Threads printed directly in plastic rarely hold up
Cutting or printing threads straight into an FDM part works for light, occasional use, but the threads wear quickly and strip under repeated assembly and disassembly. A heat-set insert solves this by melting a metal insert into a slightly undersized hole, giving you a real machine-thread socket for a screw. The install itself is simple in concept but easy to get wrong: too hot or too long a dwell time deforms the boss, too small a pilot hole cracks it, and a crooked insertion never seats straight. This tool builds a preparatory checklist from your insert size and part material rather than assuming one temperature and hole size fits every case.
How the checklist is built
A starting pilot-hole diameter is suggested slightly under the insert's outer diameter, on the logic that the insert needs plastic to grip and melt around, not a hole it drops straight through. Boss wall thickness is checked against a general multiple of the insert's outer diameter, since a thin boss is the most common cause of cracking or later pullout. Tool temperature guidance is given per material family as a starting point, since PLA melts at a meaningfully lower temperature than Nylon and using one blanket setting for every material either scorches a low-temperature part or fails to seat an insert in a high-temperature one.
Worked example
A 4.6 mm outer diameter insert in a PETG part with a 7 mm boss wall (comfortably above the roughly 6.9 mm guideline): the checklist suggests a pilot hole near 4.3 mm, a tool temperature starting point around 220-240 C, and reminds you to install straight down under light pressure and let the boss cool undisturbed, since a rushed install is a common cause of a crooked or loose-feeling insert even when the hardware itself is correct.
Limitations
This is preparatory guidance, not a temperature, hole size, or load-rating claim. Insert manufacturer instructions take precedence over the general figures shown here, since exact geometry and coating vary between brands. Any joint that actually needs to hold a real load should be pull- or torque-tested on a sample boss printed in the same material and settings before you commit the final part.