Threads on both ends of the body, and top end of the cap are 20 tpi. The cap to body connection is kind of a combo. I didn't want to mess with 2 or 3 start threads, but didn't want a bunch of turns either, so I tried to making a shallow 10 pitch thread. The female used a regular V thread. The male thread is a modified V. There is an oilfield thread called an MT, it is 60* with a .055 flat instead of full V profile. It is also a 6 pitch thread. So I played in AutoCad and came up with what it would look like run as a 10 pitch. Still deeper than I would like, but I had plenty of material
. Also the advantage of the full size machines at the shop. I intend to give double or triple start threading a go on one in the future, and will come up with a size that fits what I am doing. At least that's the plan!