A friend of mine has a job to do... not due any time remotely soon, thank goodness. The piece is, if memory serves (I will correct later if need be), a large piece of 304 stainless. It needs to have a 1" square hole bored in it, 10" deep, not blind, parallel and true to +/- 0.0001". Yes, one ten-thousandth. Precision shaper is what I was thinking... or pre-drilling to 15/16" and pressing a multi-stage carbide broach through. I'm looking for out-of-the-box solutions to this, because frankly, I'm pretty well stumped. (For the curious, it's for some sort of laser interferometer.)
Things which I've thought of and discarded:
Cutting the part apart and machining the hole, then bolting it back together (Not allowed)
Waterjet (Inadequate precision, esp. at depth)
Laser (Inadequate depth)
Possible stuff:
Electron beam cutting??
Magic
Voodoo
Just something to strain y'all's brains over. :)