Make cleaner jigsaw cuts
The road from Splinterville starts at the blade
Choose the right tooth count for the cuts you make. Blades with aggressive 6-tooth-per-inch (tpi) designs work great for sawing construction lumber, but cut too coarsely for woodworking project parts. Instead, select a 10- to 12-tpi blade for larger, gradual curves, or a 20-tpi blade for tight curves (1" radius or less) in solid wood and all cuts in plywood or melamine-coated particleboard.
Beyond tooth count, also consider the blade design. For decades, jigsaw-blade teeth were "set," alternately leaning left and right, as shown in chart. This makes them cut coolly and quickly, but at the expense of cut quality.
To remedy this, several manufacturers now make blades with ground, inline teeth, as shown chart, that slice the wood like a surgical scalpel rather than bluntly tear at it. This produces much cleaner cuts. For this reason, in the WOOD® magazine shop we use Bosch Clean-For-Wood and Bosch Xtra-Clean-For-Wood blades. Just be aware that these blades can burn your wood if you set the jigsaw's speed too fast or feed the saw through the wood too slowly. Our best advice: Practice on scrap of the same species to find the best combination of speed and feed rate.
Finally, remember that jigsaw blades cost a fraction of the material you're cutting. So know when to call it quits on a blade. If a blade begins to burn the wood or tear out surface fibers where it didn't used to, or if it requires greater effort to push through a cut, chuck it and get a new one.
U-shank blades tend to wobble, flex more, and produce more tear-out than T-shank blades. If you own a jigsaw that uses these blades, unfortunately, you have fewer options in blade choices. Opt for higher tooth counts as much as possible to reduce tear-out.
Progressive-tooth blades have a greater hook angle near the tip, putting those aggressive teeth where they're needed for fast cutting in materials thicker than 1". Less-aggressive teeth close to the shank end help the blade cleanly exit the top surface of the workpiece.
Standard 6-tpi blades
Standard 6-tpi blades use steep hook angles on the teeth and large gullets between them for quick waste removal. These blades work best when speed is more important than cut quality, such as working with construction lumber.
Reverse-tooth blades cut on the downstroke, minimizing chip-out on the face side of a workpiece when you must put the best face up during cuts. Making a sink cutout in a countertop calls for one of these blades.
Now set up the jigsaw
For softwoods, softer hardwoods (poplar, mahogany, alder, etc.), and sheet goods, run your jigsaw at its highest speed for most cuts. If you encounter resistance, back off the speed slightly. Dense hardwoods, such as cherry, maple, oak, and walnut, call for a slower blade speed to avoid burning. Use the slowest speed setting for cutting plastics and metals.
If your jigsaw has an orbital setting—an internal action that rocks the blade in a pendulum-like motion while simultaneously stroking up and down—set it to the greatest orbit for fast, but rough, cutting. Turn off the orbital action for cutting curves with less than a 3" radius. But if you're cutting large, sweeping curves, a little orbital action helps.
You also can reduce top-face workpiece tear-out by adding a zero-clearance shoe, such as the one shown at right, to your jigsaw. Make it from 1⁄4 " hardboard and secure it to the saw's foot with machine screws or double-faced tape. Ease the corners and edges with sandpaper to prevent making any scratches on your workpieces.