Gauge does not fit the pod? Getting tolerances right

What if the gauge does not fit the printed pod?

Print the tolerance test ring first: three rings with +0.2, +0.4 and +0.6 mm. The ring the gauge enters without force but without play shows the right allowance. ASA shrinks more than PETG, so always test in the material you print the pod in.

Why printed holes come out tight

FDM printers place the outer perimeter of a hole slightly inward, and materials like ASA shrink as they cool. A printed hole is therefore almost always a bit smaller than designed.

Clearances

Fit PETG per side
sliding 0.20–0.25 mm
snug 0.10–0.15 mm

For gauges the standard is 0.4 mm extra on the diameter.

Checking the fit with the tolerance test ring

  1. Print the test ring in the pod's material (about 15 minutes).
  2. Try the gauge in the +0.2, +0.4 and +0.6 mm rings.
  3. Pick the ring that fits snugly without force.
  4. Print the matching bore version or change the parameter in the STEP file.

FAQ

Can I just sand the pod?

Yes, for a few tenths of a millimetre. For more than 0.3 mm a reprint with more allowance is cleaner.

Updated: 31 October 2026

Matching files