Summary

This thing is a method for making ACME flange nuts with perfect threads. It starts with a flange nut that is printed in two halves. The pieces are then put into a vice and clamped on the flat edges. Using a solder rework gun, the leadscrew is heated and the threads are formed.

See instructions for more info.

Instructions

This part is designed for 3/8" ACME screws. The process of making the threads and joining the part goes as follows:

Print the parts in PLA with 100% infill
Clamp the parts lightly onto the leadscrew using a vice. The halves of the flange nut will not clamp down all the way since the plastic must be reformed into threads.
Heat the leadscrew with a solder rework at high temperature until the PLA softens. Carefully apply more pressure with the vice so that the threads are pushed in. Do not heat the PLA directly. You want the leadscrew to be hot, but not the plastic.
Once sufficient threads have been formed, wait for the piece to cool. Now unclamp the whole assembly. The halves will separate and you will be able to inspect the depth of the threads. Put the leadscrew in water to cool it back down to room temp.
Place everything back in the vice. Using the solder rework gun, set the temperature to ~210-230C. Get a piece of PLA filament to use as welding material. Melt the PLA with the heat gun and spread the melted plastic using a flat head screwdriver. Only weld ONE of the seams.
This part is critical. Take everything out of the vice. You should be able to separate the seams just enough that the nut moves easily on the leadscrew. Set the gap exactly how you want it and weld the final seam.

In the pictures, I have used black PLA as the welding material so that you can see what I am doing. This method is not perfect just yet as I have gotten some warping of the flange due to heating the PLA. With a little more effort I think I can make some very functional parts!

Perfect Thread ACME Flange Nuts