Step 8: Install heat set inserts

General process

Temperature: about 280 °C on the soldering iron works for PLA. Lower and slower also works.
A heat set insert tip sized for each insert is easiest. Kits with every size are on Amazon. A single 3 mm tip also works for all of them. It’s slower to heat the big inserts, but you don’t need to swap tips.
A plain tapered soldering iron tip works too, but the insert is less stable and more likely to tip and foul the part.

Let the iron preheat for a few minutes.
Pick up an insert with the tip. On the base plates and cases, you can instead set the inserts in their holes and press down vertically.
Press the insert gently into the hole. Let the heat do the work. Forcing it can deform and ruin the part.
Don’t insert it all the way. Stop about 0.5 mm short.
Finish by pressing the part against a flat surface, or with a flat tool, so the insert sits flush and flat.

Install 7 M3 inserts in each base plate.

Left and right base plates. Lines point to the seven M3 insert holes on each.

Install a 1/4-20 insert in the middle of each back case, and the M5 inserts on the side. The M5 inserts are for screw-in legs.

The bottom of a back case. Yellow lines point to the two M5 inserts and a red line to the 1/4-20 insert.

Insert a square nut into each base plate slot opening, and tip it into position on one side of the slot.