September – Sharp Thinking and Cutting Edge Technology

By Tony Shepley,

Some years ago, we learned of a new product on the market that made remarkable safety claims. The inventor had tried to market his new technology to all of the major players in the industry and they all turned him down. He then started his own company and began production of his own units, incorporating this new technology into them. This product is called SawStop.

The concept behind SawStop is to run a small current through the arbor and blade of the saw and to use Ground Fault Interrupter technology to sense contact of a hand or finger with the saw blade. A powerful spring drops the blade below the saw table and fires it into a block of aluminum. This all takes place in less than 5 milliseconds, which stops the saw blade so abruptly that a 10” blade makes only 1/8” of rotation after contact with human flesh! The resulting nick to the skin is equal to just a paper cut! The sensitivity is so precise that the grounding effect of a human body part is detected in 25 micro-seconds (25 millionths of a second). Incredible!

We have done a number of demonstrations here in our shop using a hot dog to simulate a finger to test the system and to show the benefits. I must say I always wondered about the accuracy of a hot dog in representing a finger. Steve Gass, the inventor of Saw Stop, who is a patent attorney, amateur wood worker, and also has a doctorate in physics, knew early on that others might have the same doubts. In 2000, after numerous hot dog tests, he took the plunge himself and put his own finger into the whirling blade of an early prototype Saw Stop unit. Even the somewhat crude-by-today’s-standards prototype stopped as designed. Talk about putting your money where your mouth used to be! It worked and Steve Gass still has all 10 fingers to this day.

Table saws cause an average of 10 finger amputations per day in the United States and the cost of these amputations is calculated to run close to $2 billion dollars per year. Steve Gass was turned down by every major manufacturer to whom he took this technology. He came close to a licensing agreement with Ryobi, but the agreement got bogged down in the fine print and after six months of back and forth, negotiations ceased. Several liability suits have been filed against saw manufacturers, claiming they could have used the technology to make their products safer but chose not to. The Power Tool Institute (PTI)  which  represents a large number of table saw manufacturers, has lobbied against SawStop technology on the grounds of increased unit cost (up to 25% more expensive than a standard saw) and their being prone to false trips when cutting wet or green wood. PTI claims that SawStop technology will cause users to become careless and over confident because they have a “sense of security”.

As the owner of multiple SawStop units, we can safely say that no one ever argues the cost of a saw when it saves their fingers, and one finger is more expensive than three SawStops. As far as people feeling over confident, I can tell you that one of the safest wood workers I know came to me a few years back and showed me a tiny nick in his finger and said, “Today, I was the hot dog and SawStop definitely saved my fingers.”

The patent rights to SawStop expire in 2021. In the meantime, the government is holding hearings to determine whether SawStop technology should be required on all new table saws. The PTI is lobbying hard to block the adoption of any legislation requiring the use of SawStop technology and companies like Bosch have sued (unsuccessfully) to have the SawStop patents invalidated. Speaking for Shepley, I can say we won’t use a non-SawStop table saw and we look forward to the adoption of their technology into other tools. We applaud Steve Gass for his out-of-the-box thinking and celebrate how many digits he has saved and will save in our industry. For more information, check out


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