Clearance is the gap you leave between two printed parts so they fit together. Every figure below is per side, meaning the gap on each side of the joint. For a pin in a hole, make the hole larger than the pin by twice the figure.
Pick the fit you need
Press fit: pressed or tapped together, holds without glue
Slip fit: goes together by hand and then stays put. Use this for glued joints, snap-fits and alignment pins. A pin that only slides in during assembly is a slip fit
Moving fit: keeps moving in use: hinges, sliders, anything that turns
Printed assembled: moving parts printed already together, in one print
Clearance per side, by technology
FDM (PLA, PETG, ASA, PC-CF)
Press fit: 0.1–0.15mm
Slip fit: 0.2–0.3mm
Moving fit: 0.3–0.4mm
Printed assembled: 0.4–0.5mm, only where no support is needed between the parts
SLA and Industrial SLA
Press fit: 0–0.05mm
Slip fit: 0.125–0.2mm
Moving fit: 0.2–0.3mm
Printed assembled: not recommended
MJF (Nylon PA12, PA11, Glass Filled PA12)
Press fit: 0–0.1mm
Printed assembled: 0.5mm minimum, more on long or enclosed channels so loose powder can get out
FGF
Slip fit: 2.0mm
Moving fit: ask us
Press fit and printed assembled: not recommended
TPU (flexible, printed on FDM)
Stretch fit: make the TPU part 0.1–0.25mm undersize per side so it stretches on
Slip fit: 0.4mm
Moving fit: 0.5mm
Things that change the number
Holes print slightly small on FDM, and small holes do on MJF. On a critical hole, add 0.1mm to the radius or plan to ream it.
Long parts move more. Near the ends of a long MJF or Industrial SLA part, use the top of the range.
TPU grips. It slides poorly against itself and other plastics, which is why its slip and moving fits need more room than rigid FDM.
Test before a production run
These are starting points, not guarantees. For a critical fit or a production run, order a test print of the mating parts first, and tell us which dimensions are critical when you order.
The same table is on our design guidelines page.