Stop or jerk during high speed non extruding moves



  • When I start a print from the maintenance station to the first extruding position the move stops shortly or maybe it is jerky. This happens after approximately 200mm (I have to make a high speed movie because it is really almost impossible to see what is happening).

    The speed is 500mm/s and M204 P2000 T6000.

    I user a 20 mm lead ballscrew with 3200 steps per revolution. This gives 20mm/3200=0,0063mm per step. (The maximum speed for 180kHz would then be 1134mm/s.)

    The move for 200mm is then approximately 30000 steps.

    Does anyone have an idea of why this is happening?



  • If you send M122 right after this move, do you see any hiccups?
    Do you have mesh compensation active at this time?
    What is your Z jerk set to?



  • I see what you are getting at 🙂

    1. I will check if there are any hiccups.
    2. Yes, I do. The mesh could fit the stops.
    3. The Z jerk is 0. I set it to zero in an attempt to reduce ringing in the platform from z-hop. Never thought of that it could influence xy-movements.

    I will test to increase the Z jerk. Thank you for the tip!



  • the Z jerk needs to be high enough to allow for the XY motion to proceed smoothly as the Z axis adjusts the height to match the grid. If it's not high enough it will slow down suddenly to give the Z axis time to move. Z jerk of 60mm/min may be enough.

    Lower acceleration on Z may help the z hop problem.


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