Hole dimensions are inaccurate


I made my first 3d printer. I made x, y, z and extruder calibration. The problem is when i print a material which have holes on it, hole diameter is smaller than the original size. What can be the problem? I use repetier host and Slic3r for slicer.


  • That is quite normal. Moving in a circle drags filament a bit near center so it does not land exactly where you think. It also might be a wrong calibartion creating wider extrusions then you think. Or it is a combination of both. For this I make my holes always a bit larger.
  • Hi, the problem occurs also with my printer, now just a hole is not that big a problem, indeed design them a littele bigger and the problem is solved.

    However using existing project, especially things as "impossible gear" constructions always end up all things stuck and "glued" to each other.

    So I think there must be a better way to solve this!

  • My guess is over extrusion.  I've spent a lot of time tweaking mine just right, and when I print holes they are VERY close to the size they're supposed to be.
  • Predefined models are always a problem if they are designed very narrow. If you have a very precise printer you may come away with 0.2mm distance while others need 0.4mm or more to be able to separate. And as @LordFly already pointed out if your extrusion multiplier is too high you also get broader at the borders. And as soon as they touch the designed distance you are lost.
  • The holes are not really printed as circles, but a polygon inscribed within the circle.  This will always give a smaller opening than the circle.
  • Yes, since stl does only contain triangles a hole gets approcimated by a polygon and slicer creates a polygon and printer prints it.
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