I can’t offer measured drawings and the like, but here’s how you do
it. You need:
-
“Washing machine” motor of 1725 or 1750 rpm.
-
5"-6" aluminum sanding disk, like lapidaries use, with a shaft
size to fit motor. -
1/2" plywood or particle board circle the same size as the sanding
disk. -
4-Neodymium Iron Boron disc magnets 3/4" or 1" diameter by 1/2"
thick. -
Wood for a box, various tools - a wood drill bit the size of the
magnets, and a container for the shot and work.
I’ll discuss the magnets later, but all you do is lay out the plywood
circle very carefully so that you can bolt it onto the sanding disk
on the exact same center. Then you drill it through in four equally
spaced spaces to the size of your magnets, probably 1/2 way across
the radius, or so the holes are inside the circle of the container
you will use, bolt the wood to the disc, put the magnets in the holes
- they should fit tightly, but I’d recommend a little epoxy for
insurance. Then build a box out of plywood so the motor can be
mounted shaft up, with a top made out of 1/4" plexiglass or heavy
aluminum. You want the disc to be about 1/8" or 3/16" below the top,
so the motor height needs to be adjusted accordingly. It’s also
useful to put some sort of brackets or wood blocks on top so the
container won’t walk - anything that will keep the bottom of it on
center. Put your container on top, put pins, water, tumbling soap and
work, turn it on and voila"! Magnetic Tumbler!! There are some issues - like heat dissipation, and obviously the balance of the rotor is
important, which is your skill at layout and drilling, but I did that
and used it for a few years. Neodymium Iron Boron (NdFeB or “Rare
Earth Magnets”) magnets are the most powerful magnets on earth. They
are incredibly powerful, and the larger they are the more dangerous
they are. If you got a big one and walked into the kitchen, knives
would come flying at you. A very large one will alter a TV screen if
you walk into the room. 1" x 1/2" ones are manageble, but they will
pinch you real hard. If you got them apart, put your finger between
them and nudge them till they jump -broken finger. If and when you
get them, you’ll see I’m not exaggerating. To get them apart, don’t
try to pull them, put one on a counter top and slide the next one off
by pushing down on it. Anyway, you’ll see, but don’t take them
lightly. If you buy them through channels, one 1" magnet might cost
you $50. If you search EBay, you can get 4 of them for $20 or so. Get
N38 or N40 if you can - that’s the power rating. There are lots of
dealers there, just search for “rare earth magnets” or
neodymium. And be careful with them.
when you put the magnets on your rotor, alternate the poles - so
you’ll have, with 4 magnets, 2 North and 2 South. That gives the
swirling action…