Clarke Lathe

[FatFreddie]

The key to getting a good finish is stopping the tool deflecting while cutting, there are several ways to ensure this...

All components between the tool tip and the workpiece must be rigid, not rigid as cant move them with your fingers but rigid as in cant move them with a crowbar! Card is a complete no no, even tin can shim needs to be flat, clean with at most three layers and the tool needs to be well clamped down.

Keep cutting forces to a minimum - deflection is proportional to force. Make sure the tool tip is very sharp - use a high power magnifying glass to examine it and sharpen if it looks at all rough or rounded. It can help to put quite a lot of top rake on for finishing but this tends to make the edge fragile so you have to be careful. You can also use a more pointy tool (technical term) but you then need a finer feed.

Depth of cut, depending on the material, a cut the thickness of paper (0.1mm) might be considered a fairly heavy finishing cut ;-)

Coolant will help protect the tool tip and keep it sharp, if you don't want to use a stream of coolant then the Rocol stuff is pretty good.

The replaceable tip tools tend to be relatively blunt as they're designed for production use on heavy duty machines. It's possible to get sharp ones but carbide is prone to chipping so they are fragile (if you stall the lathe and then rotate the workpiece backwards to free it off, you'll more than likely chip a carbide tool) so I'd recommend HSS tools for a lathe this size.

HTH

Mark