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8/10/2019 Cutting Tools & Tool Holders.pptx
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OBJECTIVES
TO BE ABLE TO IDENTIFY AND KNOW THE PURPOSE OF
THE VARIOUS TOOLBIT ANGLES AND CLEARANCES.
TO BE ABLE TO PREPARE A GRINDER FOR SHARPENING A
GENERAL PURPOSE LATHE TOOLBIT. TO BE ABLE TO GRIND AND SHARPEN A VARIOUS LATHE
TOOLBIT.
TO BE ABLE TO I DENTIFY AND STATE THE PURPOSE OF
THE COMMON LATHE TOOLHOLDRES.
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High Speed Steel(HSS) toolbit
CUTTING TOOLS
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Cement-Carbidelathe toolbit
CUTTING TOOLS
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Toolbitora lathe cutting tool is
generally known by the operationit performs.
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Right cut tool
Left cut tool
Right cut side facing tool
Left cut side facing tool
Curved cutting or round-nose
tool
Knurling tool
Form tool (Radius, Bevel)
Treading tool (External,
internal)
TOOLBIT
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To produce various surfaces, faces and
forms, the cutting edge of the toolbitmust be precisely ground.
The cutting edge must be shaped to the
proper form and then the relieved with
clearance angles to allow the edge to cutinto the metal.
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Pedestal grinder
consist of an electric
motor with a
grinding wheelmounted on each
end of the spindel.
This type of grinding
called offhand
grinding.
GRINDER
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TYPE OF GRINDER
WHEELS
Aluminum oxide are used to grind
carbon and high speed steel (HSS)
toolbits.
Silicon carbide are used to grind
single-pointed cement-carbide cuttingtools.
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GRINDER SAFETY
Always wear approved safety glasses when
operating a grinder.
Always stand to one side of the wheel
when starting a grinder. Never stand in the
line with a grinder wheel.
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GRINDER SAFETY
Allow a new wheel to run for about one
minute before using. If a wheel is going to
break, it will break in the first minute.
Always use a wheel guard which covers at
least one-half of the grinding wheel.
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GRINDER SAFETY
Never run a grinding wheel faster than the
speed recommended on its blotter.
Do not grind on the side of a wheel unlessit is designed for this purpose.
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DRESSING AND TRUING A
WHEEL
Dressingis the process of recondition
the wheel to make cut better.
Truingrefers to shaping a wheel to a
desired shape and to make it grinding
surface run true with it axis.
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TO DRESS AND TRUE A
WHEEL
Adjust the grinder work rest
Wear an approved pair of safety glasses.
Stand to one side of the wheel and then
start the grinder.
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TO DRESS AND TRUE A
WHEEL
Hold the dresser down firmly with its lugs
against the edge of the work rest. Move the dresser across the face of the
wheelin a steady motion for a trial pass.
After each pass, tilt the holder up sligthly toadvance the dresser disks into the wheel.
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TO DRESS AND TRUE A
WHEEL
When the wheel is dressed, stop the
grinder and adjust the work rest to within
1/16in. (1.58 mm) of the wheel face and
tighten securely.
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GRINDING A LATHE TOOLBIT
A lathe tool cuts better if it is provided with
the proper amount of end and side relief.
Too much relief angle (side and end)weakens the toolbit, although it provides a
keener cutting egde.
Too little side or end relief prevents a lathetool from cutting.
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Recommendation factors:
The size and condition of the
lathe
The shape and hardness of theworkpiece
The type of cutting operation
being performes.
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HOW TO GRIND A TOOLBIT?
Hold the toolbit firmly while supporting the
hands on the grinder tool rest.
Tilt the bottom of the toolbit in toward the wheel
and grind the 10side-relief angle and formrequired on the left side of the toolbit.
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HOW TO GRIND A TOOLBIT?
Grind until the side cutting edge is about
in. (12.7mm) long and the point is over
about one-fourth the width of the toolbit.
High speed steel toolbits must be cooled
frequently.
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HOW TO GRIND A TOOLBIT?
Hold the back end of the toolbit lower than the
point and grind the 15end-relief angle on the
right side. At the same time the cutting edge
should form an angle of from 70 to 80
with theside cutting edge.
Hold the toolbit about 45to the axis of the
wheel, tilt the bottom of the toolbit in, and grind
the 14side rake on the top of the toolbit.
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HOW TO GRIND A TOOLBIT?
Grind the side rake the entire length of the side
cutting edge but do not grind the top of the
cutting egde below the top of the toolbit.
Grind a slight radius on the point being sure tokeep the same end and side-relief angles.
Use an oilstone to hone the point and cutting
edge of the toolbit to remove sharp edge,produce a keener cutting edge, and improve its
cutting action.
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A OO O S A
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LATHE TOOLHOLDERS AND
TOOLPOSTS
Method of holding the lathe cutting tool:
In Toolholders, which provide a means of
rigidly holding the cutting tool.
In Toolposts, which provide a means of
holding either a toolholder or a cutting
tool.
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Left-hand offset toolholder is
used to machine work and
cutting from right to left. It is
identified by the letter L.
TOOLHOLDERS
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Straight toolholderit is a
general-purpose toolholderidentified by the letter S.
TOOLHOLDERS
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Right hand offset toolholder
is used for machining work
and cutting from left to right.
Identified by the letter R.
Left and Right hand offset
toolholder accommodate
square toolbits, ranging from
3/16 to in.
TOOLHOLDERS
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Brazed cement Carbide-
tipped toolbits toolholders
are available in five sizes to
accept toolbit shanks from
to 5/8 in, square.
Toolholder hole is parallel to
the base.
TOOLHOLDERS
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Cutting-off or parting tool is
generally used when work is
to be parted off, groove, or
undercut.
1. Solid type toolholders2. Spring type toolholders
CUTTING-OFF TOOLHOLDERS
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A special toolholder with a
cam-shaped cutter ground
to 60is available for
thread cutting,
THREADING TOOLHOLDER
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Boring tool suitable for
heavier work consist of a
boring bar mounted in the
toolholder and a toolbit fitted
on the end of the boring bar.
BORING TOOLHOLDERS
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Heavy-duty boring bar
holder is mounted on the
compound rest and canaccommodate three bars of
different diameters.
BORING TOOLHOLDERS
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Standard (Round) toolpost
provides a means of holding
and adjusting a toolholder ora cutting tool.
TOOLPOSTS
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Turret type toolpost are
designed to hold four cutting
tools, which can be easily
indexed for use as required.
TOOLPOSTS
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Quick change toolpost and
holder are made in different
styles to accommodate
different types of cuttingtools.
TOOLPOSTS