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Fixing The Cutting Edge: Innovation Meets Table Saw

David Butler and one of his safer tools.
Chris Arnold
David Butler and one of his safer tools.

When you think of cutting-edge technology, power tools don't generally come to mind. Take the table saw: Many woodworkers are using 30-year-old saws in their wood shops and, among the major tool companies, there hasn't been much innovation since those decades-old tools came out.

But more and more inventors are trying to make these saws safer — and David Butler is one of them. At his home in Cape Cod, Mass., Butler flips on the fluorescent lights in his basement turned wood shop.

"I've been a lifelong woodworker," Butler says. And he has a dozen different power saws — table saws, band saws, scroll saws — to prove it, each of which is fitted with various prototypes of his invention.

Butler has spent most of his professional career as an electrical engineer — woodworking is more of a hobby. At 18, he was a Navy electronics technician working on the Navy's first fighter jet. In 1958, he started working for IBM. He says the company paid for him to go to school for eight months and then "turned me loose on the world's largest computer, the SAGE air defense system." From there, Butler went on to work for General Electric, Citibank and other major companies. And now, here in his basement workshop, Butler has come up with an impressive invention: a safety brake for table saws.

4,000 Amputations A Year And Counting

NPR has done a series of stories on another company, SawStop, that also produces a high-tech table saw safety brake. But despite the 4,000 grisly table saw amputation injuries that happen every year in the U.S., the broader industry has resisted adopting such brakes.

Now, Butler is the latest inventor to show that these saws could be a lot safer.

Butler calls his system the Whirlwind. It uses a blade guard cover and a vacuum that sucks away sawdust while you cut wood. If you touch the blade guard while the saw is running, it sets off a sensor that triggers the safety brake. The blade stops spinning in less than a second, keeping the user from accidentally running his hand into it.

Butler's system works using something called electronic braking. Power saw motors — like electric lights, appliances and basically everything we plug into the wall at home — run on AC power. It's the electrical power standard in the U.S. But, according to Butler, if you cut that power in exactly the right way, it's "like pulling the plug out of the wall." And if you then hit it with a jolt of DC current, that's like slamming on the brakes — within a second, Butler says, "you can stop the motor."

Whirlwind Vs. SawStop

Both Whirlwind and SawStop have their advantages and disadvantages. According to Butler's business partner, Robert Calhoun, one thing that's nice about Whirlwind is "you don't have to go out and buy a brand new table saw." Whirlwind is designed to be retrofitted onto any existing saw. Butler says even the 40-year-old table saw in your grandfather's basement could be made much safer by outfitting it with a Whirlwind safety brake. Whirlwind also doesn't destroy the saw blade when stopping it, so you can just reset the brake and keep working.

 David Butler designed his safety brakes so they could be easily installed on existing saws and machine tools. This prototype is installed on a Delta 15-inch scroll saw, a model that has been used for decades in schools.
Chris Arnold / NPR
David Butler designed his safety brakes so they could be easily installed on existing saws and machine tools. This prototype is installed on a Delta 15-inch scroll saw, a model that has been used for decades in schools.

But SawStop is faster — the brake kicks in within just a few one-thousandths of a second — and it also uses the saw blade itself as a sensor, so you don't need a guard covering the blade for the safety brake to work. Regulators and safety advocates say that's a distinct advantage because many woodworkers end up removing blade guards so they can work faster and more easily.

A Long Road To The Store Shelf

The biggest advantage, though, is that you can actually buy a SawStop saw. Whirlwind is still in the prototype stage and, unfortunately for woodworking enthusiasts, not being sold yet. That's because it's a long road from the drawing board to the store shelf, and so far the major power tool companies have resisted adopting this kind of advanced safety technology.

In fact, SawStop inventor Steve Gass had to start his own saw manufacturing company to bring his invention to market. But Butler says he isn't prepared to do that. He's looking to license his technology to another company to build and sell.

So far, none of the major power tool companies (including Delta, Ryobi, Black and Decker, Milwaukee and others) are even offering these types of advanced, so-called flesh-sensing safety brake systems on their saws. But that may change. The Consumer Product Safety Commission has begun drafting new table saw safety regulations — regulations that may very well require advanced systems like those invented by Whirlwind and SawStop.

Copyright 2020 NPR. To see more, visit https://www.npr.org.

NPR correspondent Chris Arnold is based in Boston. His reports are heard regularly on NPR's award-winning newsmagazines Morning Edition, All Things Considered, and Weekend Edition. He joined NPR in 1996 and was based in San Francisco before moving to Boston in 2001.
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