Print Working ISO Standard "M" Threads

cults3d

Using the ISO standard as described in the attached ThreadTech diagram, I successfully printed very usable screw threads using PLA at a line thickness of 0.2 mm. A single adaptation was needed: increasing the diameter of the female thread by 0.8 mm resulted in threads that mated with almost zero resistance. Reducing the diameter difference to 0.6 mm could have been safely achieved, but attempting this with a 0.4 mm gap failed to allow the nut and bolt to screw together. My experiment utilized a male effective diameter of 3.4 cm with a thread pitch (P) of 3 mm, corresponding to M34 x 3.0 in ISO terms. A screenshot from Blender displays the profiles of the male and female threads, featuring the specified spacing of 0.4 mm radius (0.8 mm diameter). In this example, P equals 3 mm. An essential design component for functional threads is ensuring that mating ends of thread shafts are camphered at a 45-degree angle. This involves shaving off the outermost threads with a 45-degree conical surface to make the threads self-centering and align the parts along the same axis, thereby preventing thread stripping. Conclusion: Given the diameter spacing adaptation required with current FDM technology's printing tolerances, achieving functional ISO thread diameters below M8 x 1.0 would be challenging.