Burning. Burned edges (left) mean the blade is too fine for the material. A coarser blade clears sawdust better, reducing friction and burning (right).
Tearout or splintering. Torn fibers on the bottom surface of your work (left) can usually be avoided (right) by using a reverse-tooth blade.
Meltdown. Standard blades and fine-tooth blades tend to melt acrylic (bottom), but coarser "crown-tooth" blades produce a smooth edge (top).
PGT blades arc reverse-tooth blades whose teeth are precision-ground rather than milled, so they produce straightcr, smoother cuts than standard blades in many materials.
Spiral-tooth blades cut in every direction, but they leave a ragged edge. They're best for work that is too long to swing through the throat of your saw.
Blades come in numerical sixes ranging from #2/0 to #12 and coarser. Lower-numbered blades are thinner and narrow er and have more teeth per inch (tpi).
The most important factor influencing your choice of blade size is the hardness, or density, of die material you're cutting. Hardwoods and other dense materials generally cut better with coarser blades. Very thin materials such as veneers and thin plywood require fine-tooth blades.
The chart below shows the blades that I've found work best for many common materials. If you don't get the results you want, a few rules of thumb will help you select a better blade for the job. (See "Troubleshooting Guide,'' above.)
Many woodworkers just starting out on the scrollsaw don't tension their blades enough. Insufficient tension will make the blade tend to drift when sawing and will cause premature blade breakage, usually near the center of the blade. Breakage at the ends of the blade usually means your blade holders arc not pivoting freely, causing metal fatigue near the holders.
I've heard of people gauging blade tension by the pitch of the blade when it's plucked, but 1 prefer to use the u,/g-in. rule"—the blade shouldn't deflect more than !/g in. when you press your work against it. Blades stretch slightly in use, so it helps to periodically re-tension your blade as you work. A
MARC BERNER is a woodworker and scrollsaw expert based in northern California.
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