We really need to see pics of what you have before any meaningful diagnosis can be made.

Details of how to post pics on this rather odd site software are here **LINK**

New belt/s might be in order anyway on a secondhand machine. They do deteriorate with age and can take a "set" if not used for extended periods.

100 £ aprox can pay an industrial sewing machine motor.

Lathe can then be modified to something like shown and be easier to use.

After some sage advice from another owner. I scrapped the ridiculously complicated belt set up and fitted a 3 phase motor with VFD drive. It finished up like Neils' set up. I would have gone for it,if it had been available at the time Once you have sorted out the drive system. You will then find that the whole cross slide top slide arrangement is rubbish.The tool is about as steady as a stiff jelly. There are mods you can do, the simplest is to dispense with the top slide and use a Gibraltar style tool post. There are lots of mods that can be done to bring the lathe up to a reasonable level of usefulness. Google "Tricking out an Asian 9 x 20" and other similar topics on the 920 lathe.

Don't get me wrong, the lathe can be turned into a useful machine, but it does take a fair amount of work to get there. The Gate's belt can be expensive and you need to know that there are two possible belts x10 and x20 I forget the value of x.. You can get the Gates belts from the US, if you have any US contacts, they are much cheaper there!

Andrew.

It's just a standard gates 5M710 belt, loads on the net such as here

Edited By JasonB on 22/04/2022 11:55:22

+1

Something is wrong with the setup: Far Eastern lathes suffer from indifferent finish rather than a design that's so bad the belts fly off!

I take it this is a secondhand lathe, in which case check everything – the previous owner may have 'been at it', and moved things, or fitted the wrong belt etc etc.

Correctly fitted belts are reliable, but they are sensitive to misalignments, tension, and the belt matching the pulleys.

A few suggestions:

• Wrong Belt
  • Check the V shape of the belt fits into the V shape of the pulley without hitting the bottom. (Belts come in various profiles and dimensions and they aren't interchangeable)
  • Belt should not be too loose (or too tight). Mine are set so the tightened belt can be depressed slightly by pushing it with a thumb.
  • Correct when new, now wrong because it's stretched or badly worn.
• Motor Misaligned. The motor is adjustable right-left and forward-back. The motor pulley must be parallel to the other pulleys, not tilted in any direction. Check with a straight edge. On a small lathe, the adjustment may simply be two bolts and a few washers sitting in oval slots. Fiddly to adjust and vulnerable to twist if the lathe is overloaded by a head-crash or jamb. If the belt is correct, I think a skewed motor is the most likely cause of belt throwing.
• Pulley(s) misaligned. Pulleys should be parallel. It may be possible for them to move on their shafts, so check and correct as necessary. Start with the pulley farthest from the motor, and then align the motor..
• Bent axle(s). Let's hope not! Unlikely, but perhapsone or more of the shafts are bent. Check the pulleys (without the belt fitted), all spin without obvious wobble. Bent shafts, including that on the motor, are caused by something extreme. Head-crash or excessive belt tightening by a gorilla with a big hammer. (Overtightening is also likely to stretch belts and cause rapid wear.)

It's probably something simple.

Dave