Tolerances, stated plainly.

These are typical as-printed figures on small, well supported features. They do not scale up. A large part holds less, and a filled nylon shrinks differently from PLA. Critical dimensions are reviewed per part.

Why holes run looser

Each layer of a hole is a polygon traced by a round nozzle. Inside corners round off and the bead pulls inward as it cools, so holes print slightly small and slightly out of round. Outer walls do not suffer that as much, so they hold tighter.

Designing for fit

• Clearance holes. Allow for the ±0.2 mm. Or tell us the mating part and we size the hole to suit.
• Press fits and bearing seats. Plan on a hole printed undersize and reamed or drilled to size. Tell us the fit class and we will compensate.
• Printed parts that mate. Both parts carry a tolerance. Two features at ±0.1 mm can stack to 0.2 mm.

What moves the number

• Orientation. Dimensions in the print plane are more accurate than ones built up in height.
• Material. Each shrinks differently as it cools. See the materials page.
• Size. Very small holes and thin features are the hardest to hold.

Call out what matters

A part with three critical fits and forty cosmetic ones is easy to plan around. Mark the critical ones on a drawing or name them in the quote notes, and we orient and finish the part to hold them.

If a part does not match the approved geometry and the stated tolerance, we remake it at our cost.