1. Drilling Machine Accessories
Unit 39

2. Objectives Identify and use three types of drill-holding devices
Identify and use work-holding devices for drilling
Set up and clamp work properly for drilling

3. Versatility of the Drill Press
Greatly increased by various accessories
Two categories
Tool-holding devices
Used to hold or drive cutting tool
Work-holding devices
Used to clamp or hold workpiece

4. Tool-Holding Devices
Drill press spindle provides means of holding and driving cutting tool
End may be tapered or threaded for mounting drill chuck
Most common
Drill chucks
Drill sleeves
Drill sockets

5. Drill Chucks
Most common devices used for holding straight-shank cutting tools
Most contain three jaws that move simultaneously when outer sleeve turned
Hold straight shank of cutting tool securely
Two common types
Key
Keyless

6. Chucks Hold straight-shank drills Mounted on drill press spindle
Taper
Threads
Held in spindle by self-holding taper in larger machines
Four types of drill chucks
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7. Types of Drill Chucks Key-type Keyless Precision keyless Most common
Three jaws move simultaneously when outer sleeve turned
Tighten with key
Keyless
Chuck loosened or tightened by hand without key
Precision keyless
Holds smaller drills accurately
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8. Types of Drill Chucks Jacobs impact keyless chuck
Hold small or large drills accurately using Rubber-Flex collets
Gripped or released quickly and easily by means of built-in impact device in chuck
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9. Drill Sleeves and Sockets
Used to adapt cutting tool shank to machine spindle if taper on tool is smaller than tapered hole in spindle
Drill Socket
Used when hole in spindle of drill press to small for taper shank of drill
Used also as extension sockets
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10. Drill Drift
Used to remove tapered-shank drills or accessories from drill press spindle
Always place rounded edge up so this edge will bear against round slot in spindle
Use hammer to tap drill drift and loosen tapered drill shank
Use board or piece of masonite to protect table

11. Work-Holding Devices Angle vise Drill vise
Angular adjustment on base to allow operator to drill holes at an angle without tilting table
Drill vise
Used to hold round, square or odd-shaped rectangular, pieces
Bolt vise to table for stability
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12. Work-Holding Devices Contour vise V-blocks Step blocks
Has special movable jaws that automatically adjust to shape of odd-shaped workpiece
V-blocks
Made of cast iron or hardened steel
Used in pairs to support round work for drilling
Step blocks
Used to provide support for outer end of strap clamps
Various sizes and steps

13. Work-Holding Devices Angle plate Drill jigs
L-shaped piece of cast iron or hardened steel machined to accurate 90º
May be bolted or clamped to table
Variety of sizes
Drill jigs
Used in production for drilling holes in large number of identical parts
Eliminate need for laying out a hole location

14. Work-Holding Devices Clamps or straps
Used to fasten work to drill table or an angle plate for drilling
Various sizes
Usually supported at end by step block and bolted to table by T-bolt that fits into table T-slot
Modifications are double- finger and gooseneck clamps
Finger clamp
U-clamp
Straight clamp
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15. Clamping Stresses
Don’t want stresses to cause springing or distortion of workpiece
Clamping pressures should be applied to work, not step block
Step block should be slightly higher than work
Bolt close to work
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16. Clamping Hints Always place bolt close to workpiece
Have packing block slightly higher than work surface being clamped
Insert piece of paper between machine table the workpiece to prevent shifting
Place metal shim between clamp and workpiece
Use sub-base or liner under rough casting
Shim parts that do not lie flat to prevent rocking