09-19-2012, 05:52 AM
(09-18-2012, 07:16 PM)f350ca Wrote: I'd do it in 3 steps Ed. A pilot hole first then 1/32 under the size you want followed by your final bit. If the cutting edges on your drill aren't equal length, (mine never are exact from sharpening) it will drill oversized till its just about to break through, then you'll see the tell tale smaller diameter at the bottom of the hole. If the flanks of the drill are different length or the bit isn't chucked perfectly straight it will still drill oversized till the point is buried in the previous bore.
Greg,
That sounds like a reasonable method. I was thinking about how I did it and I did not go up in 1/32" steps as I previously stated. I went up in 1/8" steps until I got close to 1/2" and then used a 7/16" followed by the 1/2". Last evening I finished drilling the hole and used 5/8, 11/16 and then the 3/4" bits. The hole is 3 1/2" deep and the large bits must have flute lengths of about 4" because there wasn't much of the flutes showing when I broke through. Those big bits are scary.
Ed