I'm attempting to configure the "Travel Per Revolution" parameter in Atmel Studio 7. I am using an Openbuilds C-Rail lead screw assembly with 8mm lead, and the reduction pate. Since the pulley ratio for the reduction plate is 1:1, I assumed the travel per revolution would be equal to the lead, which is 8mm. When I used this value, however, the gantry plate only moved about a quarter of an inch. I'm using a Nema 23 (200 steps per revolution with 1/8 microstepping). For the sake of testing, I switched the value to 1.25, and again told it to move 1". It's now much closer, though I'd like to figure out mathematically which value I should be using. Any ideas?
If it's an 8mm 4 start Trapezoidal lead-screw, I would expect it to move 8mm per revolution. Also, your steps per unit (if it means steps per mm) would be 200 I would have thought (until you're ready to do fine calibration).
200*8 = 1600 steps per revolution 8mm per revolution ergo 1600 steps/8mm = 200 steps per mm and then you do a fine calibration because the leadscrews are not exact. math for that at HOWTO Calibrate your CNC Machine for MACH3 or GRBL
