When hole compensation isn't enough

Bambu Lab X Series Bambu Lab X1C
1

I am having trouble with large hole sizes that need to be reasonably round.
I made up a petg test piece with a designed 4.600" inside diameter.
I measured the hole with the probe on my cnc.
I get measurements of 4.5867 on the X and 4.5983 on the Y.
I can live/work with the Y obviously but that X is really killing the project.
I cleaned the carbon x bars again but no joy.

Hole compensation may 1/2 solve the problem but it affects both axis so that isn’t a real fix.
Any thought, tips, tricks on improvements or material choice?

2

Have you retentioned the belts?

3

Been there done that every so often. Belts currently running center on pulleys.
Will redo them again if nothing else pops up to try.

Oh, and I am up to date on firmware, etc and have done the calibration/restart routine.
I tend to run the calibration drill fairly often just because.

4

If you print just a ring with 4.6" inner diameter does it come out closer to size?

5

That is exactly what I did. It’s a ring