Drill chuck, sleeve and socket, drift, and the common drilling troubles with their remedies.
Holding the drill
- Drill chuck – three-jaw key chuck that holds straight shank drills (commonly up to 13 mm). Always remove the chuck key before starting the machine.
- Sleeve – used when the taper shank of a drill is smaller than the spindle taper.
- Socket – used when the drill taper is bigger than the spindle taper (extension).
- Drift – tapered flat key to remove taper-shank drills, sleeves and chucks from the spindle.
Taper shanks use the Morse taper (MT 1 to MT 6); it is a self-holding taper.
Holding the job
Machine vice, clamps and bolts, V-block, angle plate, drill jig. Never hold the job by hand on a drilling machine.
Drill troubles and remedies
| Trouble | Cause | Remedy |
|---|---|---|
| Drill breaks | Too much feed, blunt drill, chips clogged in flutes, job loose | Reduce feed, regrind, withdraw drill often, clamp job |
| Oversize hole | Unequal lip lengths or angles, loose spindle | Regrind drill correctly, check machine |
| Rough hole | Blunt drill, no coolant, too much feed | Sharpen, use coolant, reduce feed |
| Outer corners wear / burn (blue colour) | Speed too high | Reduce speed, use coolant |
| Lips chip off | Too much lip clearance or feed | Regrind with correct clearance |
| Drill does not cut | No lip clearance, blunt | Regrind |
Quick Revision
- Straight shank → chuck; taper shank → sleeve/socket; drift removes it.
- Morse taper is self-holding.
- Unequal lips → oversize hole; high speed → burnt corners.
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