jerk and stepper motor stalling

edited August 2016 in Repetier-Firmware
So I have a custom built 3d printer. I'm having some problems with my y axis. It's a leadscrew with a hefty nema23 motor. It should in my opinion be strong enough to drive this axis. But it stalls no matter what I do. The mechanics are fine, it glides fine when I try too move it manually. But when I try to print something it stalls like crazy.

The controller is set to 1/8 microstepping, with a udoo quad and radds 1.5 controlling it.

When I try high jerk setting, above 10 I get stalling. And the same with under 8 jerk.

I'm just wondering if there is a combination of acceleration, top speed, and jerk that is causing this.

I have it running pretty slow at the moment.
With both Y axis acceleration set too 100, jerk at 10. And max speed is 40mm/s. With infill set too 30mm/s. But still it's hopeless ☺️

I'm rebuilding the axis with belt and pulley. But I would love to figure this issue out as it is driving med mad


  • Where does it stall - when starting a move or at higher speeds?
    A known fact is that steppers loose torque at higher speeds. Also if you get too fast (you didn't say how many steps per mm are required) the timings might get unclean. With radds and no delays this limit is quite high. 200khz should be no problem.

    Could the thread mass also be a problem? With M8 threads for z I can only reach 2-5mm/s before motors stall. A felix pro with steeper angle and good ballgearings can be much faster.
  • edited August 2016
    I think its during start it stalls. The leadscrew on my y-axis is quite large. I think it's 12mm diameter. And 5mm per revolution.

    I'm guessing that's quite high thread mass :)

    The steps per mm is 320, so that can't be the problem, my x axis is much much heavier, but with a 20mm per rotation leadscrew. That works perfectly.
  • Agreed that speed is no issue here.

    So question now is if setup is ok with Nema23. Due is so fast that slow drivers can loose steps as high signal is too short and not detected by driver. So you should maybe study what the requirements of your stepper driver are regarding timer and if they deliver the right power for a nema 23. You can increase stepper delays in configuration.h (expert mode in config tool).
  • The data sheet on my driver doesn't say anything about timer, but max pulse frequency is 100khz. They are made for nema23 so power isn't the problem. Maybe I should try increasing the pulse delay. I think I have it at 2 us at the moment
  • 2us is pretty much. The DRV8825 needs 1.7us and the delay comes on top of delay from program execution. But some toshiba drivers need very high signal times at least for direction changes, maybe caused by optocoupler.
  • Hmm, I think I set it to 2us because the repetier fw wizard said so because I got due(udoo quad) but doesn't matter really. I'll just let it be very slow til I change it to belt powered ☺️
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