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

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

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

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

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

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

Cam-lock mating stud on chuck or faceplate Headstock Spindles 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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

Types of Collet Chucks Spring-collet chuck Jacobs 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

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

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

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

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

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

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

Straight Toolholder General-purpose type Used for taking cuts in either direction and for general machining operations Designated by letter S Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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.

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

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

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

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