Here are some pictures of a 20 speed poly-V belt drive I am developing for my South Bend Lathe.
This system gives 20 speeds, with each pulley step using the same tension lever setting as the others.
These are the speeds that I measured:(with a stopwatch and rev counter)
Direct high- 1250, 1050, 710, 560, 415
Direct low - 670, 550, 380, 305, 220
Backgear high- 240, 200, 137, 110, 80
Backgear low- 130, 107, 72, 58, 42
These speeds vary a little from the speeds I calculated but gives a good range and splits the original design speeds
Poly-V belt drive installed
The new pulleys were turned from 5" dia. aluminum with the bronze bushings used for the spindle pulley. The gear for the backgear is a stock 16dp 38 tooth gear, modified and pressed on the bushing.
Stay Tuned, Lots more to follow!
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