Vindication arrived for Stephen Gass on the afternoon of June 28, 2006, when someone finally agreed with him. It had been nearly seven years since Gass invented his skin-sensing table saw, and in that time he’d begun to wonder if anyone would truly see the wisdom behind his device. Over the years, the responses he received from the power tool industry graduated from indifference to hostility. He’d gone from being a rejected outsider to a festering industry sore. And by 2006, Gass himself had considered quitting many times.
But on that June day, everything changed. Someone understood. Acting on a petition from Gass, engineers at the U.S. Consumer Product Safety Commission recommended that the government begin a “rulemaking process” that could result in mandatory safety standards for table saws. Days later, the agency’s commissioners shocked the power tool industry by concurring with the recommendation. They saw the wisdom in his petition. Suddenly, the ultimate outsider joined the game, and now he was holding a strong hand.
“Here we had an unbiased government agency saying these saws are unreasonably dangerous,” Gass says now. “So, yes, I did feel somewhat vindicated.”
To be sure, the decision could mean little for Gass’s tiny, barn-based business, known as SawStop LLC. Power tool makers undoubtedly will search for other ways to satisfy the Consumer Product Safety Commission, without using SawStop technology. But for Gass, it’s the biggest victory yet in what has been an uncertain, uphill battle. In many respects, his public clash has made Gass a poster child for all inventors who deal with the so-called “not invented here syndrome.” Moreover, Gass’s story adds another human dimension to such dramas, seeing as how it also deals with the very commonplace — and tragic — loss of human fingers. By sitting down in his barn one afternoon in 1999 and finding an innovative way to reduce the sudden amputation of fingers, Gass raised the level of discussion — as well as the level of emotion — in an industry that had long accepted a certain, brutal, status quo. That’s why he sees the Consumer Product Safety Commission’s decision as a form of recognition. “I suspect that some of the executives at the major tool companies are going to be pretty unhappy about it,” he says.
Meager Beginnings When Gass first dreamed up the concept for SawStop, he never imagined his relationship with the power tool industry would ultimately be an adversarial one. Gass, now 42, was puttering in his barn-based woodwork shop in 1999 when his “Eureka!” moment struck. A patent attorney with a lifelong passion for woodworking, he wondered if it would be possible to stop a spinning, 4,000-rpm saw blade fast enough to prevent serious injury after an inadvertent touch. Gass, who, in addition to being an attorney also holds a Ph.D. in physics from the University of California at San Diego, began to tick through possible sensing methods for such a project. Proximity sensors? Optical sensors to look for blood? Ultrasonic sensors to check for saw vibrations? After considering those possibilities and more for about 30 minutes, his mind began to settle on another method: electrical capacitance.
“Ultimately, it seemed like the most reliable technique would have to involve contact detection,” Gass recalls. “And because your body has an electrical capacitance, it offers the potential for that. I figured that if you put a voltage into the saw blade, your body could absorb some of that signal. Then the voltage in the saw blade would drop.”
Within a week, Gass formulated most of the idea’s details in his mind. Thirty days later, he completed his first working prototype. Initially, he tested the prototype by touching the side of the saw blade with a finger. And while that proved the saw could stop in a fraction of a second, he still didn’t know if it was quick enough to prevent serious injury. Gass wondered how deep a 4,000-rpm saw blade would cut into human flesh during the microseconds that it took to stop the blade. To answer that, he needed to touch the blade teeth.
“I came up with the idea of using hot dogs, and it worked pretty well,” Gass says. “It’s cheap, readily available, and you don’t get any protesters coming to your door.”
While doing the development work, Gass was still employed as a patent attorney. At the time, he planned to remain in his job, refining and patenting his new technology at night, ultimately licensing it to a table saw manufacturer for a healthy fee.
