Standard belt is, I think, nylon reinforced PU about 1 mm thick. I got mine from local bearing and transmission supplier ages ago at what seemed a reasonable price for made to order. memory says under £10.

Poly vee seems to work fine Vee side down on flat belt pulleys with a very effective drive. Possibly too effective for a grinding set up where best practice is said to be to run things slack enough that if things hang up the belt slips rather than the wheel being damaged or exploded (yikes!).

I found getting the new belt to run true with the standard motor mount set-up of four short pivoting links a nightmare. I modified my set up to have a something closer to simple pivot set-up by fixing the angles of the lower arms and replacing the slot with three 11/32″ holes at 7/16″ spacing. The slot in the top arms allows a bit of twist if needed to get the motor and spindle shafts aligned.

Much easier to set up.

PM me for PDF format drawing if needed.

Clive

Have you tried Tony?
https://store.lathes.co.uk/parts/drive-belts/betalon-multiply-flat-belting?v=70

Bill

The one fitted to mine when I bought it was a 1040x25mm PU11.

I bought a replacement recently from http://www.gasboosterbelts.co.uk for about £22

Clem.