Tip for removing bottle thread

[Mike C]

This may have been mentioned previously, but anyhow.
I've been using a 19mm or 3/4" drum sander to hold the bottle neck in a drill to remove the thread with 80 grit paper.
After removing the sandpaper.

IMG_2388.jpg (1.58 MiB) Viewed 12 times

IMG_2386.jpg (2.01 MiB) Viewed 12 times

[anachronist]

I have to ask, what is the purpose in removing the threads? They don't contribute to drag because they're in a zone of turbulence anyway, and they add a negligible amount of weight. The threads are also useful; I designed and 3D printed a cowling with fins that screws onto the threads.

[Mike C]

Only reason is if you want to fit the top into a 22mm launch tube, you need to remove the thread.
I do like your idea of making use of the thread for securing additional fittings.