Adjusting Screw Threads

Hi - I was working on making a bolt and nut using this tutorial.

When I was using Fusion 360 for similar I was able to make a slight gap between the threads on the bolt and the threads on the nut in order for smooth use of the nut. Without that it is very tight to turn. Any thoughts on that appreciated.


I was thinking about this subject this myself. About the tolerance one would need. If I had the bolt and wanted to simply subtract it from my body, I thought I might increase the scale of a copy of the bolt by a small amount and subtract that. Should work?

If I were revolving and revolve cutting my own threads I would simply use my drawing and create the small gap in my thread’s, male and females profile?

Without understanding the engineering of threads, wouldn’t this work as a stopgap?

Anyone know how threads change for materials like plastic vs metal?

I know pipe threads are different and I know what happens when the Thread dies aren’t set right or are worn. I use to fit/refit fire sprinkler systems in hotels in my dumber days.

@Oregonerd the problem with increasing the scale of a bolt is though you are indeed increasing diametric clearance it messes with your thread pitch or axial position of each thread, becoming a compounding problem the farther you go.

There isn’t a change for threads in material when talking TPI and standard fasteners. Size and pitch is size and pitch regardless of material. There can be a change in connector type based on component compatibility or sealing properties, such as pipe threads. Pipe threads have a specific thread pitch like any other fastener depending on size but are on a taper. 3/4” per foot or 1°47” (same thing) which affectively causes the sealing affect as you tighten.

I figured that would happen without controlling scale independently in the 3 axis.

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Here is a Q&D model of a custom nut and bolt I created. I used a clearance suitable for prototyping via 3D printing.