Abstract: Two sheets of deformable material are securely fastened together without the use of adhesives, separate rivets or fasteners by forming a closed end cylindrical projection on the upper surface of the first sheet, placing the second sheet having an aperture over the first sheet, the aperture receiving the projection, and deforming the projection in the aperture to produce a tight friction fit and form a lip which overlaps the exterior rim of the aperture to limit its enlargement. In a preferred embodiment two plates are fastened together to form a rotor by striking the projection with a die having an annular groove forcing one part of the projection into the aperture and forming another part of the projection into the lip.

Abstract: In a stock-piercing punch mechanism which includes a base having a punch-receiving bore, a punch having a stock-piercing tip positioned for reciprocal movement in said bore, and a cam trigger pivotably mounted on said base which is adapted to receive a stock-piercing force from a press ram or the like to cause the trigger to pivot and to transmit the force to the punch to move the punch out of the bore to pierce properly positioned stock, the improvement which comprises, a lubrication reservoir located in the base adjacent the punch so that as the punch moves in the bore it picks up and distributes the lubricant to reduce frictional wear of the punch and the bore. In the preferred embodiment the punch is removably attached to a punch plate positioned within the punch mechanism so that the punch can be readily removed and replaced with other punches having the same or different shape and size stock-piercing tips.