Abstract: A shingle trimming tool comprises a stationary and and a movable blades with edges. When a manually operated lever is lowered, the movable blade is mounted to reciprocate towards a closed position with the edges in contact and returns to an open position. The blade moves with a sliding action in which the reciprocating edge is driven into confrontation with the stationary edge to pinch work between the blades. When the lever is raised, then the movable blade slides back to an open position. The fixed blade and a pair of matched bell cranks are supported by a frame. The movable blade is supported by the bell cranks which hold the sharp edge of the movable blade parallel to the sharp edge of the lower blade during the entire reciprocal path traversed from open to closed position and back to the open position. The lever is connected to links provides leverage to force the movable blade down into contact with the stationary blade.