Abstract: A chopper for collated sheets of paper having a fixed blade and a pivotally movable blade for effecting scissors like chopping action. An electric motor drives a flywheel which is connected through a clutch mechanism to a crank arm which is in turn connected to the chopping blade. The clutch mechanism normally holds the chopping blade stationary until an electrical signal is sent to actuate the clutch permitting a single reciprocating movement of the chopping blade. A magnetic switch and time delay mechanism are provided to detect jamming of the chopping blade, and if jamming is detected, the motor is deactivated.