Hi all
Got asked a question this weekend that calls for more accuracy than I have experience with, so I thought I'd ask for advice rather than guess.
Problem is a heated aluminum block to accurately and reproducibly align several components and heat cure the epoxy that holds the pieces together. Needs to be about 2" long, 1/8" in diameter and the diameter needs to be accurate to ~ .002" over the entire length to keep things concentric. Probably be done edge on into a 1/4" plate and there needs to be 20 - 30 of these holes per plate to keep production on track.
My gut was drill undersize and then ream to final diameter but I've only done that on relatively thin plate and have no idea how that would work over a 2" span on such a small diameter. I've also seen awfully good holes done with gun drills. But that was larger diameter and on a lathe, and this would have to be on done on a mill so you'd have to spin the gun drill, which sounds tricky to me (like how do you keep the air supply going through the drill to blow chips out?) and a 1/8" gun drill sounds pretty fragile. I expect there are exotic technologies out there that could do it, but staying within the usual machine shop, how would you approach this project?
Jim