Steve Gass is out to change the tool world in a big way. The Portland, Ore., inventor is a woodworker and patent attorney who holds a Ph.D. in physics. His new safety device for table saws could mean the difference between a Band-Aid and an amputation. You've got to see Gass's SawStop in action to believe it. The electrically controlled super brake stops a full-speed table saw blade within 1/4 of a revolution when it comes in contact with a finger--even with a feed-rate as high as 60 feet per minute. Gass likens his invention to automotive airbags.
"This should be on every table saw sold," Gass says. And, if his early results are any indication of performance, eventually it could be. The SawStop sends a high-frequency charge to an electrically isolated blade and then monitors the blade's amplitude, looking for a rapid drop in the signals. Wood contacting the blade doesn't change the amplitude fast enough to trigger the brake. But a finger does. That's because the device detects the contact by sensing the finger's conductivity, which causes the blade's amplitude to plunge and triggers the brake.
Gass's brake jams a 1"x2"x6" piece of ABS plastic into the blade's teeth within 2 milliseconds of contact. It takes 2 to 3 milliseconds to go from contact to a dead stop--quick enough to leave the finger with only a 1/16-inch-deep cut. Without this device, Gass estimates even the quickest woodworker's reactions would result in a 3 1/2-inch-deep cut or losing a number of fingers. The safety-stop trashes the brake cartridge. But the cartridge slides off the saw easily, ready for a $20-to-$30 replacement.
You're probably asking yourself, "Who the heck tested this to see if it works?" Fair question. Most of the testing has been done with stand-ins that have the same conductivity as human fingers--a team of specially trained hotdogs. But Gass, the consummate inventor, couldn't ask an actual human to use his SawStop if he hadn't backed it up with his own blood, sweat, and tears. Actually, he'd hoped to limit it to just the sweat and tears. "Forcing my finger into that blade was the hardest thing I've ever done," says Gass. "Every instinct was fighting what I had to do." His invention worked though, and Gass avoided becoming one of the estimated 3,000 people who lose fingers on table saws each year.
Don't look for the SawStop on the shelf anywhere--or on tools anytime soon. The brake will most likely end up installed as original equipment by tool manufacturers. And while Gass has begun discussions with a number of companies, the reception has been mixed. After all, industry-wide efforts to re-design and re-tool existing product lines to incorporate these devices would take a lot of time and would have a massive impact on manufacturing. On the other hand, who could ignore its existence?
Gass has only conducted his own tests and demonstrations, so the SawStop hasn't gone through UL testing or any other organization's ratings. That, he says, will be up to tool manufacturers who adopt the technology. So far he's only tried it out on table saws, but he is sure the device has applications for all types of saws, and maybe even jointers. Gass estimates a SawStop brake would add $50 to $100 to the cost of a table saw. Check out the company's Web site at www.sawstop.com.