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Angle on bottom of special drill bit

Guys, I am making a drill bit that is 1 1/4" in diameter. This bit is for drilling end grain wood on a wood lathe. That is, the drill bit will not turn, but the wood does. Essentially the cutter is a piece of 5/8" wide planer blade that is brazed to the end of a 1 1/4" tube. The trailing side of the planer blade is ground away so the leading edge is in contact with the wood. I want the drill bit to advance 1/8" per revolution. What is the clearance angle I need too achieve this. That is, what angle should the bottom of the cutter make with the axis of the bit? Incidentally, an air tube ending just above the cutter takes the shaving out the top of the bit, very similar to a rifle drill.

Gotta be someone on this group who can tell me the answer.

TIA, James Johnson

Reply to
JRJohnson
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"JRJohnson" wrote in news:Vsi7e.9$ snipped-for-privacy@tornado.texas.rr.com:

If the cutting face is perpendicular to the work (no rake), 8-12° should work fine.

Reply to
Anthony

What you've made is basically a spade bit. If you advance 1/8"/ rev. it is going to make a very rough hole and possibly jam or split the wood. Ideally the bit will take about .003" to .005 per rev. and make a nice clean hole zero to three degrees of relief should work. Bugs

Reply to
Bugs

Actually, Bugs, the one I made which drills 1/9"/rev actually makes a very clean hole. Plus, the hole is only so the woodturner doesn't have to turn out the center of the piece, which is not moving very much in relation to most of the piece. I can measure the clearance angle of the one I made and guestimate, but thought I would give the group something to think about.

Also, after the hole is drilled, the inside of the piece is immediately turned away, so the actual smoothness of the hole is of no consequence.

Regards, James Johnson

Reply to
JRJohnson

How about using a Forstner bit?

Mark Rand RTFM

Reply to
Mark Rand

Yea. Can you imagine 1/8 in feed per rev. ???? :-) I wonder how many horse power that drill press has? and what sort of down feed gearing?? Sorry. I was going to ignore this but I see there is a at least one response. :-) ...lew...

Reply to
Lew Hartswick

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