Ok, so here's what I've found.

I double checked that the things I've been trying were modeled and sliced correctly.  When I re-assemble the modeled bits, they are a proper circle.

I printed a 25mmx25mmx25mm calibration cube.  X and Y are both about 25.05mm, and Z is 24.43.

When I look at the printed cylinder thing though, it looks like it's probably squashed about a mm or two on each half preventing it from being a proper circle.

Is it possible that your squash is due to the first layer, which we all squash to get good part adhesion to the bed.  A mm would be too much for this, and your z being 24.43 probably needs a little e-step tuning, if the filament is filling in everything properly.

Andrew

I double checked that the things I've been trying were modeled and sliced correctly.  When I re-assemble the modeled bits, they are a proper circle.

I printed a 25mmx25mmx25mm calibration cube.  X and Y are both about 25.05mm, and Z is 24.43.

When I look at the printed cylinder thing though, it looks like it's probably squashed about a mm or two on each half preventing it from being a proper circle.

(2) It's unusual for Z axis to need calibration on the E-steps. I think it'd be a good idea to print something easily measured with calipers (a round object is not ideal.) So like a 50mm tall box mostly hollow infill of course, and then measure how close it is to 50mm.  This might tell you more about your situation.

This recently became apparent for be when I was trying to mate parts together.  The cylinder I was able to print standing up was perfect.. The one I had to cut in half and lay down wasn't.

Thoughts?