mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
I have an almost new mk3s with a smooth PEI sheet. I've cleaned both sides with dish soap and acetone. If I print the same model with the same filament on both sides, one side looks perfect, while the other looks terrible on the 1st layer.
Any thoughts on why this would be happening? Is it possible the PEI on one side is just bad?
I've cleaned it well, and still the same results.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
here's a photo of the bad side print:;
https://photos.app.goo.gl/fB867F3JnY2AXNS4A
And the good side:
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
A mystery!
Logic says that one side must be bad (or at least different to the other).
Fingers are remarkably good at detecting surface defects. If you run fingers over the sheet, does one side feel any different to the other?
If you print the same object multiple times on the bad side but move the print to a different location on the bed each time, does the pattern of marks move around too?
Is the pattern of marks always the same?
Is there any damage on the bad side of the sheet (especially at an edge) that could be lifting the sheet ever-so slightly when you use the bad side?
Cheers,
Tim
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
The answer is simple, the pei sheet is slightly different thickness on each side. As the pinda picks up the steel sheet below the pei. You need to calibrate both sides individually.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
@Neophyl. Good point!
My own thinking (until now) has been that a PEI sheet would normally be more or less the same on both sides, assuming good quality control in the production of the PEI material and the correct application of it. I'll do a test on my own PEI sheet to check that out, but it sounds like you have encountered this issue before.
@Oggie - let us know if you find a separate calibration for the 'bad' side helps. I can also highly recommend the Satin sheet - it is my 'go-to' sheet for almost everything.
Cheers,
Tim
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Yeah I have encountered it before 🙂
When you think about it the actual difference between a 'good' first layer and a 'bad' first layer is such a tiny amount, sometimes only a few thousands of a millimetre. While manufacturing tolerances on a lot of things is good nowadays those pei sheets will be made on a roll and then cut up. You get one from the start of a roll and another near the end then the chances are there will be some difference, even if slight. If there are multiple production lines then the machines that are doing that step in the process will also differ slightly. Then there's the glue thickness application onto the sheet.
Add it all up and I'm impressed with how consistent in general things are.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Bu the thickness of the sheet would impact both sides. The overall thickness of the sheet is the same, no matter what side you're printing on. Now, if there's an irregularity of the PEI, then flipping it over would move that irregularity to the other side of the sheet. But my problem is that the bad adhesion is in the middle of the sheet. So the thickness would be the same.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Yes, the sheet is the same overall thickness, but if the two PEI layers have slightly different thicknesses, then the relative height of the steel in the sheet will be a little different depending on which side you use. During Mesh Bed Levelling, the PINDA probe is detecting the steel in the sheet to determine what it thinks the distance to the sheet is. The Z-offset you have dialled-in for the sheet then determines how far above the 'detected' surface the first layer will print.
In the diagram above, if we had dialled in the Z-offset with the green side uppermost, all is good. If we flip the sheet, the steel in the sheet is slightly higher up and the PINDA probe will detect that and compensate for it. The printer will still print at the same Z-offset from the 'detected' surface, but it will now be physically printing slightly higher than the 'real' surface height which is of course the same whichever side of the sheet you use. The result in this case is less adhesion and squish for the first layer.
If the example above is reversed and we calibrate for the red side uppermost, then printing on green would see the printer printing the first layer too low with over-squish or dragging through printed filament.
As Neophly says, we are talking about very small distances making a difference in the outcome.
Hope that helps! Try calibrating your Z-offset for the bad side and see what you get.
Cheers,
Tim
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Tim that’s a very good visual representation for it.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Yes, that makes sense after that explanation. Thanks everyone!
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Happy to help!
I'll post the Z-offset calibrations for the two sides of my own PEI sheet here just for reference - will try and do that over the weekend.
Cheers,
Tim
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
My worry however, is that the 1st layer seems to be fine on either end of the print, but terrible in the middle. If I adjust z any closer, the 1st layer on either end goes bad.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
I also moved the print to a different spot on the bed, and the 1st layer was fine. So there's definitely something wrong in the very middle of the sheet on that one side.
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
Are you using 3x3 or 7x7 bed levelling?
RE: mk3s smooth pei sheet 1st layer is great on one side, terrible on the other after cleaning.
I just calibrated both sides of my Smooth sheet.
The 'A' side needs a -1.165 Z-offset, the 'B' side needs -1.175, meaning the PEI/glue layer is ~10µm thinner on the 'B' side. Personally I'm amazed it is such a small difference for all the reasons Neophyl pointed out. I'm certainly not going to lose sleep over it! 😀
Cheers,
Tim