cutting left hand thread

how do you cut left hand threads on the lathe?

basic q i know but not sure.

will be on a clarke cl 430 when i get it up and running.

Most lathes have a tumbler reverse that lets you reverse the direction of the leadscrew (the spindle rotates in the usual direction), or you can add in an extra idler gear to get the same result.

All in all it's easier as the cutter moves away from the headstock making things less stressful!

Neil

Yes, but it's difficult threading to a shoulder without a run "In" groove.

Regards Ian.

You can turn the tool upside down, run the lathe spindle in reverse and use the tumbler gears to run the tool towards the head and up to a shoulder. The usual warning regarding screw on chucks applies with the lathe running in reverse.

Martin

I have a CL430 and a Warco WMT300, so can compare these 'identical' machines.

On neither of them is there a tumbler to reverse the chuck relative to the power feed. On neither of them is there a screw on chuck. So one helpful thing and one worry disposed of from people who know lathes, but unfortunately not these specific ones.

In the belt box, where you put the gears - see fig 14 in the Clarke Manual on page 15, where it says 'gear train', you will find on the Clarke a slotted piece of metal with a straight slot and the curved slot visible in fig 14. The straight slot is where a single shaft for two reduction spur gears can be attached. This is, unfortunately a problem, as you need to put an idler gear between the first or last gear and the reduction pair, which needs a second slot perpendicular to the main straight one. Sorry, not describing it well. The Warco I have has the facility to put in an idler. If you want me to, I can get a photo of each to show the shape difference so you could make a plate that enables an idler to be used.

If I didn't make it clear, at the moment the Clarke cannot cut LH threads. But it can be made to.

Regards,

Richard

Edited By richardandtracy on 07/02/2017 14:17:12

Edited By richardandtracy on 07/02/2017 14:24:03

pics would be great thanks.

I'll add 2 bad ones tomorrow morning. To get better photos, I'll have to take the drive gears off to see the plates, and given there's no power to the shed where the Clarke is at the moment, and I can only get there after dark.. I will try to get it sorted tomorrow evening, but it's not going to be perfect!

Regards

Richard.

The photos are in my album. The yellow box gear train is the Clarke 430, the one with a green box is the Warco. To clarify things a little, I have outlined the gear spider (where hidden by the gears) in white. I hope this shows what you need to be able to cut LH threads.

I was wrong in my first post that the second slot is perpendicular to the first, it isn't, instead it's at about 45 degrees. It is a right old fiddle to get all the gears to mesh with a LH drive idler in there, you need about 6 hands, and there's barely room for 2.

Regards,

Richard.

great cheers will have to work something out.