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Re: How to Make a Clean Hole with 1 1/8" Dill Bit?
for drilling any holes start with a center drill to make a pocket for the drill point to follow. After that for anything large you need to incrementally increase or "step up" your drill sixes. Make a through hold with a 1/4 and go from there. For Al i would say you are safe increasing by 1/4 for each step. (So 1/4 to 1/2 to 3/4... ) to your end size. If it is something harder like steel then increase from 1/4 in 1/8 steps. If the hole needs to hold a tighter tolerance it may be worth your money to undersize the hole and purchase a reamer of the proper size, ream it to an interference fit, and then press the bearings into place. All of this can be done in the cheapest of drill presses as long as you're careful. Make sure your cutting speeds match that of your material, use good HSS bits, and use lube. For lube, i prefer either safetap or mobil thread cutting oil for general purpose use. Although for a tight tolerance and very good finish machining Al i personally use JP 54 jet fuel. Disel will also work in a pinch but it will leave a bit of a residue that will need scrubbed off with either alcohol or acetone. Do not use fuel oils on steel though, if you get overzealous and spark off the drill you will have a very very bad day. Hope this helps!
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