Extrusion Multiplier Calibration and actual dimensions of printed parts
I did the extrusion multiplier calibration for my MINI now several times, always using the "precise method". I get now very close to the 450µm thickness - with some systematic deviations on the fours sides of the cube. I thought so far so good... I tested also if the weight of the part that is as specified by Slicer is the same as the actual weight and that is the case. So I thought that I have a proper extrusion going on.
However, when I print parts now, the overall dimensions do not fit and the parts are usually slightly too large. When I print again with 100% flow, everything fits and the dimensions are correct - but I can see signs of underextrusion in the first/top layers.
Was I doing something wrong for the calibration? I measured with a proper micrometer and on multiple places on each surface. I even printed on different positions of the bed... How can it be, that a single wall is "exact" while the overall part then gets too large?
Do I miss some setting in slicer to compensate for something?
RE: Extrusion Multiplier Calibration and actual dimensions of printed parts
You didn't indicate the typical size of your objects and what you consider slightly too large. It's quite possible that you're simply running into the limitations of FDM printing. A tiny error on a 450µm wall that you can'r measure easily can multiply across a 20 cm object and lead to some measurable differences. That's why it's really hard to make snap-fits etc work for everyone as different printers will have different precision. You can try to adjust for that in your design (by designing slightly larger or smaller parts and/or add more tolerances and/or try a material with greater dimensional stability.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...