Heat-Set Insert Straightener and Flattener

--Now Customizable for Different Metal Discs and Cylinders--

A simple tool for finishing brass heat-set threaded inserts. The tool is made by printing the model and installing a steel disc or cylinder into one end. The model is parametric, allowing customization for a variety of disc and cylinder sizes.

How to Use This Tool

Use a soldering iron to press the threaded insert until it is almost flush with the surface of your plastic part. Then use the metal face of this tool to press the threaded insert fully flush. This straightens and fully seats the insert while also flattening the surrounding plastic for a clean, professional-looking result.

Parts and Assembly

Glue a metal disc or cylinder to or into the end of the tool. The supplied print profile is designed for a 13 mm × 1 mm steel disc from Amazon (here), although you can use other parts you may already have on hand (see Customization below).

I used super glue to attach the disc, but I don't yet know how well it will withstand repeated heating cycles. If it doesn't hold up, I'll try a two-part epoxy instead.

In the supplied print profile, I made the working end of the tool effectively solid by specifying 75 top shell layers. This increases the thermal mass and helps prevent the plastic from overheating.

PETG seems to work well, at least for installing a few inserts at a time. For higher-volume use, you may want to step up to ABS or ABS-GF.

Customization and Other Metal Parts

You can customize this model (using the Customize button) to accommodate different sizes of metal discs or cylinders. One excellent suggestion from the comments is to use a solid stainless steel cylinder. I've also considered using the disc-shaped and cylindrical magnets I already have on hand. I found 10 × 15 mm steel cylindrical dowel pins on Amazon (here) that also appear to be a good option, although I haven't tried them yet.

Customization allows you to specify the depth and diameter of the opening at the end of the tool, to accept any metal disc/cylinder you are using.  You can also customize the overall length of the tool and the thickness of the wall surrounding the disc/cylinder.  If you come up with a good configuration, please post pictures and a link to your metal insert, and feel free to upload your corresponding print profile!