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transcript
8/6/2019 BENCH pptx Lecture Rommel
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BENCH WORK
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BENCH WORK
- the ability of using different hand
tools such as files, hack saw, hammer, screwdriver, drift punch, center punch, chisels,scraper, laying out tools and final fitting of
parts.
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SAFETY ON BENCH WORK
- most accidents to bench workers are
caused by thoughtless use of tools whichincludes using a tool incorrectly or carelessly.Many accidents result from using a tool to do
something for which it was not intended.
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FILES
1. Be sure that the file has a handle. See that thehandle fits securely. Never use a file without handle.
2. Remove burst and abrasion from the file handlebefore using it. They caused blisters.
3.Striking file with a hammer will also caused steelsplinters to fly.
4. Do not used files as a hammer. Flying pieces of hardened steel can pierce human skill.5. Using a file as a pry bar is a sure way of breaking it.
6. Keep file teeth clean of pins. Do not let oil and dirtcollect on the gullets of the file.
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HAMMERS
1.Always check the fit of the handle in thehammer head.
2. Do not used a hammer with a broken or splithandle.
3.Always remove oil, grease and dirt from theface and the handle of the hammer.
4. Never use the face of the hammer to strikeagainst another hardened tool.
5. Use the right size hammer for the job.
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WRENCHES
1. Keep wrenches clean, wipe off oil and grease before using thewrenches.
2.Stop any machine before using a wrench whether it is tootighten, loosen, remove or adjust, first stop the machine.
3. Be sure that the wrench fits the nuts snugly. An oversizewrench will slip and round off the corners of the nut.
4. Whenever possible, pull on the wrench, dont push.
5.Stand with proper balance whenever it is necessary to pull hardon a wrench one leg behind the other.
6. The design of the wrench provides a sufficient length for safeleverage.
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HACKSAW
1. Grip the work in the vise so that the saw cut will be near
the jaws.2.Apply pressure only on the forward stroke.
3.Start the saw cut with a light, even forward strokeholding the saw frame at an angle. When the cut isestablished, hold the frame level and saw the full width of the job.
4.Take the longest stroke possible but do not permit theblade supporting pins to touch the job.
5. Used blade having the proper number of teeth per inch tosuit the job fine pitch for thin metal, coarse piece for thickpieces.
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DRILL PRESS AND DRILLINGS
1. Think about what you are doing. Keep your mind on the job.
2. Dress safely. Remove rings, watches, identification bracelets andneckties. Roll up the sleeves.
3. Fasten the job or vise securely to the table.4. Remove tools, clamps, wrenches and so forth from the table beforestarting the drill.
5. Remove drill drift from the spindle or chuck key from the drill chuckimmediately after used.
6. When the drill become dull, re sharpen or replace it.
7. Grind the drill correctly for the metal it is required to cut.
8.As the drill breaks through the work, relieve the down feed pressure.
9.Stop the machine before measuring or adjusting the job.
10.Stop the machine before using a brush to remove chips and excesscoolant.
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GENERAL SHOP SAFETY
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CLOTHING no necklace, wristwatch, jewelries and only short
sleeves are advisable.
Should have apron shop coat or coveralls
Dont use woolen sweater ( long and unbrokenstrands)
Using canvass shoes (snickers)
When to use gloves (when moving pieces of stockwith sharp edges)
The importance of goggles.
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SHOP WORK
feet 8 to 12 inches apart and good balance
bend knees to distribute the load when carrying tothe person who would help you lift a load to haveaccurate movements.
Carrying long steel bars should be on the shoulder,
it should be vertical Dont leave pieces of stock on the floor
Grease on the floor isnt safe.
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A machinist must be skilled in the use of the
numerous hand tools which have been
designed to make his work easier.In addition,knowing how to used hand tools properly, the
machinist must also know the various types
of tools available to do a particular job and
how to care for and store the tools correctly.
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HAMMERS
Hammers were one of the mans earliest
tools. The types of hammer used by somemachinist are limited but they are available inmany sizes. Machinist hammer are classified
as hard or soft hammer.
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A hard hammer is one that is made of carbon
steel and forged to size and shape. It is heat
treated to make the striking faces hard.A soft hammer may have the entire head made
of a soft metal such as lead, copper or brass.
A soft-face hammer have only their strikingsurfaces made of plastic, rubber or rawhide.
The faces are either clamped or press fitted
on the metal hammerhead.
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USES OF HARD HAMMER
For st r iking:
Punches c. steel letters cold chisels d. figures
Hammer is also used for :
forging hot metal d.straightening
riveting e. pining
bending f. stretching
and swaging
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THE MOST COMMONLY USED HAMMER BY
SOME MACHINIST
1. Soft hammer with brass head
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2. Plastic-faced Soft hammer
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3. Ball-peen hammer and its part
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4.Straight peen hammer
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5. Cross-peen hammer and its part
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The sized of the hammer is specified by
the weight of the head without the handle.
Ball-peen hammer sizes ranged from 2onz to3lb.
Size of the soft face hammers are
specified by the diameter of the face and the
length of head and range from 5/8 inchdiameter o 3 inches diameter. Faces arespecified in degrees of hardness from super
set to extra hard
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hand punch
is a tool held by hand against the work
piece. The end in contact with work piece isshaped to do a particular job whereas theother end is flat so that it could be struck
easily by the hammer. Punches come in many
sizes and shapes to do a variety of jobs.
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TYPESOF PUNC HES
Drift punch
Drive pin punch Prick punch
Center punch
Automatic center punch
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drift punch is a long tapered punch used for
loosening straight pins, tapered pins, rivets
and other small parts being assembled.
