SawStop table saws detect contact with skin, stopping the blade and removing it from the table surface in less than five milliseconds. SawStop is an American table saw manufacturer headquartered in Tualatin, Oregon.
An oscillator generates a 12-volt, 200-kilohertz (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.
The blade carries a small electrical signal.When skin contacts the blade, the signal changes because the human body is conductive.The change to the signal activates the safety system.
An aluminum brake springs into the path of the blade.The blade comes to a complete stop and power to the motor is shut off.After the blade comes to a stop, the blade’s angular momentum drives it beneath the table, removing the risk of subsequent contact.All of this happens in less than 5 milliseconds.
Resetting the saw yourself is easy. Simply inspect the blade (and change if damaged) and replace the brake cartridge, and your saw is operational.The entire process takes 90 seconds and you’re back to work.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.