Prusa Mk4 - Second failed print with the same failure mode
toobnix.org
This is the second time this happens: somehow the motors or the belt slip (not in just one axis) or the Prusa printer loses its origin or something, 3 or 4 layers into this large and long print: al...

This morning I came to work to a perfectly printed set of plates. So I started another instance of the exact same print, went for a swim at the municipal swimming pool nearby, came back to check on it just in case, and it had done the same thing it did on Friday.

This time, nobody was at the office (it’s Sunday) so I know nobody monkeyed with the print. Clearly the plate hasn’t moved. So those hypotheses are out.

The belts look tight - although the teeth feel a bit chewed up, particularly the table belt. But I doubt this is what caused the slip, as it seems to slip randomly in both directions at the same time.

At this point, I’m placing my bet on the print head coming so close to the edges that it hits the limit(s) when it’s unlucky, or it causes the stepper motors’ counters to overflow or something - i.e. it hits a firmware bug. The PrusaSlicer software seems very confident that I can print this close to the edges, and indeed the printer does it, but I wonder if it’s overly optimistic.

So I bunched up all the plates closer to the center of the bed and re-sliced, so the printer never prints less than ¼ inch from any one edge. Let’s see what happens with that.

  • ExtremeDullard@lemmy.sdf.orgOPEnglish
    3·
    6 days ago

    Grid infill is crossing, get a decent blob or buildup and you could have nozzle collision, I personally like gyroid but it is slower.

    I’ve had the extruder collide into blob on solid infills (or perimeters) when the filament was too hot - usually TPU or TPE - but never infill. I’ll give gyroid a spin though.

    prusa has an article for troubleshooting layer shifting

    That’s a great article. Thanks!

    I’ll go check everything tomorrow. The thing is, it’s the first time this happens (well, second time now). The only unusual thing I did compared to previous prints was fill the bed to the brim, right up to the edges as allowed by PrusaSlicer. I’ve corrected that to make sure this isn’t the issue. Other than that, it’s a printer that’s been printing all day every day for a good year and a half. So yeah, it probably needs some TLC at some point…

    • morbidcactus@lemmy.caEnglish
      2·
      6 days ago

      Says a lot that it can run pretty much maintenance free for a year and a half! I only had issues with my mk3s doing daily enclosed abs prints in the summer, the original petg softened and it ended up killing the idler end of the x axis (idler mount deformed suddenly under tension after like… 1-2 months of that). They may not be the fastest or fanciest but they’re easy to service and in my experience pretty reliable, I repacked the linear bearings after a year or so out of precaution when I did a full rebuild, but I don’t expect needing to do that for a long time.

      Here’s another prusa article for infill patterns, the prusa knowledge base is really decent and applicable to a variety of printers, I use my voron a lot but still refer to it.