Drill bit sharpening

Lots of good advice here already so I won't add to technique--but I will say a few words about grinding the bit. Be careful not to overheat the bit, take your time, apply light pressure when grinding and have a can of water nearby to cool the bit in between tries. If you heat the cutting surface up too much, the temper of the drill bit will be changed and then it'll be either too brittle and crack easy or too soft and not cut. Last comment--maybe obvious to most folks, wear safety glasses and watch your fingers--they grind real easy too!!

For hand sharpening, here's a link. Scroll down a bit (no pun intended).

Link

- Mike

HTH

Jet

Get a new about 1/2" drill. Hold it to the belt sander (best) or grinder (works but not as easy) and study how to hold it togrind the angles.Do this with the belt sander off until you are ready to grind a dull drill. Hold it with the cutting edge you are sharpening up,shank of the drill to the left. The cutting edge should be horizontal. The shank lower than the point by a little. When you grind a slight upward motion of the point works for me. You need to grind each side (cutting edge) equally and to the same angle, holding the drill in the drill point gage tells you this. the leading edge,(cutting edge) needs to be "higher" than the trailing edge or it won't cut. To tell this hold the drill verticle infront of youwith the point up, slowly rotate it and see if thecutting edge is higher than the trailing edge. It is easier to learn on drills in the 5/16 go 1/2" range I think before going smaller or larger. After grinding hand stone the edges to a smooth surface, not changing the angles, to make the drill stay sharp longer. With a little practice you can save yourself the cost of a Drill Doctor, which works for a wile, but as the stone wears or the bushings wear, will not work as well. Some drills just don't seem to go well sometimes,but can usually be made to cut. If you get one of these, put it down and tr another one, come back to it later after you find it wasn't you, but the drill that was the problem.

The whole secret to that little task is to make sure you get the bit edge ground at the same exact angle as it was originally, but more importantly, you must make sure that you take just slightly more material off the heel than the face. And it doesn't take much; just a second or two against the wheel.

Takes a little practice, but in time you'll be able to just "feel" the angle of the grind.

Heck, I wouldn't buy a jig or a tool, just do it freehand using your shop grinding wheel.

Allan

With some practice on the motion it takes to duplicate the grind you will be a pro in short order.

For bits above 3/4 I still need to do by hand which I learned to do in High School. We made a guide first which helped a lot (wish I could find it).

For the machine shops I wouldn't touch the Drill Dr. To slow. There are quite a few companies that make industrial sharpeners including Darex (they make the Drill Dr) but those units start at about $600 and go up. Industrial units are available from machine shop suppliers like J&L, MSC, Enco and the like.

HTH

jt

If you have a bench or floor model belt sander (or its heavier-duty cousin, the belt grinder), try using it instead of a grinder when you tackle hand-sharpening a twist drill. The flat abrasive surface makes it MUCH easier to hand-grind a good drill tip.

Next tip: Written instructions for grinding drills by hand are not gospel, just a guide to help a person get started. Some folks find it much easier to achieve good results holding the shank of the drill in their left hand with their right hand holding near the tip, other folks have to interchange hand positions to get good results.

John

• hand sharpen

Another is using a shopmade jig. A 4 X 4" piece of plywood notched to fit up to the belt. Fasten a wooden strip (stop) at 59 deg to the belt then draw a few parallel lines 12 deg out from that stop, (59 and 12 deg) lines meeting at a point close to the belt. To use, place the bit against the stop with the cutting edge on the belt. Then rotate the bit clockwise as it is swung down parallel to those other lines you drew. About a 1/6 th total rotation is needed to sharpen each face.

When finished, place a washer with a hole slightly smaller than the bit on the cutting edge to check equal face lengths and if you actually cut enough relief for the bit to cut, by turning bit in washer. Start with a larger bit as it is much easier to see what is going on.

That shopmade jig is covered in "Woodshop Tool Maintenance" by Cunningham and Holtrop (1956) Pg 106 and those "Skill Books" SHARPENING put out by Pop. Science a few years back.