I designed a M8 screw on Fusion 360. It has an hexagonal head with 12mm between the parallel sides. When printing with X1C, the hexagonal head comes out with 11.95 - 12.05 mm which is really good, but the screw diameter is 7.20 mm (should be 7.86 mm). I tried to play with X-Y compensation but it altered the hexagonal head dimension. Then I split the head and the screw apart, but Bambu Studio does not allow to set individual X-Y compensation for each part. Any suggestions on how to improve the screw diameter printing accuracy? Thanks,
Filament: ABS but similar behaviour with PLA
Nozzle: 0.4
Speed: 50 mm/s for everything
Layer height: 0.1 mm
Wall order: Outer/Inner/Infill and infill/inner/outer with no significant change
Wall generator: Arachne
Wall loops: 3
Sparse infill 10% Gyroid
File type: STEP
Bambu Studio 1.7.0 (same thing with previous versions)
It’s likely quantization error. The edges of your threads taper to a point, I’d bet. The slicer can’t print the small scale features, so you don’t get the entire thread diameter. If you made the thread cross section a trapezoid instead of a triangle, so the outer edge of the thread had a small flat rather than a tapered point, this problem would probably go away.
Of course, if your threads don’t taper to a point, my assumptions are wrong. But the fact that the head prints correctly says the printer’s calibration is close, so the threads should be close, too. The only reason I can think of for them not being close is that there is something about the geometry the printer can’t print. That part gets skipped by the slicer and your threads come out too small dimensionally.
I would just scale up the diameter of the threads to correct for the error.
Hi @RocketSled,
Thanks for the insight! You hit the nail. Instead of scaling up my design, I changed my printer settings to acomodate the fine details:
From:
Layer height: 0.2 mm
Outer Wall: 0.42 mm
Inner Wall: 0.45 mm
To:
Layer height: 0.08 mm
Outer Wall: 0.20 mm
Inner Wall: 0.20 mm
That provided me a print within a good tolerance to the original design.
Renan
Note: I did try a few other combinations, but the one that provided me an acceptable printing time X quality it is the one I reported above.
Don’t forget to take into account for shrinking of your material. ABS will shrink around 0.7 to 1.6% when it cools. I’m not sure if the latest Bambu Studio already includes an option for adding shrinkage to your custom material, but OrcaSlicer does.
