Q:

I bought a set of double-flute auger bits that I’d like to put to use, but they’re all kind of dull. How do I sharpen them?

Jimmy Clement, Jamestown, NY

A:

When sharp, auger bits slice cleanly and quickly through wood with minimal effort. There are three things to check before you can use the bits. The lead screw, which pulls the bit into the wood, must be straight and have clean threads. The cutting spurs, which cut the outside of the hole, must be sharp and the same height as one another. Finally, the ramps, which clean out the interior of the hole, should be sharp.

If the lead screw is bent, straighten it with a pair of needlenose pliers. Clean up the threads and correct minor damage to them with a feather file.

Next, sharpen the two cutting spurs with a small triangular file, taking care not to cut into the ramps. Work only on the inside face of the cutters. If you file the outside face, you’ll change the bit’s diameter. And be careful to keep the spurs the same length (the bit won’t cut straight and clean if they are different lengths).

Finally, sharpen the ramps. These ramps function like plane blades, except that they turn around an axis. Sharpen them by moving the triangular file in an upward motion along the ramp and toward the flute. Take care to maintain the ramps’ angle and to remove the same amount of material from each one.

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