Making Rare Earth Magnetic Feet

I read a few threads over on stopmotionanimation.com about tie-downs vs. magnets (if you search “magnets” on the message board, over 100 threads come up — it’s quite a debate!)  I also chatted with a couple stopmo animators about their preference for magnets.  Many people on the stopmo forum prefer tie-downs…  though I respect their advice, I decided not to go that route.

The main reason for my choice of using rare earth magnets can be explained by this one picture:

Not the metal button shank… but the floor.  I put a lot of work into the floor of my set, and there’s simply no way I’m tearing it apart with little holes.  I thought of using magnets only when you can see the floor in a shot, and using tie-downs for everything else on scrap pieces of wood clamped to the floor, but what’s the point of overcomplicating things?  In the end I just put my faith in the magnet system.  I can’t be 100% sure that it will work, but the animator friends that I spoke with use (and love) rare earth magnets, and gave me solutions to some of the problems raised on stopmoanimation.com debates.  As a safeguard I also built the puppets to have a removable bolt in their upper backs, in case they need upward support while walking (and I’m pretty sure they will).

Anyhoo, here’s what I’m doing with the feet:

I used:

  1. 5-minute epoxy
  2. 1/16″ armature wire
  3. very flexible and durable 22-gauge silver wire, used for jewelry making
  4. 1/8″ x 1/8″ and 1/4″ x 1/10″ rare earth magnets (one of each per foot)
  5. 1/4″ diameter heat-shrink tubing pieces

I got a whole bunch of magnets from Lee Valley.  They have a great rare earth collection, as well as a handy guide to using them.  (Those things are strong! You can actually hurt yourself handling the larger magnets… as I found out.  So it helps to read the guide!)  I used 2 magnets in each tiny foot — hoping that Sabela will still be able to bend her foot in the middle while walking.  There’s one 1/8″ by 1/8″ magnet in her toe, and one 1/4″ by 1/10″ magnet in her heel.  Her feet are so small that there’s only about a 2mm gap between the 2 magnets, so it might be tough to bend her foot in the end, but at least it will still bend a little.  I might need a shot where she gets up on tip-toes, so I’d really like her foot to have some flexibility.

  1. I formed the armature wire into a loop in the middle, shaping the equal ends smooth and flat.  The loop is just large enough for the 1/8 x 1/8 inch magnet to fit into, and the entire piece of wire, when folded in half like this, is about 3 inches longer than the length of the puppet’s leg.  Then I epoxy the magnet in place at the end of the loop, making sure it’s facing the right way (all magnets need to be consistent with their direction, so they pull rather than repel each other.)  When the epoxy’s dry, I squeeze the loop tightly around the magnet with pliers.  The magnet is flush with one side of the armature loop — this flush part will be the base of the foot.
  2. Then I bend the wire at a 90º angle in the shape of the foot.  I measure the length of the foot and test to make sure the plaster mold can close around it before continuing.
  3. The second magnet gets epoxied to the heel of the foot, fitting into the corner groove made by the wire.  Again, the magnetic force has to be facing the same way as the small magnet that’s in the toe.  (I usually put dots on the “tops” of the magnets with marker so that I know which way’s which.)  Epoxying this one in place is really tricky — the magnet will want to flip over onto the other magnet.  So basically I need to hold it firmly in place by hand until the epoxy is dry… which can take a while.  There’s no way to clamp it, unless you have a non-metallic clamp… all the clamps I have attract the magnet, making it impossible to clamp in the right position.  (If I figure out a better way, I’ll update this post…)
  4. I then cut a piece of the heat-shrink tubing to the length of the foot, and slide it over the foot.  This is extra insurance that the magnets are held firmly in place.  I heat up the tubing on the stove, turning the burner on high and holding the foot up close to it until the tubing shrinks down to a tight fit over the foot.  This stuff is great, because it stays flexible and allows the foot to bend, but is strong enough to hold the magnets in place.

So with the 2 magnets in place in each foot, the legs will stand up (even with such tiny feet!) on their 1″ x 1/8″ magnetic disc pedestal.  I’ll do another post on how I finish off the legs, and make the magnetic base, another time…  Oops, the 22 gauge fine wire listed above gets used in the next stage, when I add more wires to the legs.

4 thoughts on “Making Rare Earth Magnetic Feet

  1. justin rasch

    Neat o!

    I am really curious to watch your work with the magnets.
    Thanks for the info.

    I have always wanted to know how strong they were and if they would cause problems in complex animations.

    jriggity

    Reply
  2. stephanie dudley

    They’re super strong! I was impressed. The problems I read about were: the 2 feet repelling each other (which they do, very slightly, I don’t think it’ll be a problem) and the feet snapping down to the floor once they get too close to the base magnet. To prevent the latter from happening, you could stack up the thin disc magnets gradually away from the floor, removing them one at a time as the foot gets closer. This works if the character needs to jump, too. (Stack magnets beneath the feet, removing them one at a time.) Shoot a clean plate of the background without the magnets or puppet, then paint the stacked magnets out with that BG plate in post.

    All this is theory though for me at this point — I still have to try it all out with a complex animation. I’ll let you know how it goes!

    Reply
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