Abstract: The vertically reciprocal upper blade assembly of a sheet metal squaring shear is activated in a substantially vertical path past a fixed lower blade by means of one or more reciprocal rotary hydraulic actuators. The output drive shaft of the hydraulic actuator(s) is connected to one or more drive straps by an eccentric cam which is keyed to the drive shaft and rotatably received within the straps. The horizontal gap between the upper blade and the lower blade is precisely controlled by suspending the blade supporting gib bracket from pins on the side walls of the apparatus housing and adjustably connecting the gib plate to the pins by eccentric cams. The gib mounting system also provides for adjusting the angle of the upper blade with respect to the lower blade. An improved hold down assembly limits the stroke of the hold down pins to maintain a slight clearance between the hold down pins and the bed surface at all times.