds the
  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.)
  1. Use a vise to close the metal around the handle
    and secure the assembly while drilling.
  2. Insert a drill through the hole in the metal and
    drill through the wooden handle.
  3. Install the replacement rivet securely, being
    careful to keep the metal tight to the wood.

Selecting and Using Portable Sanders
  • 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 finishingsanders 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
  • 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
  1. Wear suitable face protection and protective
  2. Check the power cord and extension cords for
  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

Safely operating a belt sander
  1. Always start the machine while holding it
    slightly above the material.
  2. Keep the power cord out of the way of the belt.
  3. 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.
  4. Operate the machine with two hands at all times.

Safely operating a belt sander
  1. 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.
  2. Keep the machine in motion, letting the weight of
    the sander do the work without applying pressure.
  3. The final movement is to lift the machine off the
    work while it is still running.

Safely operating a belt sander
  1. Examine the work carefully. Resand if necessary
    to create a smooth, perfectly level surface.
  2. Install a fine sanding belt and resand. This
    resanding leaves the work in its smoothest
    possible form using a belt sander.
  3. 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 housing2. Handles3. Power cord4.
    Switch or trigger5. Switch lock6. Cooling
    vents7. Wheel8. Spindle9. Safety guard10.
    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
  • Grinder

Photos courtesy Snap-on Tools.
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
    one-half 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
  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)
  1. Touch the work gently with the wheel to avoid the
    wheel catching the work and throwing metal
  2. Do not apply pressure to the machine.
  3. After turning the switch off, do not lay the
    machine down until it has completely stopped.
  4. Do not lay the machine down on its disc or wheel.
  5. Remove the grinding wheel or sanding disc and
    store the machine properly after use.

Parts of a finishing sander
  • 1. Motor housing2. Handles3. Switch4. Switch
    lock5. Power cord6. Paper clamps7. Pad8.

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
  • 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
  • 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
  • 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
  • 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
  • Solid brass screws are rustproof and used where
    severe moisture problems destroy coated or plated

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
  • 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
  • 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 extensionsfor tightening
  • Special nuts with slotsallow cotter pins
  • Graded by strength

What is a washer?
  • Flat device with a holein the center
  • Used as part of a fastener
  • Flat washers prevent boltheads 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 driveninto the wood
  • 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

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.

  • These chemicals areharmful or toxic toplants
    and animals
  • Be careful when choosingpressure-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
  • Year of chemical treatment
  • The preservatives used in treating the lumber
  • Trademark of bureau supervising the treatment
  • Proper exposure conditions
  • Treating company's location
  • Dry or KDAT if applicable

Safety observations
  • Wear gloves when handling pressure-treated
  • 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
  • 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,
    cant 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,
  • 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
  • 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 madeof veneers (thin sheetsof
    wood) glued together
  • Layers of veneer areglued 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
  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
  • Strength is added by perpendicular placement of
  • 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 veneerlayers together
    weakens when itbecomes wet.
  • EXTERIOR Glue can withstanddampness and can
    remain strongand usable when exposed to weather.

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
  • Grade B solid surface with impurities shims,
    circular repair plugs and tight knots up to 1"
    across grain. Synthetic repairs and minor splits

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

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
  • APAs performance-rated panel standard

APS plywood label
Using Different Types of Stainsand Finishes
How are stains and clear finishes 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
  • Stains penetrate wood and can highlight the wood
  • 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
  • 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

  • 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. Oil finish
  2. Varnish
  3. Polyurethane
  4. Epoxy
  5. Lacquer

Basics on clear finishes
  • Use on bare wood or over stain.
  • Follow instructions if combining products.
  • Usually okay to combine water- andoil-based
  • 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
  • Remove dust and apply more oil.
  • Several coats are needed.

Pluses and minuses of oil finishes
  • Advantages
  • Penetrate the woodand 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.
  • Made from a variety of different natural oils,
    often linseed oil and tung oil
  • Hardeners are added to seal wood and repel
  • 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
  • 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
  • Brushed on

Using epoxy finishes
  • Advantages
  • Flexible
  • Resists abrasion, solvents, chemicals, water and
  • Disadvantages
  • Expensive
  • Difficult to apply
  • Appearance not as high quality as some other
    clear finishes

  • Most often applied with a spray gun
  • Newer types of lacquer may be applied with a
  • Dries almost instantly
  • Hard, durable finish

Do you lacquer or not?
  • Disadvantages
  • Spray equipment is expensive.
  • Equipment must be cleaned after use.
  • Finish may be marred by water.
  • 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

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
  • 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
  • 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 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
  • 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

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

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

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

  • 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).