Play it Safe with Add-ons
Joplin, Missouri, reader Thomas DeSanto wrote to express his thoughts on safety. Here's just one: "Some people might say safety is too expensive and too much trouble; but it isn't as bad as having a glass eye fitted, or getting a hearing aid, or trying to do without a few fingers." I like his line of thinking, although I try to be more positive.
I've also read the safety related concerns generated in the WOOD Online discussion group at WOOD magazine's Web site (http://www.woodmagazine.com). Several cyber-readers wanted safety opinions on using the tablesaw fence as a length gauge for repetitive crosscutting. So, for everyone's benefit, here are my thoughts on the subject.
You've seen it done: Someone clamps a stopblock of scrapwood to the tablesaw fence. Then he adjusts the fence to act as a cutoff gauge for repetitive crosscuts.
Above, in illustrated form, are two examples of what can go wrong with that setup. In the first example, drawing 1, with the blade guard in place (and no matter what you say, it should always be), the cutoff rotates between the blade and the fence, wedges, then kicks back toward you. In the second example, drawing 2, without the guard, the cutoff rotates, contacts the back of the blade, then kicks back. In both cases, it's the fence that's the culprit because it doesn't allow the cutoff to escape.
Drawing 3 shows you the safest way to do it. Remove the tablesaw fence from the table, and clamp a stopblock to the table in its place. Be sure the stopblock is parallel with the blade and yet doesn't intrude on the blade's cutting path. Also be sure that it's securely clamped to the table.
Feather boards—those fingered devices you clamp on to hold the workpiece in place as you rip—are meant to prevent kickback. But that's only if you install them properly. Like any other tool or accessory, there's a right and a wrong way to use them.
On a tablesaw (or radial-arm saw), a correctly positioned feather board holds the workpiece against the fence, as shown in drawing 4, below. This keeps its alignment true to the blade, assuring a straight, clean cut. Should the saw blade try to kick the wood back, the fingers of the feather board quickly help stop the board's reverse motion.
But, if you clamp the feather board in position so that it pushes against the side of the blade, as shown in drawing 5, it will actually cause kickback. That's because as the blade cuts the workpiece, the feather board pushes against the offal piece to pinch the blade,
Mike Gililland is a lifelong woodworker and an engineer with 25 year's experience designing and working with woodworking power tools to make them safer. A resident of Missouri, he owns and runs a safety consulting firm.
Illustrations: Kim Downing; Lorna Johnson