Facing, plain and step turning, knurling, taper turning and external thread cutting.
Facing
Making the end of the job flat and square to its axis. The tool moves across the job by the cross-slide, from the centre outward or outside inward.
Plain (straight) turning
Reducing the diameter of the job along its length. The tool moves parallel to the axis by the carriage. Done as rough turning (deep cut, coarse feed) then finish turning (light cut, fine feed).
Step turning
Turning different diameters one after another to form steps (shoulders), measured with a steel rule / vernier from a face.
Chamfering and grooving
Chamfer – beveling the sharp edge (usually 45°). Grooving – making a narrow groove with a form/parting tool.
Knurling
Pressing a pattern (straight or diamond) on the surface with a knurling tool to give a good grip – e.g. handles. Done at low speed with plenty of oil; the job size increases slightly.
Taper turning
Methods: (1) swivelling the compound rest – short, steep tapers; (2) tailstock set-over – long, gentle tapers between centres; (3) taper turning attachment; (4) form tool – very short tapers.
D = big diameter, d = small diameter, L = length of taper
External thread cutting
- A tool ground to the thread form (60° for metric) is set square to the job with a centre gauge.
- The lead screw and half-nut move the carriage one pitch per revolution of the job.
- Change gears / gear box set for the required pitch.
- Several cuts are taken; check with a thread gauge or nut.
Quick Revision
- Facing – end flat; turning – reduce diameter.
- Knurling at low speed: straight or diamond.
- Taper: compound rest, tailstock set-over, attachment, form tool.
- tan α = (D − d)/2L.
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