Testing Tolerances for 3D Printing


When working on more advanced 3d design for printing, it is likely one will end up creating assemblies of parts. For such projects, it’s advantageous to do a small tolerance test to determine the offset required to give the right tolerance/tightness for the project parts which are meant to fit together.

As a rough guide, starting with these dimensions to match your needs would be sensible:

  • Zero Offset – Likely to not fit, but good for pilot holes for drilling
  • 0.1mm Offset – Snug Dead Fit
  • 0.3mm Offset – Rotating/Sliding Fit
  • >0.3mm Offset – Removable Parts, may require fastener

Modelling Tolerance Test Pieces

Depending on your needs, the assembling parts can be quite varied and different designs will need to be tested accordingly. However, as a quick example, let’s look at a simple case where the parts in question are a cylinder/rod piece which needs to go into a peg hole.

Rather than printing a whole part which the joints in question, we can simply do some quite parts to ascertain the offset which works best for us. In this case, let’s use 10.0mm as the baseline and vary the dimensions from there. Do bear in mind that a 0.1mm offset on a circular piece would increase its diameter by 0.2mm.


Testing with the Final 3d Printed Pieces

Once you have these quick pieces 3d modeled out, it would be a simple matter of testing with the physical pieces to find which size combination of the cylinders + pegs would work best for your use case. And it is a quick way to test the components’ fit and get it 3d printed out while you are working on the other sections of your 3d project.

Well, have fun with it and happy 3d printing as always! =)

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