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Workshop Theory and Basic Mechanics

(GC-5)

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Hand tools and measuring devices

Objective • Students be able to:

– Identify major types of hand tools and their parts.– Explain the purpose of these tools – Explain the purpose of these measuring device – Understand the caring of tools– Recognize basic safety ,care, and storage of tools

remain the same. –

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Content • General Safety tips• Pounding tools• Turning tools• Cutting tools• Measuring tools• Clamping tools• Laying out and lay out tools• Abrasive tools• Power tools• Workshop theory and application

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I. General Safety Tips

• Be clean and neat –Happy worker

• Dress safely - Avoid loose fitting.

• Avoid hazards associated with the use of hand and power tools.

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Hand Tools --Safety

• Keep all tools in good condition with regular maintenance.

• Use the right tool for the job.• Examine each tool for damage before use

and do not use damaged tools.• Operate tools according to the

manufacturers’ instructions.• Provide and use properly the right personal

protective equipment.

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Power Tools -- Safety

• Never carry a tool by the cord or hose. • Never yank the cord or the hose to

disconnect it from the receptacle. • Keep cords and hoses away from heat, oil,

and sharp edges. • Disconnect tools when not in use, before

servicing, and when changing accessories such as blades, bits and cutters.

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Power Tools -- Safety• Instruct all observers to stay at a safe

distance away from the work area.

• Secure small work surfaces with clamps or a vice so that you can use both hands to operate the tool.

• To avoid accidentally starting the tool, the worker should not place a finger on the switch button while carrying a plugged-in tool.

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Power Tools -- Safety• Maintain tools with care. Keep them sharp

and clean for the best performance, and follow instructions in the user's manual for lubricating and changing accessories.

• Maintain good footing and good balance. • Wear the proper apparel - loose clothing or

jewellery can become caught in moving parts.

• Remove all portable electric tools that are damaged from use and tag them "Do Not Use."

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II. Pounding Tools

Tools used to strike heavily and repeatedly – hammers.

• TypesMetal head – hard hammers

Soft head - mallets

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Hard Hammers

• Nail

• Ball peen

• Cross/straight

• Tack / riveting• Sledge …`(rarely applicable in aviation)

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Principal Parts

• Handle

• Eye

• Poll

• Neck

• Cheek

• Ball peen / cross peen …

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Nail Hammers

• For common and finishing nails and nail sets.

• NOT FOR masonry nails, cold chisels, or other metal.

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Ball Peen Hammers

• For cold chisels, punches, rivets, and shaping metal.

• Stretching, forming,bending

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Straight / Cross Peen Hammer• For general sheet

metal work

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Sledge Hammer

• Not common in a/c work

• For heavy steel work, forgings.

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Soft Hammer

• Can be made with– Plastic, Rawhide, Wood, Brass, Copper, Lead

• Heavy blows without causing damage

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- Using a hammer or mallet chose the one best suited for the job.

-Ensure that the handle is tight - Always strike the work squarely with the full face of the hammer -Always keep the faces of hammer s and mallet s smooth and free from dents ,chips ,or gouges to prevent marring the work

Soft Hammer

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IV. Turning Tools • Wrenches• Screw drivers

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• Can be classified by it shape ,type of blade and blade length

• The main purpose for tightening and loosing screw and screw head bolts.

• Using the common screw driver ,select the largest screwdriver whose blade will make a good fit in the screw that is to be turned

• Screwdriver must fill at least 75% of the screw slot

Screw driver

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Screw driver- If the screwdriver the wrong size of , it cuts burrs

the screw slot ,making it worthless - Slip and damage adjacent parts of the structure- damage may be so severe that the use of screw

extractor may be required - Two type of recessed head screws in common heads

uses are the Phillips and Reed and prince recessed head

- Both the Phillips and Reed and prince recessed heads are optional on several types of screw

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-An Offset screw divider may be used when a vertical space is limited

- Offset screw dividers are constructed with both ends bent 90 degree to the shank handle .

- Screw dividers should never be used for chiseling or prying

- Do not use a screw driver to check an electric circuit since an electric arc will burn the tip and make it useless .

- When using a screw driver on a small part always hold the part in the vise or rest it on work bench .

Screw driver

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-Do not hold the part in the hand ,as the screwdriver may slip and causes serious personal injury

- Replicable tip screwdriver Some times preferred for the quick changing of screwdriver tip ,it become worn .It is economical .

- Power screwdriver has replaced most automatic or spiral screwdrivers for the removal of multiple screws from an airframe .

- Care must be exercised when using a power screwdriver

Screw driver

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wrenches - Most often used in air craft maintenance are classified as open end, box-end , socket ,adjustable, ratcheting and special wrenches - One of the most widely used metals for making wrenches is chrome-vanadium steel. -The Allen wrench is required on one special type of recessed screw.

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wrenches

A socket wrenched is made of two parts

1.The socket ,which is placed over the top of a nut or bolt head

2.A handle ,which is attached to the socket

Many types of handles, extension s, and attachments are available tomake it possible to use socket wrenches in almost any location or portion They have either a four, six , or twelve-sided recess a nut or bolt that needs regular adjustment .

