Patent ID: 8438958

Claim:
A woodworking machine comprising: a support structure; a motor supported by the support structure; a blade assembly including a blade with cutting teeth, where the blade assembly is supported by the support structure and moveable by the motor, and where the blade assembly is electrically isolated from the support structure; a reaction system adapted to perform an action to mitigate injury if a person contacts the blade; and a contact detection system to detect contact between the blade assembly and a person, where the contact detection system includes circuitry adapted to generate a drive signal, to apply the drive signal to the blade assembly, and to detect a change in the electrical signal on the blade assembly due to an electrical load applied to the blade assembly, where the contact detection system is adapted to trigger the reaction system when the electrical load applied to the blade assembly is sufficient to lower the electrical signal on the blade assembly to a predetermined amplitude over a predetermined period of time, and where the contact detection system is further adapted to adjust the drive signal to try and maintain a predetermined electrical signal amplitude on the blade assembly in the presence of changing electrical load applied to the blade assembly by cutting wet wood.