Ring magnet in a stir plate?

[drthrob]

I am in the process of building a stir plate with a cigar box and a computer fan, but a thought occurred to me. I was originally going to harvest a magnet from a hard drive, but stopped when I realized I didn't have the Torx wrench to do so and also found that I had several rare earth ring-shaped magnets from another project. I was about to attach these to the fan when I realized that the poles are on opposite sides of the ring and this might cause problems if I was wanting to move a bar with two poles above it. Can anyone tell me whether or not this would work? My homebrew store was out of bar magnets and the ones I have ordered do not arrive until Friday. Thoughts?


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[WayFrae]

If the poles are on opposite sides of the magnet (like the heads and tails side of a coin) then it won't work for the stir plate. You would need both the poles to be on each side of the magnet, if that makes sense.

 

[drthrob]

If the poles are on opposite sides of the magnet (like the heads and tails side of a coin) then it won't work for the stir plate. You would need both the poles to be on each side of the magnet, if that makes sense.

That is what I figured. However, magnetic field diagrams I have found online seem to make it more complicated than that. On second think-through, I will probably wait until Friday and just see how the stir bar responds.


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[drthrob]

If the poles are on opposite sides of the magnet (like the heads and tails side of a coin) then it won't work for the stir plate. You would need both the poles to be on each side of the magnet, if that makes sense.

Solution: break ring magnet in half, flip one half. Glue to fan, reassemble. Works like a charm.


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[Stealthcruiser]

^^^^^^^

What he said.

 

[drthrob]

I should caution two things when trying this:

1. These magnets tend to be brittle, so I put it half in a vise and then used even pressure to snap the other half off. It resulted in a pretty clean break.

2. Don't hit the magnet. Sharp impacts have a way of removing the magnetic field. Also, see #1 re: brittle. You're liable to send shards of this thing all over the place.


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[Bobbybob]

You have several you said, why not use two?

 

[drthrob]

You have several you said, why not use two?

Takes up too much space on an 80 mm computer fan.


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[william_shakes_beer]

What happens when ypou place the sir bar directly on the reing magnet? does it lie flat or stand up?

 

[drthrob]

What happens when ypou place the sir bar directly on the reing magnet? does it lie flat or stand up?

it lies flat, but moves off to one side.


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[Bobbybob]

Totally break the magnet then.:cross: