DIY Stirplate

[Sly13rewer]

I was wondering if anyone knows what might be wrong with my set up. I've been using a 12V power supply into a 12V DC fan with 2 rare earth metal magnets. It runs fine for a little while but when I turn my back, the fan has stopped working. The last time this happened, I replaced the power source with 10.5V and it worked just fine. I decided to replace the power source one more time with a 12V and now neither power sources will work.

Any advice?

 

[BrewingReverend]

Sounds to me like your fan took a dive. When you rebuild it try to space the magnets farther from the fan with a piece of PVC. Also build it with a stronger fan should help carry the extra mass.

 

[Sly13rewer]

Thanks for the advice, I'll give this a try.

 

[william_shakes_beer]

Yeah, the magnets interfere with the magnetic feild that runs the fan. I used a 1/2" wood spacer that I cut with a hole saw and gorilla glued to the fan hub. I can turn the fan at proper speed with 3V of power. I use an adjustable wall wart as a speed controller.

 

[Monster Mash]

Yeah, the magnets interfere with the magnetic feild that runs the fan. I used a 1/2" wood spacer that I cut with a hole saw and gorilla glued to the fan hub. I can turn the fan at proper speed with 3V of power. I use an adjustable wall wart as a speed controller.

This is the best thing to do. If you space the magnets away from the fan you don't need a 12v power supply, in fact in won't work because it's too much power.

I use a 6v on mine and it works great.

 

[Hang Glider]

also, some fans don't work at all if they're wired backward - they don't spin backwards, they just don't spin. Try reversing the wires. (i also approve the spacer - mine are spaced above the fan so there is less magnetic interference with the armature.)

 

[CapnBry]

I just built my stirplate yesterday and something else I found was if the magnetic force was too much, it would basically pin the stir bar to the lid of the box and the friction would prevent it from moving at all. I actually removed some magnets and it works great despite having less force. This assumes your fan spins fine without the stir bar in place though.

 

[jtkratzer]

I built one with a pc fan about a year ago and it worked very well with a 2L flask and a 1.25" stir bar. Picked up a 5L flask and the small stir bar isn't cutting it and it keeps throwing the 2" bar. I tore the thing apart to spread the magnets out to better suit the larger stir bar.

This is the stir bar:
http://www.amazon.com/gp/product/B002VBW5G8/?tag=skimlinks_replacement-20

I can't get the fan speed going high enough before the bar gets thrown to get much of vortex going. Didn't think the vortex needs to be huge to keep the yeast in suspension and exchange the gases.

Please confirm that all you basically need to do is agitate the liquid to be effective.

 

[william_shakes_beer]

You don't NEED a vortex at all, although Tim Taylor would be suitably impressed. You just need to keep the liquid moving, which keeps the yeast in suspension and provides even contact time with all yeast cells to the top of the wort where the oxygen hangs out.

 

[jtkratzer]

You don't NEED a vortex at all, although Tim Taylor would be suitably impressed. You just need to keep the liquid moving, which keeps the yeast in suspension and provides even contact time with all yeast cells to the top of the wort where the oxygen hangs out.

That's what I thought, just an agitation.