Twist drill bits can dull with regular use and, without the proper tools, can be a bit tricky to sharpen. However, if you have a bench grinder with an adjustable tool rest, you can build a simple DIY sharpening jig that makes honing your twist drill bits easy. The jig is a piece of angle iron clamped to the tool rest that will hold the drill bit at the proper angle to ensure even sharpening on the tip of the twist bit.
Place the angle iron flat on the bench grinder's tool rest, with the end of the iron parallel to the face of the grinding wheel. The long edge of the angle iron should be aligned with the centre of the grinding wheel. Clamp the angle iron into place with a C-clamp.
Place a drill bit onto the tool rest, with one of the grinding edges (known as lands), and hold it against the base of the angle iron. The grinder should be turned off. Move the drill bit forward until the tip touches the grinding wheel. Adjust the angle of the tool rest until the bottom land of the drill bit is flat against the grinding wheel.
Back the bit away from the grinding wheel, and turn on the grinder. Ease the bit forward while holding it against the angle iron to grind the bottom land of the bit.
Remove the bit from the grinding wheel and flip the bit over. Repeat the steps, grinding the other land.
Inspect the tip of the drill bit. If one land appears to be longer than the other, grind the shorter land until the two are of the same length.
When grinding, hold the bit firmly against the angle iron and tool rest. There is no need to twist the bit while grinding.
When grinding with a bench grinder, wear safety glasses to protect your eyesight.