Y-axis shift during print

Sometime approx 25-30% of the way through printing a full plate of multiboard connectors, the Y-axis shifted by more than 1mm. No idea at all why.
Note, part in picture is turned on its side for the photo.

I can see some warping on the corners of your part that would cause the nozzle to encounter more resistance and causing skipped steps.
Could you share a bit more about the material used and also if you clean the build-plate? It might also be helpful to know if you used any type of adhesive.

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Warping not an issue. All pieces were well-adhered to the bed, had to be pried off. Bases are perfectly flat. I’m assuming any warping you see is lens distortion.
PolyTerra Black filament
Yes, plate was washed with soap and water, dried with clean paper towel, not touched with bare skin.
No adhesive used.
Addendum, did another print right after, no issues.

I can clearly see some warping on the edges of the part. Just to be sure, could you make another photo of the part with a flat object like a ruler close to the layers where the shift happened. Warping might not only result in edges being peeled off, it can also result in layers that might be getting higher in some spots (toward tension regions like corners) and building up to failure points where the nozzle gets caught.
This could be because of a flow rate thats set to high or a wrong flow dynamics setting, but are by far not the only causes. (I can see some signs of flow dynamics that are off on the corners of your print. Might be worth to run a calibration with Bambu Studio.)

Good to hear you had success with your second attempt!

I straight-edged (with a real straight edge) both x and Y on a handful of pieces, all were level.

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I mean, I can see the image, and I can see the top and bottom layers for as a reference for image distortions. I can definitely see warping layers. Especially on the left side of the model, right before the layer shifted. No clue how you would check that with a straight-edge.

OK, it’s kinda obvious you’re trying to force a theory at this point.

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Prove me wrong, or give me another point of failure.
If been running through quite some rolls of PolyTerra now and had the same thing happen one or two times.
But whatever, its not my issue… Interesting that you have “No idea at all why” this is happening.

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Shift during prints can come from a few things:

  • Print rods or rails need maintenance

  • Overlapping infill like grid or the part is warping

  • Travel speed too high or acceleration and the stepper driver or motor get too hot then they can skip steps.

  • You can try dropping the travel speed down and acceleration by 10 or 20% and see what happens.

  • You can also look at your preview screen and see what auto Z-hop is doing for the multi plate parts or use the normal z hop on this multi part print with your filament override settings.

My Bambu Lab A1 arrived yesterday and I made 2 prints of paint rack shelves (2 different files) - both of them printed with layers shifted at some point in Y-axis.

Y axis layer shift is just one of the print quality failures my bought the start of this month A1 is now having.

It’s never at the same point in a print, and it’s not grid infill related, or due to warping.

Got to be honest, the short lived “Bambu Experience” was lovely, but a touch too brief for me to be happy about. The machine’s gone from flawless and effortless to as dependable as an Ender 3.

I have had a similar issue printing tall object circa 200mm.
At 150mm up the Y-axis shifted about 1mm.
I am fairly new to this game having the printer since november 2024.
This is my second attempt at this print. The first time it failed due to vibration and parts coming away fromt he base once height of print got to around the 150mm mark.
I redesigned the file adding small connecting sprues between the parts at 50mm height intervals. The actual printed model is as solid as a rock now with the connecting sprues, so I am happy that thats not the source of the problem.
I do notice some rippling developing from 100mm up so I am thinking this is vibration as the desk the printer is sitting on is not 100% rock solid. Something I need to improve (lesson 1).
However, the step on the Y axis is fairly extreme and seems to me like the Y axis drive belt jumped a rib or two.
I did notice that the higher up the print got the noisier the printer got. I am leaning towards this being a vibration issue that threw the belt off a notch.
I am interested in any one elses experiences similar to this and how the y resolved it. It happened about 35 hours into a 56 hour print.!

I don’t seem to be abble to upload images.

It’s because you were a new user and had limited forum functions.

You should be able to upload images now.

Welcome to the forum.

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New A1 printer and random y Axis shift … Sometimes is good and sometimes bad. About 1mm .





OK, I can now upload the images.
I also should have mentioned the weight of the print. At the time the print failed the weight was about 1200g. I think I just pushed the printer too far.
(1) Desk not stable enough.
(2) Print too heavy. vibration + momentum + too heavy = Y axis belt jump and misalignment.

Ya I believe that might be true, too much weight on the bed of a bed slinger printer.

I had opened a case with Bambu Lab Support.
They cam back with some recommendations.
The suggested using the “Height Range Modifer” function.
This allows you to slow the print down (among other parameter changes) for various print height settings.
See attached image.
I then realised my speed setting was 200mm/s for my last print attempt.
I would need to slow it way down but obviously increase print time dramatically for this print.