Abstract: A controller for stopping a punch press when a stock material becomes jammed, includes: translating means for converting the motion of the stock material exiting from the punch press to rotational motion of rotating means which is operatively associated with said translating means, and a movable element, operatively associated with said rotating means. The rotational motion of rotating means produces centrifugal force which keeps the movable element in an operating position. As the stock material buckles or becomes jammed in the press, the motion of the exiting stock material ceases, causing a decrease in and/or subsequently elimination of the angular velocity of the rotating means and therefore a decrease in the magnitude of the centrifugal force. When the centrifugal force diminishes by a predetermined amount or is entirely eliminated, the movable element moves from the operating position to stopping position.