I have some OpenBuilds NEMA 17 steppers from the store. The spec sheet says: Max Slewing PPS: 2500 PPS Max Starting PPS: 2500 PPS Step Pulse Time is in micro seconds. There are 1,000,000 microseconds in a second (1/1e-6). So I think that Step Pulse time = 1000000/2500 = 400 microseconds? The default value is 10 microseconds.. So I just want to confirm I'm using the right specs to calculate pulse witdh?
Defaults are fine, that value doesn't do what you think it does Grbl v1.1 Configuration It's more "how long a pulse does your stepper driver need to register a logic 0/1" - stepper driver handles the pulses to the motor (microstepping, sine wave - even does alternating pulses when not even moving)
Thanks, I'll leave it as is, and move on to tuning and fixing other things... Original reason for asking was (playing with axis gearing ratios) at higher speeds F200->F420 I see the stepper skipping depending on the gearing (which changes steps/mm). Was hoping that Step Pulse Time was the "One Ring to rule them all" setting.. Trial and error travel rates are giving me an idea where it starts to fail. Looking at when it starts to skip I'm seeing a limit somewhere between 7700 and 9625 steps per min (128-160 steps per sec). Was hoping for math to be more predictive than "try it till it fails and back off 10%" as that has burned me before
steps per min is a rare one, so mind the change of units to mm/min but for perspective our ACROS, run our NEMA17s on our BlackBox. Belt drive. Default profile (extremely conservative to be beginner friendly) sets XY max Rate at 5000mm/min OpenBuilds-CONTROL/app/js/grbl-settings-defaults.js at master · OpenBuilds/OpenBuilds-CONTROL We also run around 57 steps per mm with the belt setup there OpenBuilds-CONTROL/app/js/grbl-settings-defaults.js at master · OpenBuilds/OpenBuilds-CONTROL That's 5000*57 = 285000 steps per minute...
Turns out my Stepper Drivers or GRBL board are not right.. Now Drving em at 600,000 steps per min smooth as butter with a RAMBO Einsy (TMC21's) running Marlin... Thanks for the numbers to help me figure out normal from broken..
