Weird behavior with my P1S (help needed)

Bambu Lab P Series Troubleshooting
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Hello everyone,

I need some help here… I have my P1S for about 2 years now and the printer has been nothing short of a work horse.

However, a couple of days ago, I was printing some commissioned parts for a friend and the after the 3rd part (they are the same), I started seeing issues with the first layer, where the nozzle drags over the filament.

Interestingly enough, it is always on the same area of the plate, which I thought would be a dirty plate, although this NEVER happened before with the Cool Plate Supertack as this plate is actually very forgiving. Nevertheless, I took it out, washed with hot water and dish soap, gave it a nice scrub with a blue Scotch sponge, dried it out and put it back. I restarted the print and, sure enough, the issue was there again, same spot.

Second thought was the worn out nozzle, after all, it has been printing for years almost daily. Even though I did not think a stainless steel nozzle would be worn by PLA and PETG, I decided to changed it and finally upgrade it to a hardened one. Again, I made sure to rewash the plate, put it back, reslice the part with the new config accounting for the hardened nozzle only to see the issue again on the exact same spot.

Last but not least, I changed the filament. But the problem remained the same.

If I do not print on the area, the prints come out perfect.

To me, it is starting to look like that, somehow, the gantry alignment is no longer parallel tot he bed, although this should be compensated by the bed leveling.

Has anyone seen a similar behavior? Any ideas on how to fix this?

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Two years, but how many hours ?

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Easily 3000+ hours… I use the printer to support my robotics team as well

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I changed the plate to a Textured PEI. Same problem… For problem is definitely with the bed leveling procedure…

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Have you been performing the recommended maintenance? Are you sure the magnetic bed surface is free of debris? Have you tried doing a machine calibration?

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Yes… Like I said, the issue started suddenly appearing after 3 perfect prints

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20251126_225550
20251126_2255501920×2560 245 KB

Here is the issue… The first layer used to as smooth as it ca be… not even lines could be felt… now, it looks like this c r a p …

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Clean build plate - Check
Try different filament - Check
Verify/replace Nozzle - Check
Run different build plate - Check
Auto Build plate leveling at print start active - ?

Run full initial calibration cycle - ?
Tried manual Bed tramming procedure - ?
XY core Belt tensioning procedure done - ?

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I factory reset the printer and the problem persists.
I worked on the manual tramming, the bed seems leveled according to my bubble level, but the problem still persists.
Belt tensioning, I checked them and they seem ok… but need to check the procedure to make I am not missing anything.
I also opened a ticket with Bambu Lab tech support.

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Hmm there is no bubble level involved in the tramming procedure because the adjustment is for the relation of the xy core to the build plate and not the level of the machine

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I need to retry that procedure… although the bed leveling should compensate that amd, since the bed is leveled, the offset should be constant every where…

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It is unfortunate that 3D printing uses “level” when “parallel to nozzle travel” is meant. Manual tramming is intended to make the nozzle-to-plate distance as constant as possible anywhere on the entire plate, without changes in the z axis. In order to create consistent layers, the plate must be parallel to the plane in which the nozzle tip moves.

Once properly trammed, automatic bed “levelling” will map minor high or low areas of the plate and then add/subtract z height to compensate. Manual tramming ensures that the variations are as small as possible and within the limits of ABL compensation.

“Level” only tells you if the plate is parallel to the earth, not if it is parallel to the x and y axes. Even if the x and y axes are perfectly level to the earth, a common bubble level will not be precise enough to tram the bed.

Use the wiki procedure to tram, “just touching” the nozzle to the plate. I like to place a light behind the nozzle, lower my eye to plate level, and raise the plate until the light in the nozzle-plate gap just winks out. This seems to be more consistent than judging “touch” pressure against the nozzle. A wrench for the adjustment knobs makes fine adjustments much easier.

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There is also a problem with the back knob… it is nowhere close to flush and seems to be fully tightened

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I will be interested to hear what you find is the problem.

What brand of filament do you use? The idea that that filament is undersized. I saw someone mention to try a different filament. I have had that be a problem in the past.
try measuring the filament with calapers.
(there are some clues that this is not the problem.)

There have been several coments about bed “leveling”. ABL (Auto Bed Leveling) should correct for this I am sure there are limits. Leveling is not a good term. it is more making the head movement parallel with the bed. The common term is bed leveling. But a better term that does not use the misleading term is tramming.
Some people mount their printer tilted forward to have the print “fall” off the bed. that is definatly not “Level” but works just fine.

In thinking what else might be causing a problem is maybe there is a break in a wire or loose connection in a particular head position. I would expect this area to grow if you just printed int he good areas. 3000 hrs seams short for this problem to show. You check your use clock on the printer. Last time i checked my printer it was 9000 range. And have not seen this problem.

do you have a way to measure the bed temperature. It is possible that you have a cold spot on your bed. It is not going to be totally consistent. But maybe you will see a pattern. maybe too hot maybe too cold.
bed temperature is my best guess for your problem. I am guessing the bed heater failed in that area making it too cold. The software controls the bed heater based on one spot measurement.

Good luck. Please post what solved the problem.