Printrbot Simple calibration question: In short:

3D Printing
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Printrbot Simple calibration question: In short: the outside dimensions are too big and the inside dimensions are too small and I’m stumped. Whether I’m printing something 5mm wide or 50mm wide, after measuring it’s always 0.2-0.5 mm too wide. Any hole is 0.2-0.5mm to small.

My height is very accurate - ask for 4mm, and it is 4mm. It’s just the length and width - and they are both out the same amount, and it’s not a percentage, but rather an absolute amount.

This leads me to believe I’m possibly over-extruding on the perimeters. So I made 4 prints of the same item last night (re-slicing each time). And there was no real change.

Print 1 was a base.
Print 2 I changed the Extruded Width / Perimeter setting to 90%. No help.
Print 3 I have dialed back the extruder firmware setting (M92 Exx) a few points which seemed to help so …
Print 4 I dialed it back another point (it now pulls 28mm of filament when asked to pull 30).

But that didn’t seem to help as much as thought. And now it is hard to tell which of the 4 prints are better - ie: nothing really changed. They are all out by the same 0.2-0.5mm.

Thoughts?

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Considering that the @Printrbot Simple nozzle is 0.4mm, the tolerance you have are very good I think.

As for inside dimension, I get about the same. I think it’s the filament swelling as it dries. Therefore I compensate for it in the design.

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Make sure it’s also not the slicer you’re using. Slic3r is somewhat known for terrible dimensions. Use the free version of KISSlicer or Cura to see what results you get as well.