How to Make a Vibrating Parts Tumbler

Fabricate a steel frame to hold two conveyor belt rollers parallel to each other, 6 inches apart. Use flat cold rolled-steel stock. Make 90-degree bends 3 inches from each edge, forming a goal-post profile. Drill holes in the upright flanges, 1/4 inch from the top edge, 6 inches apart, on both sides to hold the conveyor axles. The holes need to be the diameter of the threaded roller axles.

Install one of the conveyor rollers into the first set of holes and thread nuts onto each end of the threaded axles.

Expand one of the remaining holes large enough to fit a doughnut-shaped bearing with an inside diameter the same size as the threaded axles. Press the bearing into the hole. Tack weld the bearing in place with several quick trigger pulls of a MIG welder around the perimeter of the bearing.

Slide the second roller through the hole on one side and through the bearing on the other. Now, tack weld the bearing built into the roller nearest the bearing you installed in the frame. Use the same quick trigger pull technique in six or eight spots around the edge of the roller. Locking the roller's bearing in place means you can spin the roller by spinning the axle. Because the axle rests in a bearing in the frame, it can be spun for long periods without creating significant friction or wear.

Build a coffee can tumbler with an agitator. Use a tin coffee can with a plastic lid. From another coffee can, cut a vertical strip of tin 1 inch wide. This will be your agitator, similar to an agitator in a washing machine. Fold the strip down the center and bend it at a right angle into a piece that from the bottom or top looks L-shaped, with 1/2 inch on either side of the fold. Apply a thin layer of J.B. Weld epoxy to one side of the agitator. This epoxy lets you glue metal to metal with a very strong bond. Install the agitator by pressing the epoxied surface against the inside of the coffee can tumbler's wall. Let the epoxy dry overnight. The agitator will churn the media or shot the same as a vibrating action.

Fill a the coffee can with shot or media and the parts you want to peen. Seal the plastic lid on the coffee can.

Wrap the can in heavy rubber bands or even vacuum cleaner drive belts. The rubber bands will provide cushions for the can to roll on.

Tighten the chuck of a hand drill to the section of threaded axle protruding through the frame to power the rollers.

Set the can so it is cradled between the two rollers. Turn the drill on. Engage the drill's trigger lock and let the parts tumble.