Why Printed Holes Are Too Small

Document the failure and confirm that it matches this guide: Circular holes print undersized or require drilling despite correct outer dimensions.

Return extreme overrides to a known printer, nozzle, material, and slicer profile so the diagnosis starts from a stable baseline.

Check extrusion width intrudes inward. Measure a calibration part.

Check material shrink. Use hole compensation.

Inspect low polygon resolution. Increase model segment resolution.

Rule out horizontal-hole sag. Reorient or support horizontal holes.

Change only the single setting or hardware condition supported by the evidence, then run a small test that reproduces the original failure.

Compare the test against the target condition, record the successful value, and save it in a printer/material profile before repeating the full print.