Summary

I was not happy with the quality of the threads I found in some of the projects with Dremel attachments. So I studied the spec of the BSF 3/4 inch threads and modeled a new nut myself.

I use this now for my own Dremel attachments. I also use it with a Bosch GRO and the the nut really fits perfectly.

The nut has a little cylindrical space inside one side (see left side in picture). This is intended to be the top (pointing to the machine) in your own project. This ensures that the nut can be screwed all the way up.

I made two outer shapes. One is a 22 mm diameter and the other one is a 22 mm hex nut shape. You can use either one, depending on what fits your project better.

Stay tuned for some attachments using this threads...

I printed them in PLA using 0.2 mm layer with 100 mm/S linear advance on the Prusa i3 MK2 and also in 0.15 mm "optimal" setting on a Prusa i3 MK3. Both results very really very good.