| CPC B25C 1/041 (2013.01) [B25C 1/047 (2013.01); B25C 1/06 (2013.01); B25C 7/00 (2013.01); B23Q 11/0092 (2013.01); B25C 1/008 (2013.01); B25D 11/00 (2013.01); B25F 5/00 (2013.01); H02P 29/0027 (2013.01)] | 20 Claims |

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1. A powered fastener driver comprising:
a housing;
a cylinder within the housing, the cylinder containing a pressurized gas;
a piston within the cylinder and moveable from a top-dead-center position to a bottom-dead-center position;
a driver blade moveably coupled to the piston for driving a fastener into a workpiece, the driver blade having a plurality of teeth defining a predetermined number of edges;
a lifter configured to sequentially engage the teeth for returning the driver blade from the bottom-dead-center position toward the top-dead-center position;
a drive unit configured to provide torque to the lifter, causing it to rotate;
a sensor configured to detect an edge of one or more of the plurality of teeth; and
a controller in communication with the drive unit and the sensor, the controller configured to:
count a number of edges detected by the sensor,
compare the number of detected edges to the predetermined number of edges, and
stop the drive unit when the number of detected edges is less than the predetermined number of edges.
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