Sharpen Drill Bit

[handyandy]

I have a very dull bit, but it is long and expensive, what is the best way to sharpen it? I saw the Drill Doctor, is it worth it? Or should I just try to file it?

[HayZee518]

what's the drill made of? just regular metal or carbide tipped?

[handyandy]

just a regular drill bit. There are several actually. Thanks for the reply, I love this place!

[HayZee518]

Most drill bits can be sharpened manually with a fine grit wheel. The web, the midpoint between the two flutes should be maintained at a 60 degree angle, 1) to make it drill accurately and 2) to give a sharp cutting angle. The back side of a cutting edge is called the "rake angle."

[highsider]

I have one of the drill doctors and am happy with it. I'm a retired machinist however and do a lot of drilling in metals. The thing I like about them is the split point feature. This grinds the web of the drillbit, to extend the cutting edge of the flute right into the center of the bit. This makes for easier and more accurate drilling in harder metal.
Last I saw, the price on these was aprox. $150. If you have manual dexterity they can be sharpened on a bench grinder. Start with a freshly dressed grinding wheel and the tool rest adjusted to within 1/16" from the wheel (safety item). If you must wear gloves use leather. Any kind of fabric is a no no. (safety again)
Position the bit with your R hand holding it near the cutting end and your L on the end without flutes. Without touching the wheel yet, lay the cutting end of the bit on the tool rest with the rear of the bit about 30 degrees to the left. Now rotate the bit till one of the cutting edges is horizontal. Lower the end in your left hand just a few degrees and gently bring the cutting edge in contact with the wheel, at the same time rolling the bit down with your left hand. Try to grind a little more (deeper) as you roll it down. This will produce enough clearance at the "heel" of the bit to let it drill instead of rub. After a couple of strokes, roll the bit in your fingers to bring the other cutting edge to the same position and do the same there. Try not to overheat the bit and have some cooling water to dunk it in as needed. When your finished, if you hold the bit verticlely and look at the side of each flute where you've ground, the toe (cutting edge) should be noticably higher than the heel. Then if you look straight on at the two cutting edges,(like you were going to drill your eye) they should meet fairly centered across the web and the cutting edges should be the same length and angle.
This sounds complicated, but isnt. With very little practice your hands will pick up the feel of it, and within a short time you'll be able to sharpen a bit and never forget how.
You won't be able to sharpen a drill bit with a file, they're to hard.
Good luck

[driz]

One of my buddies father is a retired mill wright and he said you can use a large nut as a guide to keep you at the right angle, TRUE OR POO???? It seems too convenient but if I drop one off he gives it back pretty sharp.

[HayZee518]

360 degrees divided by 6 equals 60 degrees. the web angle of a drill is 30 degrees so the nut thingie won't work

[driz]

No wonder I couldn't get it to work. I will have to go cut a piece of half inch plate to 30 on my chop saw and weld a small stand on it and try that. I have a HF rig with some sort of tray and screw arragnement but never could manage to make the thing work

[HayZee518]

Machines have been made to sharpen drill bits. In most cases they work, but for the weekender DIY, knowing how to hone up a bit so it cuts doesn't take a rocket scientist to figure out. A drill bit can have two flutes or four flutes or any in between. Four flutes usually is referred to as a core drill with a hollow center.
Look at a drill tip. You'll see a flat area, this is called the web. One of two edges is the leading or cutting edge. The flute that follows is the rake. This rake is tapered at an angle to the cutting edge to provide a path for the cut metal to follow out of the work. Feed pressure should be constant to keep intimate contact with the work to remove metal and keep the edge cutting.