Maximum motor size for X&Y on core-XY printer



  • I have a Promega (yes, I appreciate the sympathetic crying). The xy motors seem to get rocket hot when trying to print fast. Even at 680mA which is the default current. So, it skips steps.

    Am I right in thinking a motor with more windings will be able to run faster? I'm looking at Moons nema 17 that are quite long any rated at .88Nm torque.

    I don't know what the stock motors are on this machine, but I wouldn't be surprised if they're junk.



  • @gnydick here's the motor

    Moons' NEMA17 Stepper Motor 3D Printer 0.88Nm(125oz-in)1.5A2Phase 1.8 Degree Stepper Motor 62.8mm(2.47in.) 3Stack Smooth Stepper Motor (Stepper Motor Cable00723 Include, Model MS17HDBP4150) https://www.amazon.com/dp/B07G429DL3/ref=cm_sw_r_cp_apa_i_P3r3BbD3CR0QD


  • administrators

    Motors running hot doesn't cause them to skip steps. Things that cause skipped steps include:

    • Motor current too low (which isn't the case if they are getting hot)
    • Mechanical issue causing high friction or stickiness
    • Acceleration set too high in the M201 command, so that the motor can't produce enough torque for the acceleration demanded
    • Jerk set too high in M566
    • Using stealthChop driver mode at high speeds (see the V parameter of the M569 command)
    • Insufficient power supply voltage for the motor inductance and the speed you are trying to run them at. Use the motor EMF calculator at https://reprapfirmware.org/ to check.

    If it's the last one, then changing to lower inductance/higher current motors (and then increasing the motor current) will help. For the drivers on the Maestro I suggest you aim for a rated current around 1.3A.



  • Ok. That all makes sense. I'm also hearing a loud "clack" when the motors engage sometimes. This is something new. Any idea what that may be?

    I do have a nice motor initialization routine with progressively increasing speed to train the stealthchop system. Sorry the terms in using may be wrong, I just know you want to move slowly at first.



  • I'm trying higher current and it doesn't seem to matter. I just keep hearing a 'clank' while it's printing. I thought before they were rocket hot. NOW they're rocket hot at 900mA. Here are my settings.

    M201 X1000 Y1000 Z75 E2000:2000 ; accleration
    M203 X24000 Y24000 Z2400 E5000:5000 ; velocity
    M566 X1200 Y1200 Z40 E2000:2000 ; jerk

    M906 X900 Y900 Z1000 E500:500 I60; Set motor currents (mA) and idle current percentage (dual Z-motors)

    I just keep getting clunks while it's printing. Sometimes they're diagonal, but not at 45, sometimes they're horizontal, and sometimes they're vertical.



  • I was just printing a really slow print and "CLANK", skipped step. I don't know what to do. 😞


  • administrators

    The clank could be the stepper drivers switching from stealthChop to spreadCycle mode. When you send M569 P0 what changeover speed does it report?

    I suggest you try configuring the drivers to run in spreadCycle mode all the time, to determine whether stealthChop is part of the problem.



  • @gnydick Are you sure the "clank" is coming from the motors? Is it all the motors or just one of them?



  • @deckingman @dc42 Turns out it was loose belts that were slipping one tooth at a time.


 

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