Heat-set insert

Definition

Heat-set inserts are knurled brass threads pressed into thermoplastic with a soldering iron or press. The pilot hole is typically 0.3–0.5 mm under the insert’s outer diameter so plastic reflows into the knurl. Depth is insert length plus a little clearance so you do not punch through a thin boss. PLA wants a cooler iron than ABS or nylon. Oversized holes spin; undersized holes bulge the boss.

Calculators that use this

• 3D design & tolerances

  Heat-Set Insert Hole Sizing

  Pilot hole diameter, depth and minimum boss OD for M2–M6 knurled brass heat-set inserts. Depth is insert length plus 0.8 mm so you do not punch through a thin boss.

• 3D design & tolerances

  Print-in-Place Tolerance

  Size print-in-place clearance from your printer’s tested dimensional error plus a press, sliding or loose fit. Z uses a 1.4× penalty for layer lines.