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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 shank60º 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 whenadjusted by chuck wrench– Caused by scroll plate into

which all three jaws fit• Two sets of jaw: outside chucking and

inside chuckingCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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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

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Registration lines on spindle nose

Registration lines on cam-lockCam-locks

Cam-lock mating stud on chuck or faceplate

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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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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

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• 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

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• 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

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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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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