I'm printing a Tower of Pi on my Ender 3, and I woke up to find this near the extruder:

Powder and shavings piled up in front of the extruder

All my attempts to google this led to checking for either a clogged nozzle or the extruder itself stripping the filament, neither of which appears to be the case.

It looks like the upper edge of the filament might be grinding against the intake hole, so I looked into lubrication, but the consensus appears to be "don't".

Has anyone else had this problem? Is there a name for it, and how do I fix it?

  • $\begingroup$ Are you sure that you are feeding the material along the recommended route? It looks like an approach closer to "straight in" would be less likely to erode the inbound filament. $\endgroup$ – Davo May 5 at 18:51
  • $\begingroup$ @Davo The instructions didn't mention a recommended route, but come to think of it I can move the filament spool holder from the top to the side and see if that helps. $\endgroup$ – Stop Being Evil May 5 at 19:22

The shavings come in part from the extruder design: there is no fillet on the pulling in side, the filament goes up in a sharp angle and is dragged over a rather sharp edge. It also brushes against the leadscrew.

To help with the shavings, you should alter the filament path to try and have a flatter angle than the 90°. A simple rod that pushes out the filament to come in at 80° might already reduce the number of shavings.

More might be reduced by opening the entry hole of the filament to have a 1-2 mm phase around it, altering the angle of the edge that the filament runs against to a much lower one and reducing the ability to shave off flakes. I did swap my extruder for an aluminium one, and it has this phase, and since then I have had little to no shavings at that spot anymore.

  • $\begingroup$ Based on OP's description of how the problem came on, and the model (which looks like it has a lot of retraction), this seems like it's probably indeed the problem, but I never saw anything like that in something like 18 months of use of the Ender 3's original extruder. I wonder if something else is going on too. $\endgroup$ – R.. GitHub STOP HELPING ICE May 6 at 0:31
  • $\begingroup$ And the canonical solution for OP's problem is this: thingiverse.com/thing:3052488 $\endgroup$ – R.. GitHub STOP HELPING ICE May 6 at 0:36
  • $\begingroup$ @R..GitHubSTOPHELPINGICE I had those shavings, and the little change of a simple bar pushing out the filament 10 cm on the top and the other extruder all but eliminated them $\endgroup$ – Trish May 6 at 6:48
  • $\begingroup$ Yeah my "canonical" solution might be overengineered, but I really liked it when I was still using the original Creality extruder because it was so bad at gripping filament, and any extra tension in the filament path seemed to cause intermittent extrusion problems. $\endgroup$ – R.. GitHub STOP HELPING ICE May 6 at 23:43
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    $\begingroup$ Yeah, it was only happening with this one print. I'm going to try that roller bearing one though. Thanks for your help, everyone. $\endgroup$ – Stop Being Evil May 28 at 15:12

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