Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Strictly speaking it’s not a flat belt like the old time leather belts.
It’s meant to be a reasonable approximation in a readily available, very good material.

Meant as a non stretch timing belt for such things as copying machines, the belt is fabric reinforced rubber, much like a car tire. It’s flat on top, with teeth like a gear on the bottom.  The one I’m using is 6mm wide, and 1.5mm total thickness.
Though designed as a timing belt, to run on sprocket pulleys reminiscent of miniature dragster supercharger drive, it runs very nicely on wooden pulleys crowned as if for a flat leather. 

Since writing this post, I’ve built a little splicing jig that is in essence a miter box for a single edge razor blade, with a section of toothed timing rack in the bottom of the miter box, so accurate splicing can be achieved.  After bandaging the top with Mylar glued with CA, im sewing them with a 2-0 silk suture in the manner of the staples used on leather belts. The key turned out to be the miter box and the Mylar, a no stretch positioning medium to insure the suture line ends up straight and even.