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BUG: Bridging fails when 2nd process has different layer height

Posted: Tue Aug 25, 2020 10:51 am
by richgain
I have been trying to track down why my bridging setting was failing to be used and have managed to reproduce the error.
Process 1 has a layer height of 0.2 mm and needs to bridge over a hole.
Process 2 is used to smooth the top few solid layers by printing with minimal extrusion and a low layer height (aka ironing).

I have discovered that setting the Process 2 layer height to anything different to the Process 1 layer height causes the bridging to be ignored.
Setting the layer heights in the two process to the same value restores the bridging (shown in yellow).

Re: BUG: Bridging fails when 2nd process has different layer height

Posted: Tue Aug 25, 2020 1:23 pm
by parallyze
Would you mind adding a factory file to have a look at this (File -> Save Factory File as...)?
richgain wrote: Process 1 has a layer height of 0.2 mm and needs to bridge over a hole.
Process 2 is used to smooth the top few solid layers by printing with minimal extrusion and a low layer height (aka ironing).
3dbenchy using two processes. P1 stops at 36.8mm using 0.2mm layer height, P2 starts at 36.8mm:

www.aunix.de/tmp/s3d/Benchy-Test.factory (4.5 MB, too big to attach to a post and ZIP is only 300k smaller, still too big...)
I have discovered that setting the Process 2 layer height to anything different to the Process 1 layer height causes the bridging to be ignored.
Setting the layer heights in the two process to the same value restores the bridging (shown in yellow).
No matter what layer height I set P2 to, it won't affect the bridging from P1....
benchy-test1.JPG

Re: BUG: Bridging fails when 2nd process has different layer height

Posted: Tue Aug 25, 2020 6:30 pm
by richgain
Sure. Here you go. The bridging happens on layer 21 when the layer height in Process 2 is 0.200 mm
Try changing the layer height in Process 2 to 0.020 mm and you should find that layer 21 no longer has the correct bridging.
Bridging.JPG
BridgingGone.JPG

Re: BUG: Bridging fails when 2nd process has different layer height

Posted: Wed Aug 26, 2020 10:53 am
by parallyze
richgain wrote: Tue Aug 25, 2020 6:30 pm Try changing the layer height in Process 2 to 0.020 mm and you should find that layer 21 no longer has the correct bridging.
Now that's an interesting one... :D

This is so far away from the switch at 6.2mm it's really interesting it does affect the bridging at all. Starting from layer height 0.04mm the problem disappears again.