Heat Inserts and 3D-printing - a guide

Safety Warning: You’re responsible for your own safety. You’ll be working with hot parts and tools that can seriously burn you or others, or set fire to things around you.

Side, top, and bottom view of M3 heat-set inserts

Here is what I personally use:

If that is outside your budget here's some alternatives that works just as good!

Heat Insert set 

A large pair of tweezers are helpful for moving and holding the hot heat-set insert.

Attaching the heat-set insert tip to the soldering iron is easy:

1. Make sure the soldering iron is cold
2. Unscrew the soldering iron’s tip holder
3. Slide out the soldering iron tip
4. Slide in the heat-set insertion tip
5. Screw on the tip holder

Unscrewing the soldering iron tip holder

Removing the soldering iron’s tipInserting the heat-set insertion tip

Screwing the soldering iron cover back on

Once you’ve attached the tip to the soldering iron, heat the iron to a little below the extrusion temperature of the plastic you’re inserting into. For the PETG part I’m using, I set the soldering iron to 240° C (464° F). You want the plastic to melt, but slowly enough for you to control the direction and depth of the heat-set insert.

The soldering iron temperature is set to 464° F (240° C)

I use a thick wooden board as a work surface, to keep from burning anything.

Place the heat-set insert right-side up – that is, with the larger end up – on the wooden board, then push the soldering iron into that heat-set insert.

Wait a short time for the insert to warm to temperature. I don’t have good advice as to how long to wait. Some people don’t wait at all before moving the heat-set insert to the hole.

Pushing the soldering iron into the heat-set insert

Using the large tweezers, keep the heat-set insert on the soldering iron tip while you move the insert and the iron to the hole you want to press the insert into.

Carrying the heat-set insert to the hole

Keeping the solering iron upright – that is, perpendicular to the hole – genty press the insert with the soldering iron as the insert melts into the plastic. Remove the soldering iron as soon as the insert becomes flush with the plastic’s face (the top of the hole).

Gently pressing the hot insert into the hole

A pro tip: Check the insert’s height visually. Don’t check the height by sliding your finger over it…it’s really hot! (don’t ask me how I know)

A few finished test inserts

And that’s it. Let the insert cool and you’re ready to attach the part to your printer.