Safety on the lathe, holding work between centres with driving dog and catch plate, and chucks.
Safety on the lathe
- Wear goggles; tuck in loose clothing; no gloves, rings or watches.
- Remove the chuck key immediately after use – never leave it in the chuck.
- Stop the machine before measuring, cleaning or changing tools.
- Remove chips with a chip hook or brush, never by hand.
- Keep the tool overhang short and the job tightly held.
- Do not lean on the machine; keep hands away from the rotating chuck.
Holding work between centres
Long jobs that need accurate concentric turning are held between two centres.
- Drill centre holes at both ends with a centre drill (60° cone).
- Live centre in the headstock spindle rotates with the job; dead centre in the tailstock (lubricate it) – or a revolving centre.
- The catch plate (driving plate) is screwed on the spindle nose.
- A driving dog (carrier) is clamped on the job; its tail engages the slot or pin of the catch plate and drives the job.
Chucks
| Chuck | Features |
|---|---|
| 3-jaw self-centring | All jaws move together; quick for round and hexagonal jobs; less accurate centring and grip. |
| 4-jaw independent | Each jaw moves separately; holds square, rectangular and irregular jobs; can be set true (with DTI) or off-centre for eccentric turning; strong grip. |
| Collet chuck | Small, accurate bar work. |
Other holding devices: face plate (irregular jobs), mandrel (jobs with a bore), steady and follower rests (long thin jobs).
Quick Revision
- Remove chuck key at once; no gloves on lathe.
- Between centres: centre holes + catch plate + driving dog.
- 4-jaw chuck: independent jaws, square/irregular/eccentric jobs.
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