DIY Drill Sharpener

Turn off the bench grinder. Lift the protective plastic shield up and out of the way.

Place a 6-inch long piece of 1-inch-wide angle iron onto the tool rest. Position one side of the angle iron flat against the rest, with the other side protruding upward. The angle iron's long axis should be perpendicular to the face of the bench grinder's cutting wheel. The edge of the angle iron should be about 1/2 inch away from the cutting edge.

Clamp the angle iron into position with a C-clamp.

Place a twist drill bit into the V of the angle iron, with one cutting edge directly above the other. Slide the bit forward so its lower cutting edge is just touching the motionless grinding wheel. Loosen the tightening nut on the tool rest. Adjust the angle of the rest -- with the angle iron attached -- until the bottom cutting face of the drill bit is flat against the grinding wheel. Tighten the nut to lock the tool rest and jig into position.

Slide the bit away from the wheel, and turn on the grinder. Ease the bit forward until its bottom cutting edge touches the grinding wheel. Grind the bottom cutting edge of the bit for two to three seconds, then remove the bit to inspect the grinding. The cutting edge should be ground completely with no chips in the face. If it needs additional work, put it back in the jig and grind that face again.

Flip the bit over in the jig. Grind the opposite cutting edge in the same manner as you did the first edge.

Remove the bit from the jig and visually inspect the tip of the bit. Both grinding faces should be of the same width. If one is longer than the other, grind the shorter of the two faces until they are of equal length. Grinding the shorter of the two faces again until the two are equal will allow the bit to cut evenly.