Hi Mark
I've escaped from hospital and had a look at mine as promised. There is a part missing on your handle assembly.
First here are pics corresponding to yours, of the handle wound clockwise and anticlockwise. There is virtually no backlash. And note that what backlash there is is nothing to do with wear on the leadscrew or nut. It is adjustment of the handle assembly.
Removing the end screw allows you to see the mechanism. The arrowed component, a spacer, is missing on yours.
It is not a thrust bearing, just a spacer, totally pointless to make this a bearing. Its purpose is precisely to adjust the backlash in this drive, and allow the graduated scale to be set easily. If too thin (as yours is, being zero!) it gives backlash in the drive. If too thick, it will clamp up too strongly on the knurled component above, which contains a friction clutch allowing the scale to be rotated (to set to zero, for example) without turning the leadscrew, and will not allow you this useful technique. So the thickness has to be accurate. I measured mine at 1.80 mm thick, but yours may be slightly different. ID is 11 mm, OD 19.5 but you obviously need to check this on yours. Looks like the first job when the lathe is set up!
This is the part you need to make, along with the key just in case that is missing. I think the stepped form is deliberate.
Any wear in the nut/screw is additional to this setting backlash. While the above method of making nuts is useful, in my lathe the main wear is on the central region of the leadscrew, not the nut. And the nut itself is an odd external shape, with wings to fit neatly in the housing, so a plain cylinder nut will not do. The thread, from memory, is 12 mm x 1 mm square, but I'd need to check that. They are available fairly cheaply.
Hope this helps
Keith
I've escaped from hospital and had a look at mine as promised. There is a part missing on your handle assembly.
First here are pics corresponding to yours, of the handle wound clockwise and anticlockwise. There is virtually no backlash. And note that what backlash there is is nothing to do with wear on the leadscrew or nut. It is adjustment of the handle assembly.
Removing the end screw allows you to see the mechanism. The arrowed component, a spacer, is missing on yours.
It is not a thrust bearing, just a spacer, totally pointless to make this a bearing. Its purpose is precisely to adjust the backlash in this drive, and allow the graduated scale to be set easily. If too thin (as yours is, being zero!) it gives backlash in the drive. If too thick, it will clamp up too strongly on the knurled component above, which contains a friction clutch allowing the scale to be rotated (to set to zero, for example) without turning the leadscrew, and will not allow you this useful technique. So the thickness has to be accurate. I measured mine at 1.80 mm thick, but yours may be slightly different. ID is 11 mm, OD 19.5 but you obviously need to check this on yours. Looks like the first job when the lathe is set up!
This is the part you need to make, along with the key just in case that is missing. I think the stepped form is deliberate.
Any wear in the nut/screw is additional to this setting backlash. While the above method of making nuts is useful, in my lathe the main wear is on the central region of the leadscrew, not the nut. And the nut itself is an odd external shape, with wings to fit neatly in the housing, so a plain cylinder nut will not do. The thread, from memory, is 12 mm x 1 mm square, but I'd need to check that. They are available fairly cheaply.
Hope this helps
Keith
