My dad sharpened drill bits on a piece of sandpaper for years, and I thought he was just being cheap. Then I tried it myself and realized he was being smart. The trick is so simple it feels like cheating.

Dull drill bits burn wood and take forever. A sharp bit cuts clean, and you can bring one back with sandpaper in about a minute.

The trick: drill into the sandpaper

Lay a sheet of medium grit sandpaper flat on your workbench. Put the dull bit in your drill, and run the drill against the sandpaper at the same angle it cuts. Ten seconds of gentle pressure on each side of the cutting edge, and the bit is sharper.

Why it works

The sandpaper grinds a fresh edge onto the bit. You are not reshaping it, just refreshing the cutting surface. For bits that are dull but not damaged, this brings them back to near new.

Use the right grit

Start with 120 grit for a dull bit, and finish with 220 grit for a smooth edge. If the bit is very dull, start coarser with 80 grit. Keep the sandpaper flat so you do not round off the tip.

Match the angle

The bit cuts at roughly a 60 degree angle at the tip. Hold the drill at that same angle against the paper. You can see the cutting edge as it passes, and you want it flat against the sandpaper, not rocking.

Do it before you need it

The best time to sharpen is before a project, not mid-project. Check your bits before you start, and spend one minute on each dull one. It saves the frustration of a bit that skates across the surface.

When to replace instead

If the tip is chipped, bent, or the bit is snapped, sandpaper will not save it. Worn out is worn out. But for normal dullness, sharpening beats buying every time.

I called my dad to tell him the sandpaper trick works, and he just laughed. A thirty cent sheet of sandpaper has replaced a box of new bits in my toolbox.