Listed below are some instructions about how to build a magnetic tumbler.
As previously stated, this is not intended to be exact, step-by-step plans on how to build a magnetic tumbler, rather it is intended to demonstrate how I assembled my units. If you undertake this project, any and all risks associated with using any of the tools required will be your responsibility. Furthermore, you will be working with electricity and must have a qualified licensed electrician perform the wiring of the magnetic tumbler, and you may need a final inspection by a government agency before use. BE CAREFUL!
See the pictures and exploded views:
Cabinet assembly
1. Make a 12" x 12" x 16" high open-top box from 5/8" or thicker particleboard or plywood. Use screws and glue to assure a rigid and strong assembly.
2. Cut an opening in the back of the box for the vent grille. Size will be determined by the exact size of grille you purchased.
3. Drill a hole for the powercord in the back of the box below the vent hole.
4. Use a large hole saw or jug-saw to cut a circular hole in the front of the box the same size as the vent fan. Round the edges with a router or file.
5. Cut a hole below the vent-fan hole for the switch plate
6. Paint the box a waterproof color of your choice. I used automotive "trunk" paint because it has a bit of texture.
Switch Plate Assembly
1. Cut a metal or plastic sheet into a convenient size to hold the switch.
2. Drill the appropriate size holes for the switch, fuse holder and mounting screws.
3. Attach switch, fuse holder and power lamp (if desired) to the switch plate
4. Attach the plate to the cabinet with wood screws.
Fan Assembly
1. Measure the mounting holes on the fan
2. Drill holes in the cabinet that match the measurements taken from the fan
3. Mount the fan and fan guard with the machine screws.
Disc Assembly
1. Cut or purchase an 8" diameter circle from 1/2" thick particle board or plywood.
2. Lay out 4 equally spaced holes on a 6" diameter and drill these holes to the same size as the magnet diameter. Exercise extreme precision in this operation to assure proper balance of the disc when the magnets are installed.
3. Drill 4 small equally spaced holes through the wooden disc and through the aluminum sanding disc.
4. Using small BRASS machine screws and epoxy, attach the wooden disc to the aluminum sanding disc using the holes drilled in step 3.
5. The bushing that is supplied with the aluminum sanding disc is unsuitable for a well balanced rotating assembly. Instead, use a bronze bushing of appropriate size. Place the bronze bushing into the 1.0" shaft hole in the center of the aluminum sanding disc head and mark the location of the setscrew.
6. Remove the bronze bushing and drill a hole through it at the setscrew location and re-insert into the bore of the aluminum sanding head.
7. Slide the disc assembly onto the motor shaft and, using a longer screw the same thread and pitch as the original set screw, secure the disc to the shaft.
Motor Mounting
Mount the motor/disc assembly into the box, leaving NO MORE than 1/8" gap between the magnet mounting surface (the surface of the disc) and the plexiglas top. However, you must be careful not to allow the disc to contact the plexiglas when the force of the magnets pulls the shot-laden bowl downward. Some adjustment is necessary after complete assembly. The exact method of mounting the motor will depend upon the type of motor you have purchased.
Wiring
Wire the motor, switch, fan, lamp and fuse using solder and heat shrink tubing. Follow all accepted wiring codes and practices and before you use the tumbler, obtain an inspection by a licensed electrician.
Magnet Installation
When all the wiring is complete and tested, use epoxy to secure the magnets into the holes in the disc. The polarity of the magnets should be as follows when looking down at the disc, it is also important to arrange the magnets in a diamond shape rather than a square. Note that the two magnets with North facing up are farther apart than the two magnets with south facing up.
Be EXTREMELY careful with the magnets, they will "jump" together from a great distance with great force and will painfully pinch your hands and possibly damage the magnets.
Plexiglas Top Attachment
1. Drill at least 8 holes through the plexiglas and into the wood of the cabinet.
2. Countersink the holes in the plastic and use wood screws to attach the plastic top to the box.
3. Attach rubber feet to the bottom of the box.
Final adjustments and assembly
1. Place the plastic shot bowl with shot and water on the magnetic tumbler and, through the large hole for the vent fan, spin the disc to determine if it contacts the plexiglas top. If contact occurs, adjust the motor assembly to prevent contact but keep the distance no more than 1/8" between the magnets and the plexiglas top. Also check to make sure the magnet disc is parallel to the top. Adjust motor assembly as necessary.
2. Attach rear vent.
3. Plug into grounded, GFI protected outlet and tumble away!