“I had no desire to start my own saw company, so I called a table saw manufacturer,” Gass remembers. Gass was surprised to find, however, that the table saw maker had no interest in licensing his technology. Undeterred, he partnered with two other lawyers in his firm and hired a consultant to refine the technology, making it look more like a production saw. The consultant, Function Engineering Inc., in Palo Alto, CA, built three new prototypes, which Gass took to the 2000 International Woodworking Machinery and Furniture Supply Fair (IWF), an industry trade show.
“We figured the public would see it and ask the manufacturers to put it on their saws, and then the manufacturers would license the technology from us,” Gass says.
And the public did see it. Despite the fact that Gass rented a tiny 10 × 10 ft booth in a remote third-floor location of the Atlanta-based convention center, crowds formed. They wanted to see the hot dog demonstration. They filled the booth, then spilled out into the aisle, anxious to see “the show,” which was scheduled every 30 minutes. One industry editor told Gass he’d never seen anything like it. “He told us it looked as if we were giving away hundred-dollar bills,” Gass says.
Battle Lines Drawn Buoyed by the reaction at IWF, and by the prestigious receipt of a Chairman’s Safety Commendation from the U.S. Consumer Product Safety Commission in 2001, Gass and two colleagues from his law firm decided to pursue full-time product licensing. But within months they began to understand that the power tool industry wasn’t as excited about their technology as the attendees at the IWF show.
One CEO, traveling to Gass’s barn-based headquarters, expressed the industry’s position in terms that shocked Gass. “We sat around a little table and he said, ‘You guys have got to understand. Nobody in this industry likes you,’” Gass recalls. “‘You’ve created a huge problem here.’”
As an attorney, Gass is sympathetic with the industry position. The prospect of implementing a new technology like SawStop raises the potential of investing frightening amounts of capital to re-tool existing production lines.
“It’s not a simple issue for the manufacturers,” he explains. “They have whole product lines of saws. Once the genie is out of the bottle, there’s a huge product liability problem for any manufacturer who doesn’t have this. People will ask, ‘Why didn’t you have this on the saw you sold to us?’”
Product liability experts also hint at another reason for the industry’s lukewarm reaction to SawStop. Today’s saw manufacturers, they say, aren’t legally responsible for the horrific injuries associated with table saws. The unwritten rule applying to such situations is “use it at your own risk,” they say.
“Most of the time, legal cases are dismissed before they get to a jury because the judge agrees with the saw maker that this is an activity entered into by adults who have a general knowledge of the propensity of sharp edges to cut,” notes James T. O’Reilly, a professor of law and product liability expert at the University of Cincinnati College of Law.
Gass believes that the “use it at your risk” legal structure steals the motivation of saw manufacturers to adopt new safety technology. “What you have here is an economic disconnect,” Gass says. “The power tool companies are not paying for the injuries. You and I are paying in terms of medical premiums and workers’ comp. If the (power tool) industry had to pay, this technology would have been on those saws a long time ago.”
The power tool industry, however, has a very different view of the subject. Representatives cite a plethora of technical problems with SawStop technology, including too many “false positives” or “nuisance trips,” cost of replacement cartridges after the brake fires, and difficulties cutting conductive materials, such as moist wood. Moreover, they say, Gass is asking for an 8 percent royalty on each saw sold, a figure they describe as ridiculous.
With battle lines drawn on such issues, SawStop, LLC and the industry settled in for an adversarial relationship. In 2003, the industry, led by the Power Tool Institute, petitioned the U.S. Department of Justice’s Antitrust Division to be allowed to form a joint venture that would include Black & Decker Corp., Hitachi Koki U.S.A. Ltd., Robert Bosch Tools Corp. and others. Its goal: to develop technology for saw blade contact injury avoidance, with the possibility of creating its own skin sensing system.
Meanwhile, SawStop LLC raised the stakes again that same year, approaching the U.S. Consumer Product Safety Commission to initiate a federal mandate calling for table saws to incorporate new performance standards, which could potentially be satisfied by a technology like SawStop’s.
Opponents of SawStop’s technology — including the Power Tool Institute and Underwriters Laboratories — submitted lengthy comments to the Consumer Product Safety Commission, calling on the agency to reject SawStop’s petition. Many of the comments cited technical deficiencies and fear of a SawStop, LLC monopoly on such technology.
