Power tool with force sensing electronic clutch

A power tool comprising:

• a housing;
• a motor disposed in the housing;
• a transmission disposed in the housing and coupled to the motor;
• an output end effector coupled to the transmission;
• a control circuit for controlling power delivery from a power source to the motor;
• a force sensing electronic clutch including a force sensor that senses a reaction torque transmitted from the end effector to at least a portion of the transmission and causes the control circuit to initiate a first protective operation when the sensed reaction torque exceeds a first threshold torque value;
• and
• a current sensor that senses an amount current delivered to the motor,
• wherein the control circuit uses a current signal from the current sensor to automatically re-calibrate the first electronic signal from the force sensor, during a period when the control circuit determines that the current signal by itself is a good indicator of output torque.

A power tool comprising:

• a housing;
• a motor disposed in the housing;
• a transmission disposed in the housing and coupled to the motor;
• an output end effector coupled to the transmission;
• a control circuit for controlling power delivery from a power source to the motor;
• a force sensing electronic clutch including a force sensor that senses a reaction torque transmitted from the end effector to at least a portion of the transmission and causes the control circuit to initiate a first protective operation when the sensed reaction torque exceeds a first threshold torque value;
• a current sensing electronic clutch including a current sensor that senses an amount current delivered to the motor, and a controller that causes the controller to initiate a second protective operation when a value from the current sensor exceeds a current threshold value that corresponds to a second threshold torque value.