Is the PEI plate damaged?

U1 Toolchanger U1 Troubleshooting guides
1

Hello,

I tried to print a wristwatch band with TPU for someone. The print didn’t come out great, so I stopped the project and went back to my own projects. The watch band was probably too precise for my U1, I don’t want to spend any more time on it.

Now, after cleaning the plate with soap and water and printing with Basic Snapmaker PLA, I have these little ‘scratches’ in the prints. Only on the bottom of the print, on the PEI plate.

The build plate doesn’t seem to be damaged, but I didn’t have these issues before. I tried it on different places on the plate, and with different toolheads and filaments. Two pieces of black and one piece of green (please see the photos). It’s easier to see on the black prints.
I am using the default settings on the Snapmaker U1.

Do you know why this is happening?

20260821_170709
20260821_1707091920×3410 834 KB

20260821_170714
20260821_1707141920×3410 911 KB

20260821_173525
20260821_1735251920×3410 695 KB

Kind regards, Peter

2

Looks like over extrusion possibly?

3

I have the same issues with PETG:

20260821_175838
20260821_1758381920×3410 1.31 MB

Maybe this topic is the same issue?
I really don’t understand, I haven’t changed anything and I am using the default settings in the slicer.

How can I check the over extrusion?

4

Over extrution, or the calibration is a touch too low.

Watch the first layer print. If you see filament squish out and lift off the bed, your print head is too close to the bed. That’s what it looks like to me.

5

I have done the auto calibration.
What else can I do? I am now printing a default cube from the slicer sizes: 150 x 150 x 0.2 mm and will check how that goes.

I really appreciate your help!

6

Strange that this happened after you tried to print with TPU. First I assume we’re talking tool heads #1 here.

Have you tried a different tool head?

Possible that a small pice of TPU is stuck to the tool head. Park the head where you can get to it, heat to 250c & clean with included wire brush.

7

This is a print created in the slicer. 150 x 150 x 0.2 mm.

20260821_211738
20260821_2117381920×3410 1.06 MB

20260821_211733
20260821_2117331920×3410 1.43 MB

I don’t know what to do next.

8

Have you tried to contact the technical support?

It helps if you test on another spare build plate to see whether the scratches showed up again.

9

It looks like the first layer is too close. Do you perform leveling every time you print?

10

Wouldn’t that cause the first layer offset to be too large instead of too small? :slight_smile: