capcrnch

Recipes 

Radio Shack also sells a voltage adjustable plug. I believe it goes from 6v to 12v.
Easy way to adjust your speed too.

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WBC

Recipes 

I found the problem with the fan interacting with the magnet in the fan itself and solved the problem (The fan would not spin at full speed with the magnet mounted directly on the fan). I used a non-magnetic spacer between the fan and the magnet made from wood. I glued the wood to the fan (round 1.0 inch long) centered and then found the best mounting point (trial and error) on the wood and then permanently glued it in place. Final balancing can be done with adding a small metal nut(s) at the exact point the extra weight is needed. My fan now spins at full speed with no vibrations at all. The full magnatism is now focused on the spinning bar and it works fantastic on a 2 liter flask. I can make the vortex extend completely to the bottom of the flask.

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Cheers,
WBC

Fermentor 1: Bill's House Ale II, Fermentor 2: German Helles, Fermentor 3: Bill's Schworzbier (Black Bier)
Tap 1: Bill's House Ale II, Tap 2: German Hefewizen, Tap 3: Nut Brown Ale
Future Brews: Stone IPA Clone, Blonde Ale, Budvar Clone, Newcastle Clone
New toy: Blichmann 27 gallon fermentor

“If you find yourself in a hole, the first thing to do is stop digging”

“Good judgment comes from experience, and a lotta that comes from bad judgment”

Pelikan

Recipes 

Got her figured out. When I took apart the hard-drive for the magnets, there were two. I glued only one to the fan. In a last-ditch effort, I put both magnets on the fan. Now I have the 12 volt adapter on it running full tilt and it's not kicking the stir bar (w00t!). The vortex is all the way to the bottom and sending a crazy amount of bubbles through the water.

I'm a little salty about burning $15 on the 6 volt adapter that is now useless, but $30 overall for a stir plate is still about $50 in the pocket for me.

I guess my final question would be: can these things run too fast? As in, so fast the stir bar would beat up the yeasties?

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On a brewing hiatus. Will get back into the fray eventually, methinks...

Anthony_Lopez

Recipes 

one thick hard drive magnet centered on my fan washer worked great for me... from what I understand, keeping the starter moving is the most important part...

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I'd rather have a bottle in front of me, than a frontal lobotomy.
--Tom Waits

You can't be a real country unless you have a beer and an airline - it helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer.
--Frank Zappa

My Cheap and Easy Stirplate

WBC

Recipes 

Yes there are 2 in each hard drive and you only use 1 of them. When the magnet is mounted on the fan if it feels like the magnetic poles are interacting with the magnets on the fan then the only way to use that fan is to put a spacer in between the fan and magnet to reduce this effect.

You will find it takes less voltage to do the same thing if a spacer is used. See above paragraph.

Maybe not, you will find a use for it.

Yes, the stir bar will get thrown off to the side a lot.

Not really, they are tough little guys.

__________________
Cheers,
WBC

Fermentor 1: Bill's House Ale II, Fermentor 2: German Helles, Fermentor 3: Bill's Schworzbier (Black Bier)
Tap 1: Bill's House Ale II, Tap 2: German Hefewizen, Tap 3: Nut Brown Ale
Future Brews: Stone IPA Clone, Blonde Ale, Budvar Clone, Newcastle Clone
New toy: Blichmann 27 gallon fermentor

“If you find yourself in a hole, the first thing to do is stop digging”

“Good judgment comes from experience, and a lotta that comes from bad judgment”

Pelikan

Recipes 

The fan I'm using works fine without magnetic insulation. 6 volts and one magnet = Very small, 1" vortex. 9 volts and one magnet = stir bar getting thrown. 12 volts and two magnets = super-vortex right to the bottom of the flask.

In my case, it was a lack of power on two fronts: electric power to the fan and the magnetic power to hold the stir bar. Thankfully I got them both solved.

__________________
On a brewing hiatus. Will get back into the fray eventually, methinks...

tedski

Recipes 

I used some nice small magnets from McMaster Carr. Part # 5862K63

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"This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our maker and glory to his bounty by learning about... BEER." - Friar Tuck

mthompson

Recipes 

I never got mine to work right with the HD magnets I have (tried all combinations of 4 different magnets). I found some magnets at Hobby Lobby that are rated 10 on the 1-10 strength scale - although not as strong as the hard drive magnets. I bought the 1/2" (or so) ones, that came 3 to a pack. Put them on a metal washer tha't glues to the fan, two per side with opposite poles up. Easy to center this way, and spins the the stir bar pretty good.

I am gonna try a few different fans now to get one that spins faster, because I thing the hard drive magnets without the metal washer messed up the fan somehow.

The current set-up works, made a 900mL starter for my pale last weekend that got really thick with yeast. But, the vortex only goes down about 3" - I'd like at least 4" plus more speed if I need it.

Later,

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MT
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Save me, O God! For the waters have come up to my neck. - Psalm 69:1

Pelikan

Recipes 

Try the drive magnets again. The key with me was using 2 HD magnets and a 12 volt power supply. It needs enough magnetic power to hold the bar in place, coupled with enough electronic power in the fan to generate torque. Your fan might be the culprit as well. I had to go through three of them before I found one that could meet the needs of this application (ended up using an Intel CPU cooling fan I had around). They need to have a fairly torquey motor.

Another thing to consider is make sure you're using the properly sized stir bar for the application. Even though this thing tears-A with the "micro" bar, it will throw the larger bars because they're not suited to the size of the HD magnets I'm using.

This thing seriously rocks now.

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On a brewing hiatus. Will get back into the fray eventually, methinks...

Yunus

Recipes 

I'm building one of these and something I discovered is that many of those old transformers (cell phone plugs or whatever your using) are not the voltage they claim they output. I've found them above and below ratings. The first one I tried claimed 10V but my multimeter said 15.4. I'm afraid I'll burn a fan with that.