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How to Build a Magnetic tumbler


#1

I can’t offer measured drawings and the like, but here’s how you do
it. You need:

  1. “Washing machine” motor of 1725 or 1750 rpm.

  2. 5"-6" aluminum sanding disk, like lapidaries use, with a shaft
    size to fit motor.

  3. 1/2" plywood or particle board circle the same size as the sanding
    disk.

  4. 4-Neodymium Iron Boron disc magnets 3/4" or 1" diameter by 1/2"
    thick.

  5. 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…


#2

Hello Deborah,

Re: the magnetic tumbler. I have had a change of servers and email
addresses, but the original plans I posted a few years ago are
available here:

http://rchristopher.com/MagTumbler/MagneticTumbler.htm

If you have any questions, please feel free to email me.

Regards,
Bob


#3

deborah, the and drawings on how to make the magnetic
tumbler are online at :

http://majorleagueduning.com/Stuff/Bob/MagTumbler/MagneticTumbler.htm

I made one using his and it works great. Hint: the
magnets are available an ebay now, much less expensive. search under
rare earth magnets, or neodumium magnets.

good luck


#4

Yes, the posts with the links to plans are the very tumbler I
described in my mess. I had lost track of where they are - If you
build it well (balance, etc.) it will work like a champ…


#5

I’m not usually one to make a piece of machinery, tools yes, but
this has some interest.

I’ve always had space limitations which is why the commercial units
have been my goal and the smaller commercial units are pretty quiet.
I assume that the hand built ones are quite a bit louder? Are they
more powerful? Can you load up a lot more media? What’s the limit in
weight and in bowl size for the hand built units?

I recently saw that Gesswein is selling mag. tumblers that utilize
regular ceramic media (in modified bowls). It would seem to me that
the size of the media, stuffed into a small bowl like that wouldn’t
be very efficient, but if it works it would be very useful. Do you
think a bowl could be made that could utilize standard ceramic media
in the hand built units, too? I assume that if you could, and if the
unit is generally more powerful than the small commercial units that
you’d probably be able to use a larger bowl. I’d love to see how the
bowl works in the commercial unit, but I’ve never seen it live.

Larry


#6

I have noticed that Gesswein now has a bowl where the magnets drive
a rotor inside the bowl, which will drive other media - Raytech, I
believe. Otherwise, the media has to be steel, because the magnets
are “grabbing” it through the bottom of the bowl. As far as “Store
bought or homemade” and such. My first tumbler was the plans that
have been posted here. I always have a stray motor, and a woodpile -
and I have woodworking tools (tablesaw…). I also had an aluminum
sanding disk laying around. So, for something like $50, I built a
tumbler with the capacity of a $3500 machine. I’ve been making
smaller tabletop versions lately - store bought would be the
$400-$600 machines. They cost me something like $50-$75 depending.
Plus labor and all, of course. They are real handy - ours is running
right now.