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Drive pin punches
are used to set in place or remove straight
and taper pins and some types of small partsrequiring a drive fit. The diameter of thepunch ends are made slightly smaller than
the nominal size so that the punch will not
blind in the hole.
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prick punch
is made of hardened tool steel and ground toa slender point having 30 degrees to 60 degrees
included angle. It is used to mark slightly orindent the intersections of layout lines to locate
hole centers and to provide small center markfor divider points when laying out circles or
spacing dimensions
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center punch
is similar to prick punch in appearance except
for the point which ground to 90 degreesincluded angle. The center punch is used to
enlarge a prick punch mark so a drill can be
started in the exact location.A
center punchmark is deeper and larger than prick punch
mark.
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automatic center punch
makes punch marks of a uniform sizeswithout the used of hammer. The knurled cap
may be turned to control the depth of the punchmark. It is necessary to locate the punch point
and push down.
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Screwdriver
is a hand tool that is designed to turn
screws. The shank is made of steel set into awooden or plastic handle. The blade is shaped
or flattened to fit recesses in the heads of the
screws or bolts. Screwdrivers are made in
many sizes.
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TYPES OF SCREWDRIVERS
� stubby screwdriver
�
heavy duty screwdriver� Philip screw driver
� Jewelers screwdriver
� Plain screwdriver
�
Double ended offset screwdriver
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stubby screwdriver
helps to start screw where the space is
limited.
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heavy d uty scr ewd r iver
is of average length but is made with a heavyblade and square shank. The shape of the shank
permits the use of the wrench to assist in
tightening a screw. Heavy material is used so
that the blade and shank will resist being twistedwhen a wrench is used.
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phili p scr ewd r iver
is specially designed to fit the heads of
philip screws. It differs from otherscrewdrivers in that the end of the blade isfluted instead of flattened. It is made in
several sizes.
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A j eweler s set of scr ewd r iver
is designed for loosening very small
screws, and it is use only some screws of jewellerys.
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d ouble-ended off set scr ewd r iver
is used for turning screws in awkward
place where there is not enough room to usea regular screwdriver.
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plain scr ewd r iver
is that the shank is made of steel set into a
wooden or plastic handle. The blade is shaped or
flattened to fit recesses in the heads of screw or
bolts.It is made in a variety of sizes.
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CLAMPING AND HOLDING DEVICES
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C-CLAMP
AC-clamp is an all-purpose clamp, made inthe shape of letter C. In general use for all kinds
of work, it is made in many sizes.
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BENCH VISE
A bench vise, usually swivel based is the
kind of most favored for general shop work. Itis securely fastened to the bench with bolts.The faces of the jaw are usually lightly
serrated are hardened to ensure a firm grip
on the work. Finished surfaces should beprotected when placed in the vise by usingbrass or copper jaw caps. Tightening the vise
by hammering on the handle is poor practice.
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Bench Vise
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WRENCHES
A wrench is a tool for turning nuts and
bolts. It is usually made of steel. There aremany kinds of wrenches. They may consist of a slot, socket, pins, or movable jaws for
grasping the nut, with the rest of the tool
serving as a handle for applying pressure.
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TYPESOF WRENCHES
Single-ended wrenches
Double ended wrenches
Close end wrench
Adjustable wrench Lever-jaw wrench
Combination wrench
Check-nut wrench
Tool post wrench
Square box wrench
T-handle tap wrench
Adjustable tap wrench
12 point box wrench
T-socket wrench
Offset socket wrench
Pinhook spanner wrench
Adjustable-hook spannerwrench
Pipe wrench
Allen wrench Socket wrench
Torque wrench
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A single-ended wrench is one that is made to fit
the size of nut and bolt.
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A double-ended wrench has two openings, one
at each end of the handle, to fit two different
sizes of nuts and bolt heads
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A close-end wrench is similar to single-ended
wrench, but because it entirely encloses a
nut, there is a little danger of the wrenchslipping on the nut or of the jaws spreading
apart.
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A check-nut wrench is a thin, single ended or
double ended wrench used for turning checks
or jam nut.
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A tool post wrench is a combination box
wrench and open end wrench. The open-end
is straight rather than offset. The square boxend is designed to fit tool post screws and set
screw on the lathes and machine tools.
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A square box wrench is a single head close-end
wrench having a rather short handle. It is
widely used for square head screws.
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A T -handle tap wrench is used to hold and turn
small taps up to about ½ inch. It usually has
two inserted jaws, which can be adjusted tofit the square end of the tap.
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An adjustable tap wrench is a straight type of wrench having a solid V-shaped opening at the
centre.A sliding member, or adjustable jaw,operated by one of the handles makes it possible
to hold taps of various sizes.
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A T -socket wrench made in the form of T. The
hole or socket, in the end is made in variety of
shapes such as square, hexagonal, oroctagonal.
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An offset socket wrench is made of some
variety of sockets as T-socket wrench. It is
designed to be used on nuts requiring greatleverage.
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A pinhook spanner wrench is designed to fit
around the edge of the large round nuts,
which have holes in them to fit the pins of thewrenc
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A pipe wrench is designed with adjustable jaws
that are serrated, making it possible to grip
round pipe and other cylindrical parts.
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An allen wrench is made of hexagonal shaped
stock to fit the holes in the head of set screws
or socket head screws.
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T orque wrenches are used when it is necessary
to know the amount of turning or twisting
force being applied to a nut. The amount of force is usually indicated on dial scale, which
is mounted on the bench handle.
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An adjustable wrench has a movable jaw,
which makes it adjustable to various sizes of
nuts. When using this type of tool, point the jaw in the direction of force applied.
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