Part prints too small, but 3D calibration cube prints perfectly
I have a weird one. I have a part that is printing too small in X Y and Z. Not by much, in absolute terms 0.15-0.4mm, but the part itself is small and is to interact with a non-printed object so the dimensional inaccuracy makes it unusable. The weird part is that when I print a 20mm calibration cube, it's as close as you could expect, 20.00mm+/- 0.05mm. I have done an XYZ calibration (and the mandatory first layer calibration) and belt tensioning but the error remains. The measurements in the modeler (OnShape) and the slicer (Prusaslicer) agree with each other, which points blame at the printer. And I like my printer and hate blaming it for anything. Now, FreeCAD, not so much. But I digress. I have had my Mk3S+ for years and printed hundreds of things and never noticed this problem before. Does this make any sense at all to anybody?
Ultimately, I can scale *this particular part* in the modeler to account for the error and force it to fit, but I would like to understand what is going on first. Because if I can't trust that *some things* I print will not print accurately, this will drive me nuts.
I tried attaching the STL file, but I am not allowed, since I am likely a shifty type, not to be trusted. Or being my first post on a new account. One or the other.
RE: Part prints too small, but 3D calibration cube prints perfectly
As far as STL's Gcode, Movies, .3MF's and most other file formats, We are all Shifty types...
However if you ZIP Compress the files and attach the ZIP File, you suddenly become an upstanding member of the populace...
Jpegs, PNG's and Zips are acceptable.
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
SOLVED: Part prints too small, but 3D calibration cube prints perfectly
OK, I have more data and I think I have solved the issue. After farting around with seeing if thin wall tubes with wall thicknesses that are not an integral of the extrusion width cause the issue (nope), I reprinted a calibration cube. I carefully measured this and it was smaller in the XY planes than expected. When I compared against the first one I printed, by measuring carefully, I was getting similar results. I must have been sloppy with my measurements the first time around, or my calipers are not working consistently. Now knowing (suspecting?) that everything was too small, I checked my PolyLite filament diameter and it was 1.71mm. Ugh. Changed the filament profile to reflect this and reprinted. The resulting 6mmOD/4mmID cylinder with no infill was within 0.05mm of nominal for the OD. The ID is much harder to measure. I am sure I measured this spool earlier and got 1.77mm. I will have to keep an eye on the filament diameter. So problem solved I hope.