Changing the Status Quo Following a contentious three-year process involving technical analysis and sometimes-heated public comment, however, the agency granted Gass’s petition in June, setting into motion a series of complex legal steps. Power tool industry members have reacted coolly to the apparent setback, predicting it will have little impact.
“From a legal standpoint, it means nothing to the industry at this point, and it doesn’t change anything,” notes Daniel Lanier, an attorney who handles product liability cases for the power tool industry. “It doesn’t mean that SawStop technology is going to be required on all future saws.”
Indeed, representatives of the U.S. Consumer Product Safety Commission state that the rulemaking process requires several complex steps and “can take years.” They add that it’s rare for the agency to mandate safety standards, preferring in all cases to have industries agree on voluntary standards. In essence, experts say, industry will do its best to help create voluntary standards that would obviate the need for SawStop.
While both sides await that rulemaking process, the big saw makers continue to develop new safety technology, which they hope will meet any new standards that may emerge. Through their joint venture — which has now been together for three years — they have reportedly created an improved mechanical guard, and a blade avoidance system “somewhat like SawStop’s,” a spokeswoman says.
Gass says the joint venture is just one more battle front in a large-scale assault that’s been leveled against him by the industry.
Still, he is encouraged by the recent U.S. Consumer Product Safety Commission decision in support of his petition. The decision, he says, sets the stage for change.
“It establishes the fact that the status quo won’t work,” Gass says. “The most likely practical ramification is that attorneys for people who’ve had their fingers cut off will use this as evidence to show that the saws are defective.”
In the meantime, however, table saw accidents continue. And many of those accidents cost money for employers, as well as insurance companies. Gerald Wheeler, a Little Rock-based cabinet door maker who has had one employee saved by SawStop, says he paid out $95,000 for two other employees who lost fingers before he bought the skin-sensing saw. By purchasing the higher-cost SawStop model, Wheeler says, he saves money by not having to having to pay accident claims.
Given such successes, Gass says he will continue to produce saws. Later this year, his company plans to roll out a contractor’s model. At some point, the company also says it will extend the skin-sensing technology to circular saws, band saws, and miter saws.
For Gass, his life’s work isn’t as lucrative as it was six years ago, when he worked as a patent attorney. He and his partners, he says, now draw salaries that are about one-third of what they made back then.
Still, they plan to forge ahead, building saws that will go head to head with those of the big manufacturers. Ultimately, the company’s founders hope that consumer demand for greater safety will help their company grow and simultaneously force the industry to adopt new safety measures.
“We’re not just doing this for the money,” Gass concludes. “We’re doing this because we feel good about it.”
Injuries from Bench and Table Saws (Statistics from U.S. Consumer Product Safety Commission) A memorandum from the U.S. Consumer Product Safety Commission in June, 2006 states that “over a 10-15 year lifetime of a table saw, it would generate societal costs of $2,600 to $3,100” from blade contact injuries. Such saws typically have initial costs ranging from about $100 to $300.
The Thumb Was Still Attached Even amidst the high-pitch whine of the spinning saw blade, Carl Seymour could hear the dreaded “ping.” He’d been hit. He felt the impact in his left thumb. A 12-year veteran of professional woodworking shops, Seymour knew what it meant and instinctively wrapped his good hand around the injured digit. He held tight and sprinted to the nearest bathroom, seized with all the panic-filled emotions of the moment.
“I stood there for about two or three minutes holding my thumb, praying that it wasn’t cut off,” Seymour recalls of the accident, which occurred last March. “I saw the blood dripping through my fingers, but when I opened my hand to check it, the thumb was still attached.”
To Seymour’s amazement, the thumb was not loosely attached. It was fully intact. No bones were showing. When he wiped away the blood, he discovered the wound was little more than a paper cut, not even requiring stitches to close up.
