My take on the magnetic stir plate

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John Beere

Deep Six Brewing Co.
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Inspired by MrSaLTy's post @ https://www.homebrewtalk.com/showthread.php?t=8850&highlight=stir+plate

So I went the cheap (and easy) route and made myself a stir plate. The only thing I had to buy was a new beaker ($12), a magnetic stir rod ($3), and some magnets as I did not have much luck with the magnets I removed from a few old hard drives. I bought the magnets on eBay for $10 for 10 + $5 shipping. They are 1/2 x 1/4 Neodymium discs with an N48 rating (read: crazy strong). I only needed 2 magnets but I couldn't find anyone selling them in less quantities.

I found an old 120 MM 12v computer fan and an old switchable voltage AC Adapter. I sacrificed the AC Adapter and hard wired it directly to the fan. After some experimentation it turns out that about 6v is about perfect. After the starter thickens up, I can crack it up to 7.75v without throwing the rod. I experimented with the magnet placement and side-by-side, like show below, worked best. I robbed the glass out of one of my wife's small picture frames and placed it on top with some spacers.

stirplate1.jpg



Here is the starter right when I turned it on around Midnight
stirplate2.jpg


Here it is the next morning
stirplate3.jpg


And here it is when I called it "finished"
stirplate4.jpg
 
Cool.... fun huh? :D The only other thing I'll say is that if you get really strong fermentation you may get yeast overflowing that can spill over and into the fan. I'm just saying that maybe some day you may want to protect it some more. I don't mean that as a knock.... just as a precaution. Hey, that may never happen. Works great and thats all that matters.
 
What's that you have on the top of your beaker plug? An inline filter of some sort? Where, pray tell, did you get that?

Looks good. I spent like $50 putting together the one MrSalty outlined on here. Lol... had a electrical engineer friend of mine take a look at it. He laughed at my horrendous solder blobs and scoffed about some EM interference or some such. But it works! So I'm happy. I probably saved $50 off a new stir plate.

I have to say... the one John Beere has made is definately a good deal. Wish I'd had the same take on the idea...
 
MrSaLTy said:
Cool.... fun huh? :D The only other thing I'll say is that if you get really strong fermentation you may get yeast overflowing that can spill over and into the fan. I'm just saying that maybe some day you may want to protect it some more. I don't mean that as a knock.... just as a precaution. Hey, that may never happen. Works great and thats all that matters.

Thanks much... I honestly didn't even know if it was going to work and just slapped this together as a trial... worked so well this will probably be the finished product - although I might just get a larger piece of glass that fully covers the fan and give the Mrs her picture frame back... heh
 
Your magnets seem like they are pretty close to each other. You will get better control with the magnets spaced off of the fan, they interfere with the fan motor and make it difficult to get going and adjust the speed. I use a block of wood or a popcicle stick.

If you make an aluminum foil tray it will prevent any spillage from getting in the stirplate.

Stirplates1.jpg
 
Monster Mash said:
Your magnets seem like they are pretty close to each other. You will get better control with the magnets spaced off of the fan, they interfere with the fan motor and make it difficult to get going and adjust the speed. I use a block of wood or a popcicle stick.

I did notice some light interference with the motor and may try placing something between the fan and the magnets like you suggest. Thanks
 
When you glue the magnets to the spacer attach them to your stirbar first and then glue them down. This will get the spacing and polarity dead on. I leave the stirbar attached until the glue dries, this keeps them from being drawn to each other.
 
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