Acceleration not working properly at high steps per mm

  • Today I tried to test if high step per mm affect printing in anyway. Usually I use 1000 step per mm (I'm using external stepper drivers that allows me to set any step per rev from 200 to 51200). I set the step per mm to 3200 for my test. However I noticed that the axis stops violently, with some testing I found that acceleration does not work properly.
    I set the acceleration to 100mm/s^2, so it's slow enough to hear the acceleration process. By the sound my stepper motor makes, it seems like when accelerating, the motor only went through two different speeds before reaching the top speed 60mm/s, and when decelerating the motor speed lowered once to a certain speed(sounds like between 30 and 50), and suddenly stops from there. I read in another thread the the duet wifi is able to generate 280khz step pulse for single axis movement. At 60mm/s 3200 step/mm, the pulse rate is only 192khz. I just brought it up in case it's a firmware defect. I'm totally fine if this by design when resource is limited. I don't really need 3200 step/mm, it's just an experiment. I'm using firmware version 1.18.1.

  • Did you also set the jerk values?

  • I'm not sure about other firmware, but for RepRapFirmware when accelerating from 0 or decelerating to 0, the speed does not instantly jump to the jerk value or instantly jump to 0 from the jerk value. Jerk is used to connect two movements without stopping.


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