Several embodiments of tachometers generators for use in controlling the speed of electrical motor driven tools. In each embodiment a toothed rotor (28, 52, 72, 92, 122) is fixed for rotation with the motor armature shaft (23, 53, 73, 93, 124) and a sensor (31, 55, 75, 96, 126) is juxtaposed to the rotor. The sensor is comprised of a core (32, 56, 76, 98, 127) having a first end portion (33, 57, 77, 99, 128) juxtaposed at a first location relative to the rotor and a second end portion (36, 58, 78, 101, 129) that is juxtaposed to the rotor at a second, spaced location. A permanent magnet (37, 59, 79, 102, 131) is interposed between the second end portion and the rotor with one of its poles aligned with a second end portion and the other of its poles aligned with the rotor. A coil (38, 61, 81, 103, 132) is wound around an intermediate portion (34, 62, 82, adjacent 99, adjacent 128) of the core so that a voltage will be generated in the coil by the alternating magnetic flux passing through the core during rotation of the rotor, which voltage is indicative of the speed of the armature shaft. The compact construction facilitates installation in close places and the device provides a strong signal and exhibits a high signal to noise ratio.
A sander can include housing, and a motor assembly in the housing. The motor assembly can include an output member. A platen can be driven by the output member. A user feedback assembly can be coupled to the housing and have a sensor assembly, a controller and an indicator. The sensor assembly can be configured to sense a parameter that is related to a magnitude of a force transmitted between the platen and a workpiece and generate a signal in response thereto. The controller can receive the sensor signal from the sensor assembly and control operation of the indicator in response thereto.
A sander can include a housing and a motor assembly in the housing. The motor assembly can include an output member. A platen can be driven by the output member. An indicator can be disposed on the housing and include a light source. A semi-transparent lens can be disposed generally over the light source. The semi-transparent lens can have a plurality of prisms defined thereon and configured to disperse emitted light from the light source. The semi-transparent lens can include a chimney formed thereon. According to additional features, the indicator can include at least a first and a second light source. The chimney can be aligned with the first light source for directing emitted light from the first light source therethrough.
A sander can include a housing, an indicator coupled to the housing, and a motor assembly in the housing. The motor assembly can include an output member. A platen can be driven by the output member. A DC generator can be driven by the output member. The DC generator can generate an output signal with a voltage that is related to a rotational speed of the motor. A controller can operate the visual indicator based on the voltage of the output signal. According to additional features, the DC generator can provide electrical power to operate the indicator. An electric power input can be electrically coupled to the motor. The visual indicator can be electrically isolated from the electric power input.
