View the video tutorial on YouTube: Computerized Lathe Indexer to see how I mounted my stepper motor on the lathe.

The video is a bit old. Now I use a NEMA 23 L-bracket from Interinar with a brass hinge from the hardware store (click on photo to the left for a closer view). I like a spring-loaded mount because it's easy to disconnect the stepper belt for plain turning. You want to disconnect the lathe motor belt when doing ornamental turning so that your stepper doesn't have to turn all the mass of the motor.

The timing belt and the timing belt pulleys are MXL type which are 1/4" width and a pitch of 0.08 inch (i.e. 12.5 teeth per inch). I recommend the use of plastic pulleys because it's easier to enlarge the center hole to fit on the outboard side of your lathe. I also recommend using double flanged pulleys because the belt stays on easier.

My large pulley is 130 teeth, and the small pulley is 20 teeth. For the small pulley, you'll want a 1/4" bore to fit the stepper motor. I bought mine from MSC, but they don't carry the plastic ones any more. Check out Plastic Powerdrive Products as an alternate source.

For the timing belt, McMaster-Carr has a good selection of various lengths. You'll want to mount the stepper motor and pulleys first, then measure for the required length.