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Adjustable wrench is a handy utility tool that has smooth jaws and is designed as an open-end wrench .one jaw is fixed, but the another may be moved by a thumbscrew or spiral screwworm adjustment in the handle .

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wrenches

-Box-end wrenches are popular tools b/c of their usefulness in close quarter , Since they are completely surrounded the nut or bolt head we call box wrenches

-

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wrenches

Special wrenches- Crowfoot- accessing nuts must be removed from studs or bolt that can not be accessed using other tools

-it can be used in conjunction with a torque wrench

- flare nut-appearance of a box end wrench that has been cut open on one end

-be use on the B-nut of a fuel, hydraulic, or oxygen line

-it can be used in conjunction with a torque wrench

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-Spanner-the hook spanner is for around nut with a series of notches cut in the outer edge

-has a curved arm with a hook on the end that fit one of the notches on the nut-the hook is placed in one of these notches with the handle pointing in the direction the nut is to be turned

- Torque- there are times when definite pressure must be applied to a nut or bolt as it is installed . In such cases a calibrated torque wrench must be used . - before each use ,torque wrench should be visually inspected for damage - commonly used torque wrenches include the deflecting beam (not shown) , dial indicating , micrometer, and electronic setting types. -

- Allen

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III. Metal Cutting Tools

• Hand Snips

• HackSaws

• Chisels

• Pliers

• Shears

• Files

• …

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Hand Snips – there are several kinds of hand snips ,each of which serves a different purpose.

-Straight – used to cut straight - Curved - cutting inside of curves or radii - aviation snips – usually designed especially for cutting heat treated Aluminum alloy and stainless steel Unlike the hacksaw , snips do not remove any material when the cutIs made ,but the minute fracture often occur along the cut

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Hacksaws1- Select the appropriate saw blade for the job 2- Assemble the blade in the frame so that the cutting edge of the teeth points away from the handle 3- Adjust tension of the blade in the frame to prevent the saw from buckling and drifting 4- Clamp the work 5- Indicate the starting point 6- Hold the saw at an angle that it will keep at least two teeth in contact 7- after the first few strokes ,make each stroke as long as The hacksaw frame will allow . This will prevent over heating 8- clean, remove chips ,loose tension on the blade

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Chisels - It is a hard steel cutting tool that can be used for cutting and chipping any metals softer than the chisel it self

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FilesMost files are made of high-grade tool steels that are hardened and

tempered. Size of file The size of the file is indicated by its length For general work 200mm to 450mmFor fine work 100mm to 200mm

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FilesCut of teeth 1- Single cut files – cut parallel to each other running across the faces and at angle of 60degree to the center line of the file

-Used for very hard work

2- Double cut files – there are two sets of teeth . The first set of teeth similar that of single cut file (60 degree) While the second set of teeth cuts diagonally at 80 degree

-It removes metals faster and is used for general work

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Grade of cut of fileDepending on the pith of the teeth A.ROUGH –it used heavy reduction B. BASTARD- it used reducing bulky work C. SMOOTH – smoothing surface and filing delicate work. D. DEAD SMOOTHE. SUPER SMOOTH used by tool maker s and silver smiths for high accuracy and finish

Shape of file - Flat file - Knife edge file -Square file - Needle file …- Pillar file - Triangular file -Round file-Half-round

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METHOD OF FILING1.Cross- filing- it is the most common method of filling for general shaping work -It is used for efficient removal of maximum amount of metal in the shortest possible time 2. Straight filling – it is specially use full on long and narrow pieces of work whose width is less than that of the file. In this method the file stroke is made nearly at right angles to the length of the work 3. Draw filling- the draw filling is used to remove file marks and for finishing operation. For this purpose a fine cut file with a flat face should be used

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CARE OF FILE1.choose the right file for the material and the work to be performed 2. Keep the file racked and separated so they do not bear against each other3. Keep the files in a dry place4. keep the file s clean

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TWIST DRILLS

a pointed tool that is rotated to cut hole in a material

REAMERS - used to smooth and enlarge holes exact size

COUNTER SINK - a tool that cuts a cone shaped depression around the hole to allow a rivet or screw to set flush with the surface of the material

TAPS AND DIESTap- used to cut threads on the inside of a hole Die – is for cutting external threads on round stockMagic fingers – Mechanical - magnetic

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Pliers

• Slip joint – gripping and cutting. E.g. installation of cotter pins – water pump pliers.

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Diagonal Cutting Pliers – ‘Dikes’• Cutting of wire, cotter pins, nails, safety wire end.• Stripping of insulation from wires.

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Layout and measuring Tools

The six-inch steel rule •Can be used as a straight edge

•Usually contains four scales, 1/32, 1/64, 1/10, 1/100.

