Abstract: A shot blast machine for cleaning workpieces that includes two tumbler sections and at least one blast wheel for impelling abrasive particles. Both tumbler sections have a surface with an ingress and an egress for supporting and tumbling the workpieces under the path of abrasive particles. Though horizontally adjacent, the two surfaces are vertically displaced relative to each other. The vertical displacement of the surfaces forms a step to induce an additional tumble of the workpieces as they tumble from the egress of the first tumbler section to the ingress of the second tumbler section, thereby encouraging the shot blasting of every surface on the workpieces in a timely manner. The degree of tilt of the surfaces is selectively adjustable, thereby allowing substantial control over the duration of the cleaning cycle.