Protect Your Business With SawStop

SawStop is an American table saw manufacturer headquartered in Oregon. The company was founded in 2000 to manufacture table saws that feature a patented automatic braking system that stops the blade upon contact with skin or flesh. This aims to minimize injuries that are relatively common when working with normal table saws.

How it works

The blade stops in less than five milliseconds, while angular momentum retracts the blade into the table. The operator suffers a minor injury instead of a serious one. The design takes advantage of the difference in conductance and capacitance between wood and flesh.

An oscillator generates a 12-volt, 200-(kHz) pulsed electrical signal, which is applied to a small plate on one side of the blade. The signal is transferred to the blade by capacitive coupling. A plate on the other side of the blade picks up the signal and sends it to a threshold detector.

If a human contacts the blade, the signal will fall below the threshold. After a signal loss lasting for 25 microseconds (μs), the detector fires. A tooth on a 10-inch circular blade rotating at 4000 RPM will stay in contact with a fingertip for about 100 μs. The 200-kHz signal will have up to 10 pulses during that time and should be able to detect contact with just one tooth. When the brake activates, a spring pushes an aluminum block into the blade. The block is normally held away from the blade by a wire, but during braking an electric current instantly melts the wire, similar to a fuse blowing.

Even with these safety features, the SawStop is still a dangerous machine, and must be used with great care.