Apparatus and method for detecting dangerous conditions in power equipment

Abstract

A machine such as a saw, jointer, planer, etc. is disclosed. The machine has cutting tool, a direct drive mechanism configured to move the cutting tool, a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, and a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system. An electrical signal is imparted on the cutting tool, and the signal is used to determine the occurrence of the unsafe condition. The direct drive mechanism is electrically isolated so that the electric signal may be imparted on the cutting tool. The electric isolation may be achieved through configurations such as insulated bearings, a substantially non-conductive housing, and a substantially non-conductive coupling joining two shaft portions.

1 . A saw comprising:
 a circular cutting tool adapted to spin;   at least one motor configured to move the cutting tool;   a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, where the detection system is adapted to impart an electrical signal on the cutting tool;   a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system; and   means for electrically isolating the cutting tool so that the electric signal may be imparted on the cutting tool.