Advice Needed, Drilling A Hole On The Edge Of A Piece.

T Bredehoft said:
A fixture utilizing the center boss, (.125) with the .038 hole .100 from the center would leave .020 between the guide hole in the center and the pilot hole for the .038 drill. Good Idea, but just too small.
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Spot both holes first (then you can verify the spacing). Then drill the .038 hole. Then drill the center hole. Use stub drills, preferably carbide. Use steel (or maybe durabar) for the material.
 
It all sounds good. It's gotta be aluminum, weight is the enemy. Its a hobby factory for hobby people, can't afford carbide drills. The clutches sell for $4.00 ea. I'll manage, the new drills gotta be better than what I have.
 
118º Works on my Dell laptop (alt 0186) Old dog learned something... wondering how to do this without doing it in MS word)

I'm dangerous now, lookout!
 
T Bredehoft said:
It's gotta be aluminum, weight is the enemy.
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I meant use steel for the drill guide, not for the part. I was suggesting a way to make the guide despite the holes being close.

You might want to make the guide to fit over two or three of the posts so that it is fixed against rotation. You could also drill a guide hole in it for your other hole.
 
T Bredehoft said:
It all sounds good. It's gotta be aluminum, weight is the enemy. Its a hobby factory for hobby people, can't afford carbide drills. The clutches sell for $4.00 ea. I'll manage, the new drills gotta be better than what I have.
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Tom, I buy a lot of my carbide PCB drills at hamfests. I have bought them for as little as $5.00 for a box of fifty. They are available on e-Bay for around $20 -25 for a box of fifty and around a buck apiece for lots of five. Here are a couple of links.
http://www.ebay.com/itm/Lot-of-50-R...121570?hash=item25a27142a2:g:VPgAAOSwNSxVBlZ3
http://www.ebay.com/itm/038-62-1-8-...458595?hash=item259c8fc863:g:SbcAAOSw7ThUogQr
 
RJ, son of a gun, I'd never have guessed. I'll get 5 of them, they ought to last a while. My max speed is near 2500, is that fast enough for them?
 
T Bredehoft said:
RJ, son of a gun, I'd never have guessed. I'll get 5 of them, they ought to last a while. My max speed is near 2500, is that fast enough for them?
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2500 is slow for a drill that size but if you go slowly it will work. I have drilled thousands of #72 holes with a 1750 rpm drill. Use a lubricant and fairly light pressure. The carbide bits are good at feeding themselves. If you use a drill guide, be sure to blow any chips out between holes as aluminum chips like to clog up the flutes and can bind which will break the bit.

Good luck with them and let us know how it works out.
 
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