P1S - can't home (XY), loud grinding when reaching the poop chute

Bambu Lab P1 Series Troubleshooting
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Hi all, and TIA for your time and any help!

EDIT: here’s a quick video of it homing during self-test

I’ve had my P1S for about half a year, printed for about 230h, went through various filaments (mainly PETG and TPU, but also a bit of PP, ABS). It was working perfectly, and around one month and a half ago I turned it off (unplugged - I wasn’t home). It sits in my office, so neither hot / cold / humid conditions.

Yesterday I plugged it back in, saw there was a firmware update and updated it, then calibrated. During calibration, at the beginning when homing, it would slam into the back (Y axis) and I could hear some very loud grinding noise when it reached the poop chute. I thought it’s strange, but maybe “part of calibration”, so I let it finish. It would also slam (much less hard) on X, right corner (to the front right of the printer).

After calibration, I tried to change filament and still heard the loud grinding when it reached the poop chute, and got HMS 0700-4500-0002-0002 (it wouldn’t cut it, but pointed to a “skipped steps problem”).

I tried to re-calibrate, got the same Y slam and loud grinding, so I stopped it.

I googled around a bit (couldn’t find any topic / video with the same simptoms, but some similar) and ended up cleaning the carbon and steel rods, as well as re-tensioned the belts (unscrew, move head around a bit, bring it back and re-screw).

I re-started calibration and all seemed fine this time, no more slamming / skipping. I was then able to switch filament without any issues (from PETG to TPU).

When I tried to print something (TPU), it would start its homing dance, but again skip steps when going to the poop chute (less loud, but faster grinding) and it would repeat the homing to chute several times, each time further from the left. I stopped it after a few times, when it reached the center (on X, because for Y it would still go all the way to the back) - so didn’t get a chance to receive an error message.

Any ideas on what else to check? Anything I’d need to clean / oil / grease? Should I revert back to the previous firmware?

Tonight I’ll try to re-tension the belts again, calibrate and start the print - this time on video - and I’ll update here.

  • Printer model: P1S, no AMS
  • Slicer settings used: N/A
  • Type of filament used: PETG / TPU
  • Photos that clearly show the problem: would need video, but can’t take one ATM

Thank you in advance for any pointers!
Raz

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Before you revert, try Restore Factory Settings, or whatever the the equivalent is on your printer. It often corrects strange behavior after a firmware update.

3 Likes
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That’s a good idea, I’ll try it - thank you!

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Back from some more testing: I first re-cleaned the rods and re-did the belt tensioning, did a factory reset, and it made the noises during the self-test.

Then I downgraded it to the previous firmware (that was working flawlessly a while ago, before it… sat there doing nothing) and it did the same.

Here’s a quick 10 sec video of that exact moment: https://youtu.be/r7PY_XNaNvk

So I guess we can rule out firmware / software issues, or basic maintenance.

What should I check next?

TIA!

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It is recommended to also check the nozzle. In some situations, if the nozzle is bent, it could get stuck in the purge chute or the nozzle wiper.

Please also share a video showing the complete homing procedure. It seems like the print head is not centred on the middle of the bed.

This shows that there might be a problem in the Y axis homing, where there is debris at the end of the axis. Double check both ends of the Y axis for any debris that could interfere with the homing positioning.

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Once the Y axis movement is correct and the print head is able to move towards the front, the printer should be able to home as expected.

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Thank you for your reply!

I will double-check the nozzle as well, but there wouldn’t be any reason for it to be bent - it was working perfectly fine before I unplugged it about a month and a half ago and it wasn’t touched since.

I’ve also cleaned the Y axis rods (steel ones), but I’ll double check them as well tonight. However, while manually moving the head around during belt tensioning, I could get it to reach all corners / edges.

I’ll try to start a print later today and film the full homing procedure, from above, as I don’t seem to have it on video right now. That 10s excerpt was from a self-test procedure after having reset it to factory defaults, on the previous firmware.

Thank you!

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Sorry to butt in, but did anything work? it looks and sounds like I have the same problem. Loud noise with the extruder going all the way to the back left corner, it missing the poop chute and extruding on the build plate. I’ve tried cleaning everything as well and I don’t see anything that I would think would be causing it. I’ve let it continue trying to print and it goes fine for two layers but then will suddenly move to the back right corner before going back to print but now the print is off and the layers stop lining up. Its almost like it thinks it knows where the extruder is but its off.

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I just came back to say that it turns out I was the source of my own misery: I had placed a temp / humidity sensor in the right / front side of the enclosure (so I could see it from the camera), and although at first tests it seemed not to encumber the movement - it was actually hitting the rods at one point. I took it out and all is fine now.

So check that you don’t have anything blocking movement: turn off your printer and move the toolhead manually to all corners, while also checking to see if it’s not skipping or dragging at any other point.

1 Like
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No dice for me, the only things that inhibit the movement at all is just the motors which of course are where they are supposed to be

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Had almost the exact same problem and it was my own doing. I installed an additional LED light bar and the switch dropped down right in the path of the toolhead. Moved and fixed!

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