An acrylic end cap with upper shaft bearing bracket and vacuum port was fit snugly onto the upper cylinder end. A vacuum aspirator hose was attached to the vacuum port. A lower bearing bracket was mounted below the lower cylinder end. The rotor shaft, which was supported by the bearing brackets, was constructed of 10-mm o.d. hollow steel tubing 37 cm in length with 6-mm diameter bearing shafts brazed to each end