A safety system is provided for a power tool having a motor-driven cutting blade, a safety mechanism operable by a controller to stop and/or move the cutting blade and a blade guard. The safety system includes an electrically active surface provided on the blade guard that is configured to change an electrical characteristic in response to contact between the body of an operator and the active surface. An active surface controller is operable to provide electrical power to the electrically active surface, to generate a signal in response to the change in the electrical characteristic, the signal indicative of an unsafe condition, and to transmit the signal to the controller for the safety mechanism.

The disclosure relates to a circular saw, in particular a hand-held circular saw, having a housing and a drive unit, at least some sections of which are arranged in the housing and with which a tool holder for an exchangeable saw blade is associated. The drive unit is designed to rotationally drive the exchangeable saw blade about an associated axis of rotation. In the circular saw, a blade guard is associated with the exchangeable saw blade. The blade guard is mounted in the housing for rotation about the associated axis of rotation and extends around a cutting point of the exchangeable saw blade at least during a sawing operation in such a way that contact with the cutting point can be at least substantially prevented.

The disclosure relates to a circular saw, in particular a hand-held circular saw, having a housing and a drive unit, at least some sections of which are arranged in the housing and with which a tool holder for an exchangeable saw blade is associated. The drive unit is designed to rotationally drive the exchangeable saw blade about an associated axis of rotation. In the circular saw, a blade guard is associated with the exchangeable saw blade. The blade guard is mounted in the housing for rotation about the associated axis of rotation and extends around a cutting point of the exchangeable saw blade at least during a sawing operation in such a way that contact with the cutting point can be at least substantially prevented.

Systems and methods for braking a power tool using a stamped brake resistor. The power tool includes a motor, a trigger configured to be actuated, and a brake switch coupled to the motor. A brake resistor assembly is selectively coupled to the motor via the brake switch and includes a stamped brake resistor. The stamped brake resistor includes a terminal portion and a resistive portion. The resistive portion includes a planar serpentine path. A controller including an electronic processor and a memory is coupled to the trigger, the motor, and the brake switch, and is configured to control power delivered to the motor based on a position of the trigger, determine to brake the motor during operation of the motor, and activate, in response to determining to brake the motor, the brake switch to connect the stamped brake resistor to the motor.

Systems and methods for braking a power tool using a stamped brake resistor. The power tool includes a motor, a trigger configured to be actuated, and a brake switch coupled to the motor. A brake resistor assembly is selectively coupled to the motor via the brake switch and includes a stamped brake resistor. The stamped brake resistor includes a terminal portion and a resistive portion. The resistive portion includes a planar serpentine path. A controller including an electronic processor and a memory is coupled to the trigger, the motor, and the brake switch, and is configured to control power delivered to the motor based on a position of the trigger, determine to brake the motor during operation of the motor, and activate, in response to determining to brake the motor, the brake switch to connect the stamped brake resistor to the motor.

Fast-acting and low-inertia actuators useable in various applications where a high force must be applied very quickly are disclosed. Power tools with detection systems configured to detect a dangerous condition between a person and a cutting tool are disclosed. In power tools, for example in a woodworking machine, a fast-acting and low-inertial actuator as disclosed herein can be used to retract a blade upon detection of a dangerous condition by a detection system. The actuator includes a charge of pressurized fluid and one or more electromagnets to selectively retain or release the pressurized fluid.

A holder assembly for a circular saw tool includes a blade having a bore. The blade is mountable to a free end of a rotatable shaft or of the tool through the bore. The blade is further adapted to be held in a pressing manner between an inner flange and an outer flange on the shaft. The holder assembly is comprised of at least one depression formed on a circumferential surface of the free end of the shaft, and at least one clutch member (or dogs) paired and mounted about the at least one depression, and located between the bore of the blade and the shaft. The holder assembly provides improved gripping while safety or emergency braking.

A sawing apparatus can have a drive shaft that is rotatable about a central axis for rotationally driving a saw blade. The apparatus includes an electrical rotary feedthrough for the electrically conductive connection of the drive shaft to a connection assembly. The electrical rotary feedthrough includes a first component having a contact section that tapers in the direction of a second component and the shell surface of said contact section forms a first contact surface. The second component has a receiving channel that extends along the central axis and the side surface of the receiving channel forms a second contact surface. The first contact surface lies against the second contact surface in sections. The receiving channel and the tapering contact section has a clearance for ruling out a purely axial abutment of the components. In addition, an electrical rotary feedthrough for a sawing apparatus, is described.

A sawing apparatus can have a drive shaft that is rotatable about a central axis for rotationally driving a saw blade. The apparatus includes an electrical rotary feedthrough for the electrically conductive connection of the drive shaft to a connection assembly. The electrical rotary feedthrough includes a first component having a contact section that tapers in the direction of a second component and the shell surface of said contact section forms a first contact surface. The second component has a receiving channel that extends along the central axis and the side surface of the receiving channel forms a second contact surface. The first contact surface lies against the second contact surface in sections. The receiving channel and the tapering contact section has a clearance for ruling out a purely axial abutment of the components. In addition, an electrical rotary feedthrough for a sawing apparatus, is described.

A power tool that includes a housing, a motor, an end effector, an electrostatic clutch assembly, and a control circuit is provided. In a first mode of operation, the control circuit causes a first voltage to be applied to a first electrode and a different second voltage to be applied to a second electrode, generating a first attractive force between the first and second electrodes, which causes an output member to rotate together with an input member when a torque on the output member is less than or equal to a first threshold value and which causes the output member to rotationally slip relative to the input member when the torque on the output member exceeds the first threshold value, interrupting torque transmission from the input member to the output member.