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.
(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
I drilled a hole in a piece of 1" plate last night started with a 3/8 inch center drill, then a 5/16 inch bit then a 5/8 then, finished it out so I could get a 3/4 inch boring in the hole with a 1" S&D Bit then bored it out to tap drill size for a 1.5 X 16TPI thread. Used a hand sharpened 3/8" HSS threading bit in a 1" boring bar for stiffness due to having to have the bit hanging out in the wind about 6 inches (had to keep carriage away for the one jaw that was sticking out of the chuck.
yep I know I probably did it wrong but I had the hunk of flat bar off center by about 2 inches.
Dallen,if it worked and there were no casualties then you didn't do it wrong.
So Dallen,
I thought it's only wrong if it doesn't work!
Jerry.
When working in a machine shop, all sins are easily forgiven, as long as the part turns out OK that is, but, even if you work to every best practice standard on earth if the part turns out wrong that's a whole other story, and no-one ever forgets about it either.
Rick
(09-19-2012, 10:55 AM)Rickabilly Wrote: [ -> ]and no-one ever forgets about it either.
Rick
ain't that for sure, specially my exwife
First project with lumber off the sawmill, actually poplar that blew down on the property. A drying shed for the hardwood we're producing.
NICE! That is simply awesome!!
Looking good Greg.
What type of mill are you using? Is it a commercial unit or one that you built?
Tom