I realized that this wouldn't be of much use to a lot of the people here when I posted it. However It might be something somebody could use.
A tutorial? Hmmm Its pretty straight forward.
1- Select a motor, Hvac, Blower motors work well. 1/4 hp is overkill your only spinning a disc there is very little load on the motor. I got mine off Ebay for $9.00 plus shipping. Shaft length should be 3 to 6 inches. longer means a bigger box, shorter is harder to work with when mounting the disc, It can still be done. If your motor is not already fan cooled you will need to attach a 4in 110v fan to the box. 1 is enough. (Ebay) I used a Dayton Axial fan #4c656a
2- Decide how your going to mount the motor. It will depend on the style of motor you have. Mine hangs by the studs. I used 4 pieces of angle.
3- Decide on box size. Mine is 13 inches cubed. If your motor shaft is longer you will have to make it taller. I used 1/2 inch Plexiglas because I had it left over from building my house. 3/4 plywood will work fine. The box will get wet over time as you use it so some thought on how to make it moister resistant Will be needed. Paint, caulk, etc.
4- The sanding disc, I used one from an 8in delta sander. I ordered mine from
http://www.ereplacementparts.com/disc-plate-p-86145.html $25.00 plus shipping
You will need to make an adapter to reduce the sanding disc bore from 5/8th to 1/2 in for the motor shaft size unless you have a 5/8th shaft. It will have to be drilled and tapped for 10/32nd set screws. Or find a sanding disc with a 1/2 shaft bore. You can use a 6in sanding disc. without a problem
5-Magnets, I used 4, 1.5wide x 1/2deep Magnets. 1 in x1/2 would work, I tend to over build. They cost me $20.00 for 4 plus shipping from 'Magnetsforless' on Ebay.
6- 1- On/off toggle switch heavy duty rated, 60 min. timer, power light,optional but it looks professional. A power cord. 4 rubber feet. I used a 4inch drain grill from Lowes to cover the 4in circulating fan. Qty. 2-$2.99e. 1/8 plate 4x6 to hold the Switches etc.
7- I used a Cuisinart bowl off Ebay, Any flat bottom bowl with a lid will work. I used the Cuisinart because it has a handle and a column in the middle of the bowl that helps keep the parts out towards the edge of the bowl where the action is. I made a plug for the center of the bowl out of scrap Plexiglas from the cut outs.
8- Stainless steel pins. They are available through jewelers supply but I can probably get them for you cheaper. They are the most expensive At $50.00 for 8oz. that is more than you need.
9- 1 piece of Plexiglas min. 1/4 thick for the top.
Build and assemble your box and motor bracing, hang the motor, fit the circulation fan if used, cutting a 4in hole on opposite sides. I used a hole saw but a jig saw will work fine. Fit the fan/ hole covers. Cut out a hole out to put the switch plate assembly in. Mine was 3x5.
Hanging the motor; On mine the top of the sanding disc is 3/4 of an inch below the top of the box. The magnets are strong enough you can hold the bowl 2inches over the top of the box and it still whips the pins around. The magnets ore 1/2 so you have 1/4 in of clearance between the magnets and the top of the box. Check the motor for plumb and adjust.
Making the sanding disc assembly; The magnets are held on the disc by making a plywood or Plexiglas disc the same diameter of the sanding disc. Layout your disc with a drawing program or a compass. The plate to hold the magnets should be 3/8 to 1/2 thick. I used 1/4 but there is a chance the magnets can whip out of the holes.DAMHIKT. YOU need 1 1.5 hole for each magnet and one hole for a screw between each magnet. Use a 5in diameter circle for the center of the magnets and screw holes. Exact measurements and placement are critical for the balance of the disc. Drill your holes in the holding disc using a 1.5 Forstner bit on the drill press. I cannot stress accuracy strong enough on drilling these holes.
To center the holding disc on the sanding disc. I bored a 5/8 hole in the center of the holding disc. pushing the 5/8th adapter up through both plates i drill the screw holes through both plates. I counter bored the top plate and threaded the sanding plate but you can just bolt right through both of them. the Magnets will just snugly fit in the holes and are glued/ epoxied to the sanding plate with a thin layer of glue. I used CA.
Once you have the disc made, and the motor hung check clearances and do the final assembly. I would make at least one side and the top removable to be able to work in side the box, thats what I did. The circulating fan doesn't need to run after the main motor is shut off. You will need to attach small pieces on the top around the bowl to keep it from walking off the box from vibrations.
Cleansing solutions for the tumbler. You can use any burnishing solution from places like THunderbird supply or RIO Grand supply, they make a special solution or powder you can mix or you can use COCA Cola. or what ever brand you have of cola. Pour in about 1/2 (4 ounces of Pins) cover about 1/2in with solution put in you pieces and let it do its thing. I use a micro mesh coffee filter to pour the pins/pieces/solution in to keep the pins form going down the drain. A magnet in a plastic bag to pull the pins off the pieces is handy. Pass the magnet in the bag around the polished pieces and then pull the bag off dropping the pins back in the bowl.
Thats about it. Good luck and contact me is you have any questions.
MIke