Posts for the month of September 2023

Heat-set threaded insert tooling box lid

I recently discovered heat-set threaded inserts. These little bits of brass provide a way to use bolts in 3D-printed plastic parts.

The idea is that you create a plastic part with a slightly-undersized hole where the insert will go, and then using a soldering iron with a specialized tip, you heat the insert, which softens the plastic enough that you can press it into the part. Once the plastic cools, the insert is firmly embedded in the part. The inserts have internal threads which a machine screw / bolt can be screwed into. They have sharp teeth features at opposing angles on the outside, so they remain firmly embedded in the part and can't themselves unscrew.

I bought a set of soldering iron tips for this purpose from Virtjoule (via Amazon). The set of brass tips came in a plastic tray which had obviously been 3D-printed.


But there was no lid for the tray. So I threw together a 3D model of a lid for it (OpenSCAD, STL)


and printed it in "transparent" PLA.

lid-bottom.jpg lid-top.jpg

That fits nicely and helps to keep the set of tips together:

box-open.jpg lid-installed.jpg

Being able to quickly create a lid for a box is not something I had anticipated doing with a 3D printer, but in retrospect, it's an amazingly obvious application.

And then there's the intriguing aspect that it's useful to a business creating packaging for a specialty product. In this case, the US-based company is in a business where they are applying 3D-printed parts, and are selling a tool they themselves created and use. So they've found an additional use of infrastructure they already had, and a market for a product they had created for their own use. I think that's really neat.