Does there seem to be a standard Nozzle thread? I’d like to attempt a hot-end with the nozzle from my dead extruder and figured I’d ask while away from my man cave.
Most I’ve come across are m6 threads.
Yep, M6 threads are the most common. Pretty sure the J-head is not M6 however. The J-heads are documented though, and if you can’t find it; email the guy who makes them at http://hotends.com, he’ll tell you.
Yup, the Jhead uses one of those great imperial threads, something like 4/31-17-42u-6s0. More details and actual dimensions on the reprap wiki: http://reprap.org/wiki/J_Head_Nozzle#Version_6
All-metal hotends and modern mostly-metal hotends seem to all use M6, but often in an incompatible way where, for example on the nozzle, some use an external thread and others an internal one.
I looked it up 5/16’s isn’t THAT bad…a bottoming 5/16’ths tap for the Cold end is a little cruel and unusual, though.