Bry,
It just so happens, I did build the hand built R-R's in times gone past. The factory where it used to happen is only about 1.5 miles from where I live.
My machine shop was built to provide affordable high precision small order contracts. Unfortunately that was kicked in the head due to personal reasons.
But now I am on a slightly different slant, something I can easily cope with, designing and/or making one off's for people who don't have machining facilities, and aren't too worried over time scales and how much it will cost. Outlays for tooling are very quickly recouped, and I am not worried if nothing goes into my pocket. Doing it that way, my shop costs me nothing other than a bit of my time and effort.
When you do work for other people, you can only give them the best, and so the tooling for that sort of work is where the most money is spent. Rough a**ed work for myself and other people, plus if people want to borrow my tools, then the old sets of taps and dies get used.
I have found that the T&D company supply cutting tools in HQS. I don't know what that means, but once you use them to cut stainless, you don't worry about what they are made of, they just do the job with no problems at all, like a hot knife thru butter, unlike the HSS ones I used to use for such jobs, which really struggled at times. For 3mm and above, all thread cutting in my shop is done mainly by machine or power tools.
Like below, power tap the brass fingers with a 5mm LH coarse tap on the lathe, then single point the same thread onto the SS rods for a perfectly straight and perfect matching thread.
Don't ask what it is for.
Bogs