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.
  • i prefer making holes bit larger !!
  • edited March 2020
    i prefer making holes bit larger !!
    no reply..?
  • For bigger holes you need to modify the stl files to have bigger holes. Slicers can shrink xy, but that shrinks not only holes. Also dimension in xz or yz direction depend on layer height. You might just generate a layer or not making it inaccurate. So you need to think of that while designing your models.
  • In PrusaSlic3r u can use the "XY size compensation" in the expert mode. Current on my printer I will use -0.1 mm. This makes the outer perimeters thinner and the holes larger.
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