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skipping steps? rounding error?

remcohnremcohn
in Motor Control
I have a Zonestar printer with repetier firmware in it, version 0.92.9 and it looks like its skipping some g-codes if the move they make is under 1mm or something. 
 the bottom infill turns into a bunch of V's instead of neat parallel lines. and a circle turns into a kind of pyramid-like shape with steps. 

its very repeatable and remains the same if i rotate the part 90 degrees. my g-code file prints fine on a friends printer and a file that works for him gives the same errors on mine.

Anyone got some clues what this could be?

Thanks a lot, remco

Comments

  • RepetierRepetier
    Don't think it is skipping steps and rounding error. I think it is simply dragging filament with your nozzle. Much depends on correct steps per mm of extruder so you have enough material to stick where it should. Also temperature and material must fit. So a differently calibrated printer with other nozzle and filament can behave completely different on same g-code. That is why slicers have so many options - just to fit the special problems of printers.

    There is also a thing called backlash and if you have that, infill or direction changes can also cause differences. Try printing a circle and see if it comes out round or not.
  • remcohnremcohn
    edited March 2017
    image
    that is the result. print is about 20mm wide, so quite small. but it has very discrete steps. the gcode file renders just fine in repetier-server etc, and prints fine on my friends printer, with the same nozzle diameter and material. 
    its supposed to be a smooth round curve.
  • remcohnremcohn
    the result is 100% repeatable when printing from SD card or via repetier host/server
  • RepetierRepetier
    Looks like a private pic as we can not see it.
  • remcohnremcohn
    hm, looks like picpaste doensnt like deep linking. this should work pic
  • RepetierRepetier
    To me it looks like underextrusion,a lso it is hard to see on the pic. But such broken lines and parts and wide open parts are not normal. You I guess you need to calibrate extruder steps per mm carefully or if that was ok increase extrusion multiplier in your slicer. Also make sure in host flow is 100%. As a test set it 140% and reprint and see if it gets better.
  • remcohnremcohn
    im not talking about the infill area but about the BIG visible stepping. thats not in the gcode.
  • RepetierRepetier
    What is "BIG visible stepping"? I don't know what it should look like so I just can say I see under extrusion as it looks like filled areas are not full and that leads to more problems like the one you described.
  • remcohnremcohn
    like this 
  • RepetierRepetier
    remcohn said:
    like this 
    Ok, that does not look the same. Looks like x motor is very coarse. What steps per mm does it have and does it move smooth if you move slowly or does it look like big step - pause - big step? In that case it is not holding torque correctly (means not holding microsteps) and so it jumps too much. Then it might just need more current from stepper driver.
  • remcohnremcohn
    both X and Y are 80 steps per mm. and it does small moves just fine. can manually step 0.1mm and it comes back perfectly. 
    same for a move of 50mm or at 5mm/sec, perfectly smooth. 
    This is what gave me the idea its skipping gcode lines. 

    I am currently writing down all the configs and pinouts and see if i can compile a fresh firmware from your site instead of trusting the one that came with it. 

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