Print Working ISO Standard "M" Threads

Using the ISO standard as described in the attached ThreadTech diagram, I was able to print very usable screw threads using PLA, at 0.2 line thickness.

The ONE adaptation needed is that I had to increase the diameter of the female thread by 0.8mm. This gave me threads that mated with very little resistance (almost zero). I could probably have safely decreased the diameter difference to 0.6mm. Note that at a diameter difference of 0.4mm, I was not able to screw the nut and bolt together. [See my design notes on how this could be improved.]

I did my experiment using a male effective diameter of 3.4cm with a 3mm thread pitch (P). In ISO terms, this is expressed as M34 x 3.0.

I included a screen shot from Blender which shows the profiles of the male and female threads, with the above mentioned spacing of 0.4mm radius (0.8mm diameter). P=3mm in this example.

An additional design component of working threads is that the mating ends of the thread shafts should be "camphered"