Detecting metal in lumber before you cut it is one way to save sharp tool edges. Here are several more.

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Few things satisfy a woodworker's soul like the sensation of a well-honed tool effortlessly slicing through lumber. Getting your tools that sharp takes a lot of effort, so you want to enjoy it for as long as possible. Not only does this experience heighten your satisfaction, but sharp cutters also reduce splintering, tear-out, and burning with less strain on your arms and your machines' motors.

Give stock the ol' brush-off
Before you make a cut, inspect the lumber for foreign material that will nick or dull your tools. Be especially attentive to reclaimed stock, such as that shown above, which might contain debris on and under the surface.

Start by cleaning

Remove any visible dirt or grit with a wire brush or belt sander. Your wood could be embedded with nails, tacks, or staples, so pull or cut away any that you find, as shown below. To be sure you get them all, run a handheld metal detector along the board's surfaces, as shown second below. Cut off a board's ends, as shown third below, before measuring and marking any project parts—these ends collect grit, especially if stored vertically.

Needle nose pulling out staple
Home-center lumber often containseasy-to-overlook staples. Usepliers or a screwdriver to pull thesebefore machining.
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Green miter saw

Help cutters keep cool

Pitch and residue buildup on saw blades, router bits, and planer and jointer knives generates heat while you're cutting wood, and that accelerates dulling. Use a commercial cleaner, such as Empire BladeSaver (16 oz, woodcraft.com or 800-225-1153) and a stiff-bristle brush to soften and remove the grime, as shown below. Do this anytime you see buildup on or around the cutting edges.

White brush on sawbalde
With a protective paper or towel belowthe blade, spray cleaner onto the teethand let it soak 5-10 minutes before scrubbing.

Spread the work around
To prevent your planer knives from dulling unevenly, alternately feed boards against the left and right sides of the table. The middle of the knives will inevitably dull quicker than the ends, but you'll minimize the effect.

Likewise, with your jointer, move the fence forward and back to evenly distribute the wear on your knives as you joint board edges.

Save knives from plywood

Although you might be tempted, never use your planer or jointer to machine manmade materials, such as plywood, particleboard, tempered hardboard, or medium-density fiberboard (MDF). The glues in these materials quickly dull steel knives, as shown below on the plywood above right after we rubbed blue chalk on it to highlight the uneven cut. However, you can machine these products—sparingly—on jointers and planers equipped with carbide knives, which hold their sharp edges longer than steel knives.

Streaks on blue cover board
After just a few passes edge-jointingthis plywood, the knives wore enough at the glue bonds to make ridges ona face-jointed board.