Powder Coated Sheet PETG First Layer Thickness
I have a question about calibrating the first layer. I have been using PETG with the Powder Coated sheets with good results. No problems with PETG sticking and good prints. Trying to dial in dimensional tolerances now. When I print .2mm layer height single layer I get .27mm thick layers throughout live adjust z values that provide acceptable prints. When I increase the first layer height to .35mm and print a single layer I get .42-.43mm thickness with calipers. So that is the same extra material with different layer heights.
Before I upgraded to the Powder Coated sheets I was able to get .2mm layer height exactly with the PEI heated bed. Am I just seeing the extra thickness from the material squeezing down into the texture of the Powder Coated sheet. That is what it seems like, but wanted to see if others have the same results.
RE: Powder Coated Sheet PETG First Layer Thickness
To be honest I look at the first layer appearance and when it is good I am happy, I don't start gauging the thickness and worrying about it's variance from the expected value.
If we assume that prusa slicer is correctly estimating the correct amount of filament to extrude to create a 0.2mm thick layer 0.42mm wide using a o.4mm nozzle, and we squirt that through a limited space onto an uneven surface then it is reasonable to expect that the thickness will vary a little from what we were hoping for.
the overall performance of the first layer will effectively average out, the level of unevenness caused by the textured surface, so at high points on the texture, the filament will be thinner and at low points the filament will be thicker. your measuring device is measuring peak to peak on the top and bottom surfaces of the first layer, it is not measuring into the troughs
3D printing is not an exact science. does the perceived extra thickness of the first layer make a huge difference to your final model?
It is comforting to note that the disparity is similar with a different layer height, suggesting that the issue is in fact in the interface with the textured surface.
I would suggest that thermal contraction will give you more problems with overall dimensional accuracy than the first layer texture
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK