Heat-Set Insert Test Jig

A simple 3D printable test jig for practicing and validating heat-set insert installation in plastic parts. Also features slots for self-tapping inserts and pre-modelled threads in plastic parts.

This jig was designed to mirror the insert-installation demo shown in Accu’s guide to threaded inserts for plastics and 3D printing, where an undersized hole is used, the insert is aligned at the lip, then pressed in with a heat press or soldering iron before being cooled flush with a flat piece of metal. 

The idea is straightforward: give yourself a sacrificial test piece before committing to a final print. It is useful for:

• checking hole sizing before printing production parts

• dialing in soldering iron temperature and technique

• practicing insert alignment so the insert goes in straight

• testing flush fit and finish on common thermoplastics like PLA, PETG, and ABS, which are the materials the guide highlights as suitable for heat-set inserts 

This kind of jig is especially handy when working with brass heat-set inserts, since the goal is to create strong internal threads for repeated assembly and disassembly without damaging the printed part. 

How to use

Print the jig, place the insert just above or slightly inside the undersized hole, apply heat with the correct tip, and press gently until seated. Once installed, cool and level the insert with a flat metal surface so it finishes flush. 

Why print this

A small test jig can save failed parts, wasted inserts, and crooked installs. It is a quick way to tune your process before moving on to enclosures, robot parts, fixtures, or any other print that needs durable threaded fastening. The source guide specifically frames heat-set inserts as a strong reusable option for applications such as robotic assemblies, camera mounts, enclosures, and other high-demand parts.