Extruder stepper motor tuning



  • Hello,

    I'm having issues tuning my extruder stepper motor. For the extruder I'm using a JK42HW34-0334 stepper with these specs:
    Resolution: 200 steps/Rev (with 1.8 °)
    Rated voltage [v]: 12 V
    Consumption current coil: 0,33 A
    Coil resistance 34 Ohms
    The inductance of the winding: 46 mH
    The moment held 2.3 kg*cm (0,22 Nm)
    Conclusions: bipolar (four wire)
    Weight: 200 g

    As visible in the photo, I'm getting some diagonal ribbing on the walls.

    In config I'm using 16 microsteps interpolated to 256, 400mA current.
    Increasing current to 800mA makes the ribbing more pronounced, going down to 300mA makes no difference compared to 400, extrusion issues begin below 300mA.
    Changing microstepping to full 256 without interpolation only increases the frequency of the ribbing.

    What else can I try?

    0_1559136126673_diagonal ribbing.jpg



  • get different stepper motors

    https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors

    General recommendations
    Avoid motors with rated voltage (or product of rated current and phase resistance) > 4V or inductance > 4mH.



  • Thank You for the response.
    I changed the extruder stepper motor to a 42BYGHW609 rated for 2.55V, 1.7A and 2.8mH. I tried 800, 1000 and 1600 mA but the wall quality has not changed.



  • That's a very odd pattern. Given that for each layer, the print head moves around the perimeter it's hard to imagine why it would be the extruder that is causing the issue. Might those lines be made of a series of small dots that coincide with the start and end point of the perimeter I wonder. Do you have "seem aligned" set in the slicer or some other setting? If it's some other setting try "seem aligned".

    Also, a bit more information about your printer might help. Is it a Delta, Cartesian, CoreXY or some other kinemantics? Maybe also give us a bit more information about your other settings - pint speed, temperature etc as well as post your config.g file might help to shed some light.


  • administrators

    Does the horizontal distance between ribs match 1 revolution of the hobbed shaft, or 1 revolution of the extruder stepper motor?



  • @deckingman

    It's a cartesian with the bed moving in Z axis and direct driven hotend moving in XY. 2 Y axis motors, 1 X axis motor.

    Seam is set to optimized but I checked the GCODE viewer and its always in the same place, by that I mean its vertical with this particular model.

    No infill, just 2 perimeters (it looks the same with infill), base speed is 100mm/s with outer wall speed at 40mm/s, lowering speeds does not help.

    @dc42

    The model in the photo has XY dimensions of 40x40mm, horizontal distance between ribs is around 8mm and with 11mm diameter filament gear, 0.2mm layer height, 0.4mm nozzle, I don't believe there is a correlation there. My math might be wrong though.



  • @mildw4ve What extruder is it? Also, can you post pictures of the other faces of that cube.

    Edit. @dc42 might be on to something. It's the circumference of the hobbed bolt that grips the filament which would be important to know. Is that gear clean and are the cuts nice and even all round? Is it a Titan with knackered bearings?



  • This post is deleted!

  • administrators

    @mildw4ve said in Extruder stepper motor tuning:

    The model in the photo has XY dimensions of 40x40mm, horizontal distance between ribs is around 8mm and with 11mm diameter filament gear, 0.2mm layer height, 0.4mm nozzle, I don't believe there is a correlation there. My math might be wrong though.

    Can you post a section of the GCode file showing at least one complete layer (not one of the the first few layers) so that we can see how much extrusion is being done per side of the cube?


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