How to Grind a Dubbed Twist Drill

Dubbed twist drill bits come in handy for drilling precise holes through various metals, such as steel, aluminum, copper, brass and other alloys. Drill bits, especially carbon-tipped bits, have special hardened cutting features that allow them to pierce through softer metals without losing much of their cutting sharpness. However, after wear and repeated use, drill bits become dulled and deformed by heat and pressure. An ordinary repair person can sharpen their own drill bits with a grinding stone and a little skill.

Instructions

1

Take your drill bits to a workbench, equipped with a grinder that has a flat, circular cutting stone. Equip the grinder with a diamond cutting stone, if possible, for a cleaner and more accurate cut that requires less pressure. Lay out your worn drill bits in the order you wish to sharpen them.

2

Don a pair of safety goggles and gloves. Without turning on the grinding machine, lay your bit up against the cutting stone, with the bit tip angle perpendicular to the grinding stone face. This angle is about 59 degrees, for a worn bit head.

3

Hold the shank of the bit in the forefingers of one hand, and use the other hand to support the gripping hand. Use the fingers of the supporting hand to grip the end of the bit shank. The holding hand will rotate the bit shank, while the gripping fingers hold the bit against the grinding wheel.

4

Practice making the three moves required to sharpen the drill bit properly. Do not start the grinder yet. Move the bit shank left and slightly downward, while at the same time rotating the bit left (counterclockwise). Pull the bit away after several rotations. Perform the motion several times, until you are proficient with the move. Turn on the machine.

5

Ease the drill bit up against the grinding wheel lightly until you make contact. Apply a small amount of pressure as you twist the drill bit shank to the left. Rotate the drill counterclockwise with your supporting hand, while pulling down simultaneously. Make several complete rotations then turn off the grinder.

6

Hold the drill bit up to the light and see if the angled edges look equal and uniform. The tip should have a sharp point. If not, turn the grinder on and repeat the process, but with a little more pressure. Sharpen all of your drill bits in this fashion.