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 0.4–0.7 mm under the insert’s outer diameter (about 0.4 mm for M2–M3, more for M4–M6) 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.