P1S autoleveling failing problems

Bambu Lab P Series Troubleshooting
1

been fighting this weird intermittant autoleveling failing problem with my P1S since April back and forth with Bambu Support.

What ever fix i apply it works for a few prints then back to not working. I did have two long streches of it being fixed (replacing the bed and adjusting the 3 screws under the bed) but it always comes back and the only thing that seems to temporarily fix it is looseing all 6 bed screws, wiggling the bed and tightening them back up.

Things i have tried/done:

  • loosen and retighten the 6 bed securing screw - this fixes the problem for a few print jobs, its the most reliable temporary fix
  • check if the bed is too close to the excess chute - it is not
  • checked the Z axis bearings - no protrusions
  • checked if the hot end screws are tight - they are
  • replaced the bed - this fixed it for quite a while but the problem came back
  • confirmed there is nothing on the table that can cause additional vibrations
  • checked and slightly adjusted the 3 screws underneath the bed - this fixed it for a bit as well but problem is back, further adjustments make no different
  • checked if there is something interfering with the heat bed cables - there was nothing
  • re-adjusted the z-axis slider - fixed the issue for 3 print jobs then failed auto bed leveling again

i’m getting super frustrated that nothing seems to be a permanent fix for this issue, anyone ran into this before and have you done something different from the above to fix it?

2

How tight is the Z-Axis belt? It doesn’t need to be overly tight. Too tight and it is going to put a lateral load on the shafts.

3

I’ve gone down quite a rabbit hole lately regarding calibrations and came across this guide for manual bed tramming (leveling). Maybe it can help?
I have not had any issues myself (yet), but i did notice one of the 3 bed leveling knobs were set too loosely when i got the printer.

Can you describe the problem a little bit more? Print quality issues? Is automatic bed leveling failing?

4

when adjusting the Z-axis slider i re-adjusted the belt tightness according to the guide. so it should be regularly tight.

5

realized i wasn’t clear, yes autoleveling at the start of a print fails.

follwoed that guide to adjust the three screws under the bed, it worked for a while then issue came back.

6

I wonder if maybe the tolerances for your bed screws are off a little, and vibrations are causing them to ever so slightly back off. Can you mark the screws to see if they move?

7

There is a tensioner spring that that sets the belt tension.
A toothed belt is also called a timing belt and does not rely on tension to keep it in place. You want enough tension via the tension spring to prevent the belt from jumping off the toothed sprocket.