Quote:
Originally Posted by JesseK
Side topic -- somewhat related I suppose --
For a 1-1/8" (or 1-1/16") Silver & Demming bit that would cut into 1/4" Polycarb and/or 1/4" Aluminum ...
... would we want to get a carbide-tipped bit or would a HSS bit suffice? This assumes that S&D bits can do the 1-1/8" hole without too much slop, which also assumes we would do starter holes with a smaller drill bit first. It would also be done on a mill we've been able to get within 1/64" after nominal practice.
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HSS would definitely suffice, though I prefer to get coated and/or carbide tooling because it is so much more durable. To quote the machinist I worked with at my college: "it costs twice as much, but lasts five times longer."
My opinion is that for 1/4" and thinner you'd be better off with a good quality step drill, hole cutter, and/or reamer, depending on what sort of fit you wanted. I don't like how big drill bits like that are not very forgiving. They can make 'triangle holes' and catch big burrs and spin parts when they're used in thin material.