Transcript Lathe Accessories

46-1
Lathe Accessories
• Divided into two categories
– Work-holding, -supporting, and –driving devices
• Lathe centers, chucks, faceplates
• Mandrels, steady and follower rests
• Lathe dogs, drive plates
– Cutting-tool-holding devices
• Straight and offset toolholders
• Threading toolholders, boring bars
• Turret-type toolposts
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Lathe Centers
• Work to be turned between centers must
have center hole drilled in each end
– Provides bearing surface
• Support during cutting
• Most common have
solid Morse taper shank
60º centers, steel with carbide tips
• Care to adjust and lubricate occasionally
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Revolving Tailstock Centers
• Replaced solid dead centers for most
machining operations
• Used to support work held in chuck or when
work is being machined between centers
• Contains antifriction bearings which allow
center to revolve with workpiece
– No lubrication required between center and work
• Types: revolving dead center, long point
center, and changeable point center
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Chucks
• Used extensively for holding work for
machining operations
– Work large or unusual shape
• Most commonly used lathe chucks
– Three-jaw universal
– Four-jaw independent
– Collet chuck
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Three-jaw Universal Chuck
• Holds round and hexagonal work
• Grasps work quickly and accurate within
few thousandths/inch
• Three jaws move
simultaneously when
adjusted by chuck wrench
– Caused by scroll plate into
which all three jaws fit
• Two sets of jaw: outside chucking and
inside chucking
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Four-Jaw Independent Chuck
• Used to hold round, square, hexagonal, and
irregularly shaped workpieces
• Has four jaws
– Each can be adjusted independently by chuck
wrench
• Jaws can be reversed to hold work by inside
diameter
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Headstock Spindles
3. Cam-lock spindle nose
•
•
Held by tightening cam-locks using T-wrench
Chuck aligned by taper
on spindle nose
Registration lines on spindle nose
Registration lines on cam-lock
Cam-locks
Cam-lock mating stud on
chuck or faceplate
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46-8
Collet Chuck
• Most accurate chuck
• Used for high-precision work
• Spring collets available to hold round,
square, or hexagon-shaped workpieces
• Each collet has range of only few
thousandths of an inch over or under size
stamped on collet
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Types of Collet Chucks
• Spring-collet chuck
– One form: Handwheel draws collet into tapered
adapter
– Another form: Uses chuck wrench to tighten
collet on workpiece
• Can hold larger work than draw-in type
• Jacobs collet chuck
– Utilizes impact-tightening handwheel to close
collets
– Wider range than spring-collet chuck
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Collet Chuck
|
Special adapter fitted into taper of headstock spindle,
and hollow draw bar having internal thread inserted
in opposite end of headstock spindle. It draws collet
into tapered adapter causing collet to tighten on workpiece.
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46-11
Steadyrest
• Used to support long work held in chuck or
between lathe centers
– Prevent springing
• Located on and aligned by ways of the lathe
• Positioned at any point along lathe bed
• Three jaws tipped with plastic, bronze or
rollers may be adjusted to support any work
diameter with steadyrest capacity
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Follower Rest
• Mounted on saddle
• Travels with carriage to prevent work from
springing up and away from cutting tool
– Cutting tool generally positioned just ahead of
follower rest
• Provide smooth bearing surface for two jaws of
follower rest
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Cutting-Tool-Holding Devices
• Available in three styles
– Left-hand offset
– Right-hand offset
– Straight
• Each has square hole to accommodate
square toolbit held in place by setscrew
– Angle of approximately 15º to 30º to base of
toolholder
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Left-Hand Offset Toolholder
• Offset to the right
• Designed for machining work close to
chuck or faceplate and cutting right to left
• Designated by letter L
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Right-Hand Offset Toolholder
• Offset to the left
• Designed for machining work close to the
tailstock and cutting left to right
– Also for facing operations
• Designated by letter R
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Straight Toolholder
• General-purpose type
• Used for taking cuts in either direction and
for general machining operations
• Designated by letter S
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Carbide Toolholder
• Has square hole parallel to base of
toolholder to accommodate carbide-tipped
toolbits
• Hold toolbit so there is little or no back rake
• Designated by letter C
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Cutting-Off (Parting) Tools
• Used when work must be grooved or
parted off
• Long, thin cutting-off blade locked
securely in toolholder by either cam lock
or locking nut
• Three types of parting toolholders
– Left-hand
– Right-hand
– Straight
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Threading Toolholder
• Designed to hold special form-relieved
thread-cutting tool
• Has accurately ground 60º angle
– Maintained throughout life of tool
• Only top of cutting surface sharpened when
becomes dull
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Compound Rest
Tooling Systems
• Standard, or round, toolpost
– Generally supplied with conventional engine
lathe
– Fits into T-slot of compound rest
– Provides means of holding and adjusting type
of toolholder or cutting tool required
– Concave ring and the wedge or rocker provide
for adjustment of cutting-tool height
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Super Quick-Change Toolpost
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