•The fractional divisions of an inch are found by dividing the inch into equal parts:

•Halves, quarters, eights, sixteenths, thirty- seconds and sixty-fourths or•Decimals of 100th of an inch

Measuring tools

• Combination set

Basic Measurement• Combination Set

– Can be used as a ordinary rule• 16ths, 32nds scales

- Scriber• used to draw a line

- Tri-square• 90°, 45° angles, Bubble Level

– Protractor• Precision angles

– Center head

• Used to find the center of an object

– Each head slides along the blade and can be locked

in place

• The Micrometer

– Handle with care

– Four types of Micrometers

• Outside

• Inside

• Depth

• Thread

– Precision measuring instrument

• Micrometer (Con’t)– Used to measure

• Thickness• Diameter• Other items

– Storing a Micrometer• Never tighten Anvil against Spindle, leave a

small opening• Store in a dry place, box, or pouch• If dropped, check for accuracy with Gauge

Block before using

• How to use and read a Micrometer

– Hold frame in palm of hand with little finger or

third finger inside the frame

– Tighten around object until ratchet clicks

– Micrometers with Vernier scale allow you to read

the fraction of the division on the barrel scale

– One revolution of micrometer is 0.025

– Gauge Block should be used to check calibration

• Least count of micro meter

• 0.1/4=0.025

• 0.025/25=0.001

• Less than this number we can not read

Compute the following micro meter reading

• Depth Micrometer– Used to measure

• Holes• Grooves• Recesses

– When using a Depth Micrometer:• Make sure base has a flat, smooth surface to rest

on• Hold firmly in place to prevent lift-off and

ensure an accurate measurement

How to use and read a Depth Micrometer– Graduations on the barrel are numbered in the opposite

direction of those on an outside micrometer

– Pay attention to numbers you can’t see

4 tenths + 25 thousandths + 10 thousandths= 0.435

• Calipers – Digital– Dial– Vernier

• Easy to read• Can be used to measure

• Outside

• Inside

• Depth

• Venire Caliper:– The main scale is divided in inches.

• Each inch is divided into 40 parts, like the sleeve on the micrometer

• Each division is equal to 0.025 inch – A movable jaw that matches the fixed jaw slides

along the main scale bar • Contains 25 divisions that equal 24 divisions on

the main scale

• How to read a Vernier Caliper:– Read the nearest number located on the main scale

(in inches) and add to that the number of subdivisions.

• Make sure to read from the zero on the movable jaw Make sure to read from the zero on the movable jaw Vernier scale and not the jaw edge!Vernier scale and not the jaw edge!

– Scan down the movable jaw Vernier scale and select the number that matches up exactly with the main scale

– Add this number to the numbers from the main scale

• Compute the following vernire caliper reading

• Solution

For inch measurement

1/40”is the least count of vernier caliper in the main scale but 1/(40/25)”=.001” the list count of the vernier caliper.

7 Is coincide number in the vernier scale

mm7078.49"957.17

2540

140

38"1

"

"

• For metric measurement

49+(1/50*38)=49.76mm1/50 =the least count of the vernier caliper

38 Is the number coincide with the main scale

• Ball gauges (Small Hole gauge)– Used to measure small holes up to ½ inch in

diameter– Insert ball gauge into hole and tighten– Remove ball gauge and use a micrometer to

determine size of hole by measuring 90 degrees to separation (spilt) on the ball gauge

– Store with ball retracted (backed-off)

• Telescoping Gauges– Used to measure inside cylinders, typically up

to six inches in diameter.– Allow spring loaded “T” gauge to extend to

inside opening– Lock shaft– Measure with micrometer– Store with ‘T” gauge extended

• Dial indicator-A precision instrument

-The linear movement of a spindle amplified by a gear train transmitted in to rotation of a pointer over a graduated dial

-The scale on the dial reads both to the right and the left of the zero and thus indicate the instrument is properly adjusted to any variation

-Determine the smoothness of concentricity of a surface

“v”blocks• Made up of either cast iron or steel in various size• A 90o V-shaped slot on both top and bottom• The size is usually grooved to receive the clamp yoke

which serves to hold the work securely in place while it is laid out or drilled

• Surface gauges- The Vertical spindle and the scriber can be

adjusted to and locked in any angular position

- Used to scribing horizontal line

- Used it for locating centers in rough

Using surface gage

Dividers and trammel

• Divider -A heavier spring joint type

-Use d fortransferring distance scribing arcs and circles on to the work

surface

Note

If the points are sharp enough to make clean ,precise scratch on a metal surface

calipers

• -used for measuring diameters and distance or

comparing distance and sizes

• The three common types of calipers are inside

out sidehermaphrodite

Out side calipers

• Measuring outside dimension -Ex diameter of round stock

Add fig

Inside caliper

• Have outward curved leg

• For measuring inside diameter

-Ex diameter of holes

add fig

Hermaphrodite

• Odd leg caliper

• Marking gauge in a layout work

• not be used for precision measurement

• Add fig

• protractors

• Go-no-go gage

Pitch gauges• Quickly identify the number of teeth per inch• Try to mesh the teeth of successive blades and you

will eventually find one that fits exactly• The number on the gage leave reveal the correct

thread pitch

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»End

»ANY QUESTION?

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