I am attempting to validate my choice of stepper motor for my hobby cnc project. It's a vertical CNC able to handle 4X8 panels of plywood. I'm looking for what a woodworker would consider excellent precision (1/64 or better).
I've put together a spreadsheet to determine if my choice of stepper motor is adequate for the machine. I am only trying to calculate the acceleration values for rapids. At this point, I'm convinced my math is incorrect. I am trying to calculate the X axis torque requirements (assuming only 1 stepper, although it will be driven by 2 on either side of the gantry. I think I can simply divide the torque requirements by 2). It's giving me 14170 in/s2 which is clearly insane.
I've attached a spreadsheet with my math. I can't for the life of me figure out where I went wrong but admittedly there are some confusing conversions between metric and imperial, a consequence of my brain melting and buying stuff from china.
I wonder if someone would be able to take a quick look and point out my errors.
The machine is driven by a stepper, through a 3:1 gearbox, then to a rack and pinion (1.5 module, pinion pitch diameter of 30mm at 20 teeth)
Essentially I've picked a desired rapid speed by educated guess (same speed as the AVID CNC pro line with same size steppers) and am trying to determine the maximum acceleration I can achieve with a given stepper holding torque. There is a big assumption made about the stepper torque curve, as they are cheap Chinese steppers with no manual available.
Thanks!
Attachment 502118