Saturday, July 12, 2008

Boredom strikes!

And when it strikes, it strikes hard, at the very heart of science! BWAHAHAHAHA

Ok, not really. But I did finally figure something out for an eddy current heater thingamabobber I've had on my mind.

I took something from a previous boredom session, a wooden disk with a spindle, and I centered and drilled four holes in one of the hard drive platters. That, and a clamp for the magnet, and I had my demonstrator.

And, with the drill press on it's highest speed setting, gets too hot to touch. Myth confirmed. Wait, wrong show...

1 - I'm not sure what the drive platter is made of, and it may not be as conductive as an aluminum or copper disk.
2 - The magnets could be closer together, and since magnetic fields run on the inverse square of distance, that will increase the eddy and the heating.
3 - I'm limited here by speed, but a bigger disk would have higher rotational speed at the edge. With the original wind powered idea, I'll either need a big disk or a gearbox, with the latter being more likely.
4 - There are stronger magnets out there, and multipolar setups work much, much better than what I have.

Still, too much stronger and I'll either overstress the drill press, or actually heat the disk to a failure point... which I really kinda wanted to see... at least a dull red. I figure I got around 250-300 degrees F running, but it falls off fast because of surface area and heat conductivity when it's stopped.

The "end game" of this idea was a little wind-powered unit for arctic climes... basically, cheap free heat with no maintenance. If you make heat with friction, you eventually wear it out; make heat with electrical generation and resistance, and you drive the unit price up. Make heat with a cheap aluminum disk in an oil bath running between a series of rare earth magnets, and you've got something simple, inexpensive, and it'll run forever.

I mean, it's not like there's a shortage of wind above the arctic circle...


Blogger Joat said...

Cool, same effect as a strong magnet dropped into a copper pipe. If you put it in an oil bath you will get some friction heating.

3:46 PM  
Blogger phlegmfatale said...

wow, the second and third photos are really cool!

10:03 PM  
Blogger Roberta X said...

What's the Curie Point of the rare-eath magents?

10:31 AM  
Blogger Dr. StrangeGun said...

Ooof, good point. The magnets I'd intended poop out at 176F.

10:54 AM  
Anonymous Ritchie said...

And if you put electrical brush contacts near the center and edge of the platter under the magnet, you should get electricity out. Voila, electricity turned into...ELECTRICITY! The platter is almost certainly aluminum. In the olden days they were optically flat glass disks. Now, if you really want to clear out a machine shop, make a drill press mounted centrifuge!

8:33 PM  

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