How it works Edit

" Stopping the blade...would require a two-part process. First, [Gass] needed a brake that would work quickly enough when it came into contact with a woodworker's hand. Next, he had to design a triggering system that could differentiate between finger and wood. Given the speed of the blade, it would have to stop in about 1/100 of a second — or at about an eighth of an inch of rotation after making contact. Any further, and the cut would be so deep that the device would be useless. To stop the blade this quickly would require about 1,000 pounds of force to decelerate the blade in 10 milliseconds. ” — Inc.magazine in 2005.[1] SawStop's saws apply a small amount of electric voltage to the blade of the saw. The current through the blade is continuously monitored. If the saw detects a change in this current (as would occur if a hand or other body part came into contact with the blade) an automatic braking system is activated, forcing an aluminum brake block into the blade. The saw stops within five milliseconds, and angular momentum lowers the blade into the table. The operator suffers a small nick instead of an amputation or other more serious injury.[2] The design takes advantage of the difference in "electrical conductivity" (similar to a GFI circuit) between wood and flesh.[3]