January 5, 2008

I need to get this bushing hole right before I do anything else. Today was dedicated to that. I went out and got a unibit tapered drill bit for the job and tried that out. I got to the 7/16 size and checked the hole size with calipers. Too big by .02-.03"! It doesn't look like the bit is wobbling in the chuck but it must be ever so slightly, or else the unibit is oversize. I'm guessing it's my press or vibration because the 7/16 reamer also makes the hole too big. One good thing about the unibit is that since it steps up to the size hole that I need, it's really easy to drill that big hole cleanly. So next, I tried using the unibit to the step before 7/16, which was 1/32 smaller. Then I used a regular twist drill bit 1/64 bigger than that hole (27/64). Then finally a twist bit another 1/64 bigger for the final 7/16 hole size. I let those twist drill bits sort of self center on their own. It worked! My practice hole sizes were anywhere from .365 to .385 and the bushings are around .400, so the press fit should be good. I also read something in a Tony Bingelis article about using Loctite when you press in the bushing as well. Sounds like a good idea.

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