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

[GeorgeD]

Hi Irving

I'm struggling here on the Lathe,basically I'm having trouble parting-off...the lathe judders and for the life of me can't understand why I'ts proving difficult to part-off?

Last nightI set the gibs as they were a bit loose,today I got some new tooling and blanks,I've tried parting-off at different speeds,the tool is marginally belowthe center...I used the live center to set the tool up.

Stainless Steel bar,had to cut the workpiece of with a grinder :lol:..it ain't funny:cry:

Any pointers as to whats wrong?

[GeorgeD]

Problem solved,it would seem these Lathes struggle to part-off on hard material and the only remedy is a roller bearing change for the naff standard ball bearings
that come standard.

Now I will have to change em,thank god I don't have to turn a bit off the larger spacer on the spindle because this model doesn't have it,only the thinner plastic spacers which are easily grinded down on a table grinder.