1. When using MakerFleet, design your holes as .14 mm larger in diameter than what you need. 95% of cases fall within .09mm larger to .20mm larger. For example, if you want a hole to be 2.2mm in diameter, design it to be 2.34mm and it will end anywhere between 2.155mm and 2.255mm.
2. The difference between using PETG and PLA are minimal.
3. Use the table below to determine the size of self-tapping holes.
4. Make sure you export your .stl or .obj files as high resolution.
Self-Tapping Hole Sizes (Imperial)
|Screw Size||Outer Diameter (inches)||Inner Diameter (inches)||Best design for diameter (inches)||Design size in inches||Design size in mm|
Self-Tapping Hole Sizes (Metric)
|Screw Size||Outer Diameter (mm)||Inner Diameter (mm)||Best design for diameter (mm)||Design size in inches||Design size in mm|
A 3D Printed hole often comes out slightly smaller than designed. Companies like 3D Hubs tell you to not rely on the tolerances of the holes because there are so many different manufacturers that you can’t accurately do it. Because we use the same nozzle size, slicer, and stepper motor step size for all of our machines, we should be able to reliably provide our customers with good tolerances
We decided to test sizes using a thingiverse model that we had found online that had already outlined the sizes for us.
We ended up with a table much like the one on the top, with two different materials, PLA and PETG.
However, when we tested our design, we found that we were way off! When we designed holes on our own CAD software, our sizes didn’t work. We looked closer at our holes and realized a major problem:
We then decided to design our own tester (we should’ve done this in the first place, but hopefully our mistake is not yours) and made sure to export it with a high number of triangles:
That gave us a much more accurate representation of the circle and we had much better approximations, resulting in the aforementioned table.
We then decided how could we design self-tapping holes, since that’s the use case for majority of use cases.
Due to the tolerance of 3D Printed parts, we decided we could go from 55-100% percent thread (normalizing on thread length and density). Therefore, we settled at 77.5% thread as a solid mean and built our approximations around that assumption.
We finally tested our theory by printing it out and checking what we had.
If you want to test the screw tester on your own printer (We use a Prusa MK3 with a .4mm nozzle), you can download our screw tester here.
And if you want to test your own 3D Printer’s tolerances, you can download our STL tester here.
- When using MakerFleet, your holes should be around .14 mm larger in diameter.
- The difference between using PETG and PLA are minimal.
- Use the table above to determine the size of self-tapping holes.
- Make sure you export your .stl or .obj files as medium or high resolution.