“As soon as he opened his hand and peeked in, he started jumping up and down and hollerin’ and whoopin’ with joy,” notes Gerald Wheeler, co-founder of Cabinet Door Shop (Little Rock, AR) where Seymour works. “The saw blade had barely gone through the first few layers of skin.” Seymour’s thumb had been saved, however, not because of quick thinking or even good fortune, but because Cabinet Door Shop’s SawStop table saw sensed the difference between flesh and wood, stopped the spinning blade and retracting it back into its cabinet before the teeth could tear through Seymour’s ligaments, tendons and bones.
SawStop, LLC, developer of the technology, counts 52 such “saves,” but those 52 are minuscule when compared to the number of accidents that occur every year. The company currently has approximately 2,000 saws in the field, and hopes to sell about 3,000 in 2006.
“There’s no doubt that more people could be saved by this technology,” says Wheeler, who has seen other employees lose fingers in the past. “What’s so disheartening is that the technology is out there for the taking.” - CM
How SawStop Saves fingers In developing SawStop, inventor Steve Gass faced two key challenges: sensing flesh and quickly stopping a spinning, 4,000-rpm blade.
To sense the touch of flesh, the unit employs a signal generator to induce a 500-KHz electrical sine wave current on the saw blade. When a woodworker touches the blade, that finger “becomes part of the blade,” Gass says. An electrode adjacent to the blade serves as a sensor and sends that signal back to electronic circuitry via a wire. In the circuitry, a Texas Instruments Digital Signal Processor (DSP) with an analog-to-digital converter then digitizes the analog signal. Every 6 µsec, the DSP samples the voltage at the blade, “looking” for a characteristic drop that would indicate a human body has drawn some current off the blade. “That’s where we use our software algorithm, to look at the amplitude of the voltage as a function of time,” Gass explains.
One characteristic the algorithm looks for is a precipitous drop in the voltage as the teeth of the blade intermittently cut the skin and move through salty, wet tissue, which conducts electricity more effectively (as the conductivity rises, more current is drawn off the blade). By sensing the voltage as a function of time, the system infers electrical capacitance, and therefore determines if the blade is touching flesh.
Stopping the blade is another matter, made more difficult by the speed with which it must happen.
“You have to stop a 4,000-rpm blade in a few thousandths of a second, or it’s too late,” Gass says.
To do so, Gass employs a compressed spring, held back by a 10 thousandths of an inch fuse wire. When the DSP recognizes flesh, it signals a capacitor to send a surge of electrical current, vaporizing the fuse wire in approximately 15 millionths of a second. When the fuse wire vaporizes, it releases the spring brake, stopping the blade.
Gass says the blade typically stops in about three thousandths of a second.
“We have 52 saves,” he says. “And the vast majority of those walked away with nothing more than a tiny scratch.” - CM
Industry’s View The following is an excerpt from a letter from the Power Tool Institute to the chairman of the U.S. Consumer Product Safety Commission on June 12, 2006.
“… The fact is that each manufacturer evaluated and assessed the technology, some more extensively than others, and each independently concluded that licensing the technology was not appropriate, particularly under the terms demanded by Mr. Gass. All of the table saw manufacturers identified significant problems associated with the technology, including such things as a propensity to inadvertently activate when cutting high moisture content wood. Additionally, at the time of each company’s evaluations, the technology was completely unproven and untested; only a prototype had been produced, and it had not been subject to any real world testing over time as would be necessary before any table saw manufacturer would introduce new technology such as this.” - CM
Researchers at the University of Maryland have achieved a first in lithium-ion battery science: the development of a successful lithium-based battery using one material for all three core components of a battery -- anode, cathode, and electrolyte.
The online Bar Steel Fatigue Database for automotive design engineers has been updated for the fifth time and now contains 134 iterations, or grade/process combinations. It provides better predictability for designing parts with long-term reliability and durability.
FPGAs use programmable fabric to create custom logic, but this flexibility comes at a cost -- usually around 10 times more silicon real estate and 10 times the power dissipation. Can we really claim any FPGA is low power?
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.