The Best Grinder Speed for Sharpening Drill Bits

Temper

• Drill bits must be sharpened with a grinder set at low or medium-low speed. The bits, along with almost all other steel tools, are tempered -- or hardened along the edges -- with a heat treatment. If the sharpening process raises the temperature of the edge beyond the tempering point, the edge will lose its ability to stay sharp. The friction from a high-speed grinder easily causes metal to heat up.

Edges

• Straight-edged blades such as knifes, machetes, axes and lawnmower blades are quickly sharpened with a few swipes of a stone along the edge. It takes some time and experience to learn the proper angles and techniques, but the practice is relatively simple. However, drill bits have complex edges and geometry that make them much harder to sharpen. Many types of sharpeners claim they will provide the best sharpening for a drill bit.

Dedicated Units

• Dedicated drill sharpeners provide an all-in-one tool for the bits. The largest models even sharpen what are referred to as spade bits, or ones that have flared wings projecting out of the shank on two sides for larger holes. Because the unit does all the work of properly holding the bit, it is easier to learn and use. If you use your bits under heavy-duty conditions, a grinder such as this quickly returns its investment.

Jigs

• Sharpening jigs are special holders that allow you to sharpen the bits using a regular bench grinder capable of slower speeds. The jigs range from simple to complex, with the more complex capable of giving multiple angles for different types of drilling. Even at low speeds, it only takes a few passes to sharpen a bit. An easy mistake for beginners is to grind the bit far too much, which removes more metal than is needed and shortens the life of the bit considerably.