Abstract: A reciprocating saw blade having a shank with a longitudinal axis which extends from one end of the blade to the other end of the blade and a transverse axis which extends across the width of the blade. A cutting edge is located along one or both longitudinal edges of the shank of the blade, a concave side wall extends along the transverse axis of one side of the blade, a convex side wall extends along the transverse axis of the other side of the blade and the curvature is around the longitudinal axis.

Abstract: Disclosed is an improved centrifuge apparatus for separating substances of varying density and a method of controlling the speed of a rotor of the centrifuge apparatus. A vent-view port is mounted for in-out adjustment within an access aperture formed in a lid of the centrifuge apparatus so as to provide for selective opening of vent holes formed in the vent-view port. In addition to venting, the vent-view port has a sensor mount with a transparent window for receiving a tachometer probe for rotor speed monitoring. Additionally, a desired centrifugal force and a desired accumulative centrifugal force can be entered by a human operator. A control unit adjusts the rotor speed and operational cycle time to meet the inputted desired force values while displaying the actual accumulative centrifugal force at the end of the operation cycle.