1. Lathe Accessories
Unit 46

2. Objectives
Identify and state the purpose of the common work-holding and -driving accessories
Identify and state the purpose of the common cutting-tool-holding accessories
Identify and state the purpose of modular and quick-change tooling

3. 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

4. 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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5. 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

6. Microset Adjustable Center
Fits into tailstock spindle
Provides means of aligning lathe centers or producing slight tapers on work machined between centers
Eccentric slide (dovetail) allows center to be adjusted limited amount to each side of center

7. Self-Driving Live Center
Mounted in headstock spindle
Used when entire length of workpiece is being machined in one operation
Chuck or lathe dog could not be used to drive work
Grooves ground around circumference of lathe center point provide drive
Work usually soft material such as aluminum

8. 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

9. 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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10. 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

11. Headstock Spindles
Universal and independent chuck fitted to three types of headstock spindles
Threaded spindle nose
Screws on in a clockwise direction
Tapered spindle nose
Held by lock nut that tightens on chuck
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12. 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
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13. 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

14. 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

15. 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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16. Magnetic Chucks
Used to hold iron or steel parts that are too thin or may be damaged if held in conventional chuck
Fitted to an adapter mounted on headstock spindle
Used only for light cuts and for special grinding applications

17. Faceplates
Used to hold work too large or shaped so it cannot be held in chuck or between centers
Usually equipped with several slots to permit use of bolts to secure work
Angle plate used so axis of workpiece may be aligned with lathe centers
Counterbalance fastened to faceplate when work mounted off center
Prevent imbalance and resultant vibrations

18. 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

19. 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

20. Mandrel
Holds internally machined workpiece between centers so further machining operations are concentric with bore
Several types, but most common
Plain mandrel
Expanding mandrel
Gang mandrel
Stub mandrel

21. Lathe Dogs Drives work machined between centers
Has opening to receive work and setscrew to fasten the dog to work
Tail of dog fits into slot on driveplate and provides drive to workpiece
Made in variety of sizes and types to suit various workpieces

22. Types of Lathe Dogs Standard bent-tail lathe dog
Most commonly used for round workpieces
Available with square-head setscrews of headless setscrews
Straight-tail lathe dog
Driven by stud in driveplate
Used in precision turning
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23. Types of Lathe Dogs Safety clamp lathe dog Clamp lathe dog
Used to hold variety of work
Wide range of adjustment
Clamp lathe dog
Wider range than others
Used on all shapes
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24. 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

25. 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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26. 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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27. 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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28. 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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29. Toolholders for Indexable Carbide Inserts
Held in holder by cam action or clamps
Types available
Conventional
Turret-type
Heavy-duty toolposts

30. 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

31. 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

32. Styles of Boring Toolholders
Held in standard toolpost
Light boring toolholder
Used for small holes and light cuts
Medium boring toolholder
Suitable for heavier cuts
May be held at 45º or 90º to axis of bar
Mounted on compound rest of lathe
Heavy-duty boring bar holder
Three bars of different diameters

33. 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

34. Modular (Quick-Change) Tooling
Initially developed for CNC machine tools to improve accuracy, reduce tool-change time and increase productivity
Benefits realized on conventional lathes with systems designed for these machines
Modular tooling system must be rigid, accurate and have quick-change capabilities
Basic clamping unit or turret can hold variety of cutting tool modules

35. Modular Tooling System
Principal function is to reduce cost of keeping large tool inventory
Tools can be specifically mounted to suit characteristics of workpiece
More common systems available
The Super Quick-Change Toolpost
The Quadra* Index Toolpost
The Super-Six Index Turret
The Vertical Index Turret

36. Super Quick-Change Toolpost
Provides fast, accurate, and reliable method of quickly changing and setting various toolholders for different operations
Locking system has two sliding gibs forced out against toolholder
Handle pulled into lock position
Provides rigid, positive lock with zero backlash
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37. Super Quick-Change Toolpost
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38. Quadr* Index Toolpost
Allows four tools to be mounted on turret at same time
Each tool locked independently
Provides flexibility to use from one to four tools simultaneously
Unique indexing system of turret allows it to be set in 24 positions (every 15º)

39. Super-Six Index Turret
Designed to simplify and increase machining productivity on engine lathes when multi-operation jobs require use of more than one tool
Up to six tools for external and internal machining operations
Allows height adjustment for each tool
Tool changes can be made in less than 1 sec

40. Vertical Index Turret (VIT)
Designed to give highest accuracy, fastest tool change and greatest rigidity of any tool system available for engine lathes
Same concept as indexing turrets on CNC lathes
Can hold up to six or eight tools
Closest to performance of CNC lathes