[RRLedford]

IMO, the best way (without a helicoil or nut insert) to have an axial loaded internally threaded screw hole in 3D printed parts is to just have an undersized pilot hole and use a coarse thread deep V-groove (not machine thread ) screw that can cut its own thread on 1st installation. Some plastic compatible lube my help avoid tearing up the material as screw forms the thread.

This should also allow for best results when multiple cycles of assembly and disassembly will be needed.


Deck screws come to mind, with a well tapered point. Their coarse thread will give deeper engagement with the plastic and put the plastic adjacent to the hole into tension as the screw enlarges the initially undersized pilot hole as it forms the threat rather than cuts material away.

-Dick Ledford