[image] I’m trying to print this box that has 4mm inset magnets. The holes are 4.15 so it should be a snug fit, but fit. In the full size print , they they don’t. No amount of force will get them in. When I cut it up to get a quick print to test various hole sizes ((small piece on the left), it fi…

Maybe this can help as it is not only about the size. Shape can help too: [image] Perfect Flush Magnet Fit Community Contributions [1] Have you ever had trouble placing magnets in the right spot and figuring out how deep they should go in your printed parts? Installation …

[image] JaxCounters: it fits in 4.15 with ease A drop of super glue is what I normally use in this case.

Measure the holes with a caliper at a few angles to see what it actually is, then adjust your holes to correct it. Maybe it is the X/Y hole compensation or something more complicated.

I know how to correct it if needed. My question is why it behaves differently in the test piece vs the whole box.

There is probably warping happening on the box around the holes, but the small part doesn’t have the same stress

At a guess, a given shrink during cool down is dependant on the total part size. At least to some extent. 2% of 10mm versus 2% of 100mm…

Have you tried measuring the holes that fit vs the holes that don’t? What is the difference?

At 4 mm, it’s a little too small to measure the ID with the calipers I have.

This should be pretty easily do able with basic and cheap calipers. I would suggest getting some that can do this if yours are different for some reason.

Getting a reliable sub millimeter measurement on small holes is actually pretty difficult with a set of linear calipers due to how the measuring points are offset and pointed. For reliable measuring a sent of gauge pins should really be used.

Can't figure out hole size for magnets

Bambu Lab H2 Series Bambu Lab H2C

EnoTheThracian December 31, 2025, 12:27am 2

Maybe this can help as it is not only about the size. Shape can help too: