Curious if I can get a sanity check off my problem diagnosis (or alternate theories!)

I tried a long print today and wound up with a 1/2 inch layer shift on the x-axis near the end of a long print, taller than most I’ve done, not certainly not the tallest.

It occured on a spool I just opened a few days ago and printed two other ~250g pieces with. I’m very certain that I never lost control of the filament end. My spool in mounted using the stock ender 3 mount on the left side is the gantry and a filament guide arm.

After reading a bit, I’m thinking this was due to the filament on the spool loosening up from a large travel and then binding on itself. Seems the easiest way to fix this might just be to put more space between the spool and the printer so the slack can absorb the shifting without pushing back on the spool and loosening several turns off filament.

I don’t think it’s heat or any general axis binding as the shift only happened at a single layer, at a hight that I’ve been able to print through before, and the motion generally appears smooth when I exercise it.

So… Experimentation will probably prove me right or wrong, but before I sink another day of print time… Does that sound reasonable or am I missing a common problem?

Edit: Solved, see comment by @[email protected] for the actual problem. Many thanks to all who provided their thoughts!

  • Flaky_Fish69
    5•1 year ago

    So… just to clarify, you’ve ruled out loose belts?

    working backwards-the first thing to check is your belt. Assuming the belt is fine, how is your accel and jerk setting? Id assume those are okay-ish out of the box, but it’s worth a look. a fast move coupled with a slightly too-loose (or too-tight…) belt could hurt things.

    From there, I’d check to see if the nozzle was dragging/catching on anything. (look at the failed print part. you might see nozzle marks. or see where it started.) depending on what material you’re printing on, warping could raise the part up high enough to drag the nozzle, causing slipage in the belt. if it got stuck because the part was obstructing the nozzle, then it’d resume when it got high enough to clear it, but with having lost the x position.

    filament unspooling poorly- regardless of what causes it to do so- that would likely have stripped out the filament at the extruder’s hobbed bolt. you can test that by holding the filament from unwinding while it tries to print some. You might also be able to see filament powder/chewed bits around your extruder.

    Edit to add: is this a Bowden rig? A Bowden tube maintains the length (and length of filament inside it,) without regard for the x position, so it would be difficult to see how a stuck reel could cause a layer shift,

    as a side note, you might be able salvage the print by measuring to where the height to where you lost the print, splitting the part at that height and starting a second print there. then, glue the new part on with some coarse sanding and CA glue.

    • StickyOPEnglish
      1•1 year ago

      Thanks for the tips, and the clarification that spool catching can’t cause this sort of issue with a Bowden setup, I missed that nugget of info! I posted in other comments, but I think it was definitely a catch and loose belt. Surprised that the loose belt didn’t cause problems throughout the print, but maybe I’ve just been getting lucky all this time!

      I’m willing to reprint the entire thing for sexy smooth lines. My manual handicraft of sanding, gluing, painting, etc always leaves me disappointed in the final result 😂

      Again, thanks for the help, much appreciated!