1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

X axis skipping on wide prints

Discussion in 'Troubleshooting' started by longtemps, Nov 25, 2013.

Thread Status:
Not open for further replies.
  1. longtemps

    longtemps New Member

    Joined:
    Nov 1, 2013
    Messages:
    5
    Likes Received:
    3
    Today, running a print that was about 8 inches wide, every so often after printing a layer, the extruder assembly, moving on the x axis would start printing the next layer offset about 1/8 inch from the last layer. From the accompanying noises, I theorized that when the assembly hit the left most position it caused the x axis drive gear to jump a tooth of the drive belt.

    Going into the printer settings, I looked at the speed settings and found the speed "when not printing" set to 130 mm/sec. I had never changed the default settings, I have found no official recommendation from Robo 3D. I think either this is too fast when the x axis gets any serious momentum or my belts are undertensioned. I don't see any simple way to adjust the belts, so I ask for suggestions.

    I will try a slower speed setting, for the non-printing motions. I was going to try 60 mm/sec. Ideas?
     
    #1 longtemps, Nov 25, 2013
  2. tesseract

    tesseract Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    1,924
    Likes Received:
    533
    Yes it is related to the belt it may be too loose I need to see a picture but mine were simply connected via loops with tie wraps to the extruder assembly and if this is the case cut the zip tie move the loop in teh belt tighter by a few teeth which will force the tie wrap to end up being a little larger but then it can be cinched down to tighten it.

    The belt should have a definite twang to it if plucked like a guitar.
     
    #2 tesseract, Nov 25, 2013
  3. tesseract

    tesseract Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    1,924
    Likes Received:
    533
    on a side note no real experience to this my self but the source of it is very credible, in addition to the above you can try inserting a half twist in he belt so the the smooth side of the belt goes around the smooth pulley and then allow it to reorient it self correctly so that that the teeth interact with the gear properly but keep in mind this may be a fix to a problem you do not have and possible never will. The thought process was that the teeth contact the smooth pulley could induce a vibration lowering the quality of your prints.
     
    #3 tesseract, Nov 25, 2013
  4. longtemps

    longtemps New Member

    Joined:
    Nov 1, 2013
    Messages:
    5
    Likes Received:
    3
    My belts attach the same way you describe, I will check for the right twang. This and a z axis zero switch that was apparently installed backwards makes me wonder if QC is quite up to snuff on China-assembled machines.

    Still wondering about the motor speed. For the sake of issues like this and parts longevity in general, I think some sort of programmed-in terminal deceleration when these long non-printing extruder traverses occur would be beneficial.
     
    #4 longtemps, Nov 25, 2013
  5. tesseract

    tesseract Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    1,924
    Likes Received:
    533
    I was wondering the same about the QC
    My travel time is actually faster at 140 but I have had no problem.
     
    #5 tesseract, Nov 25, 2013
  6. longtemps

    longtemps New Member

    Joined:
    Nov 1, 2013
    Messages:
    5
    Likes Received:
    3
    I did check my x axis belt and found it pretty tight, a dull twang, though I may try to tighten it a tooth or two - once I acquire some tiny zip ties.

    The abilty to change tension by having an adjustment, moving the free wheeling pulley might be a worthwhile mod.

    Your idea of twisting the belt so that the smooth side contacts that smooth pulley is interesting. In the interest of thoroughness, I wonder if doing that would introduce torsional forces which might be as bad to print quality ;)
     
    #6 longtemps, Nov 26, 2013
Thread Status:
Not open for further replies.

Share This Page