[difalkner]

Ok, found it!!! At least, my tests are now working as designed. I'll try some more complex shapes later.

Here's what I found - I recall reading somewhere that there's a difference between 2D and 3D Contour in Fusion 360 and that 3D is more a finishing profile. But 2D works for what I have needed about 99% of the time and that's what I use. Plus, you can have tabs in 2D but not 3D. I'm not certain where I read/heard that but I couldn't find this again in a quick search so I'll look later. Backlash has been discussed amongst the folks I queried on this so I tested that, as well. It was very minor - 0.001" to 0.002".

Inlay - For the inlay piece I used 2D Contour and my standard climb cut with 0.005" Radial Stock to Leave for the rough pass followed by 2D Contour conventional cut to remove the final 0.005". The inlays, while slightly off, have not been the issue; the pockets were.

Pocket - I created a profile for 2D Pocket climb cut to clear the inlay pockets with Stock to Leave set to 0.005" Radial. I followed that with a 3D Contour conventional cut and no Stock to Leave plus selected Repeat Finishing Pass to clean up the sidewall. This makes the cutter go around the sidewall twice, so even if the 0.005" clean-up pass had any deflection the second pass around should take care of that.

The pockets now measure what I have specified in F360, or as close as I am able to measure. The important thing is that now the inlay pieces fit with no problem. I even placed my 1" round gauge bar in the 1" pocket and it fit (snug, but it fit).

1" gauge bar in pocket -
Attachment 435744

Testing backlash -
Attachment 435746

Fusion 360 measurement for random double curve I drew for test -
Attachment 435748

Actual measurement -
Attachment 435750

All pieces fit as needed, no forcing, not a sloppy fit, just right for glue -
Attachment 435752

Thanks to all for your help and suggestions! These are just test files but I certainly don't mind sharing them if you want to dive into the settings.
David

[MARV]

David, great to hear that you've resolved the issue. No doubt frustrating along the way. I haven't gotten into Fusion yet, but expect to soon. What prompted you to use a 3D toolpath to mill what would normally be thought of as needing a 2D operation? Thanks for sharing,

Marv