Hello..... My head is spinning trying to figure out the motor tuning settings for the 8mm Metric Acme Lead Screw, for use in Mach 3. Any one out there know the numbers? And an explanation of how you got them? Thanks.
8mm pitch = 8mm per rotation Standard 1.8deg Stepper motor = 200 steps per rotation Stepper driver (for example) 1/8th microstepping 200 full steps x 8 microsteps = 1600 microsteps per rotation 1600 steps / 8mm pitch = 200 steps per mm (for 1/16th microstepping it would be 400st/mm. For 1/4 microstepping it would be 100st/mm)
Thanks for the response. Isn't 8mm the screw diameter? With a 2mm pitch? That would be a different outcome. And the 4 starts needs to be configured into it, and that is where I lose it.
That will get you close, but don't forget you will need to calibrate your machine to get it really accurate. Our leadscrews are formed by rolling the thread profile, not grinding, so there will be tiny inaccuracies in the pitch of the thread. Alex.
at a thoroughly geeky technical level it is possible to calibrate an unknown system. don't know pitch? don't know microsteps? don't know anything else like gearbox ratio? it's ok, the math will still work (-: you can start with steps/mm set to '1' and carefully figure out some reasonable distances to test over (probably need to turn off homing, defnitely need to turn off soft limits), then use that to calibrate, however.... it makes more sense to guess an initial value. 200 for leadscrews 50 for belts. and then do the standard calibration steps, 3 times is usually enough, hand hovering over Estop for the 1st round (-:. HOWTO Calibrate your CNC Machine for MACH3 or GRBL when starting from 1 you have 1mm is one step, this means if you give a distance of 1600 for a 8mm pitch leadscrew on a 200 step per rev motor, as 8x microstepping, the motor will do one revolution.
