My shamelessly cheap $12 DIY stir plate

yep. 1"

BTW, I meant to say 2000ml above.

 

Is there a good rule of thumb for inches per mL when it comes to stirbars?

 

Subscribed

Cheers

 

just finished my DIY stir plate... Cost $0.00..

Pulled a fan off an old junk computer.
Pulled the magnets out of an old 80gig HD
Cut a power supply from an old cable router that I can't use

Just put the wires together with electricians tape, and hot glued one of the magnets to the middle of the fan. Spins fine when I plugged it in, so I set the fan into a chunk of styro foam that I cut out. When I sit my 2L flask on it with a stir bar, It is nice and "cushy".

I plugged it in, and it worked right off the get go, pulling in a 4"-6" vortex with a 1 1/4" stir bar after about 10 seconds. I suppose this is a bit overkill, but I haven't seen anyone say that a vortex will hurt the yeast.

Easy! Thanks for the idea.

 

Got mine up and running. Well less than $20. Can't beat it. Got a starter going this morning, and its humming along. Awesome.

I use a 1" stir bar and it seems to work perfectly. 1 or 2 liter (quart) starter. I keep the fan close to the lowest possible speed or it gets thrown.

 

Here is my stirplate I made using a watch box that I never used.
Spinning a 5L starter with a 2 inch bar also it works with a 2L starter.
At higher than half speed it will throw the bar on the 5L.

 

Nifty! Where did you get a box like that?

 

It was a gift from work.

 

Nabbed your idea. Built a prototype in a cardboard Bijoux Terner tie box. Jutting off the lid left the metal/cardboard joint behind so I could wedge the controller into it. Cut a hole out through the side to run the cables out and another for air circulation. Once the magnet is in I'll cover the top with foil to protect it.

I don't think I can overstate how nifty this extension cord is! It goes out quite far and it's probably thin enough to close in a minifridge door.







Gonna need a magnet though. And a stirbar. And a flask.

I'll be looking for less flammable boxes while I get those things. Has anyone heard of stirplates or these USB fans catching on fire from prolonged use?

 

This is my wife's concern as well.

 

If they're brushless DC motors, then that might help prevent flames (compared to brushes). Plus these things are - in general - made to run on PCs and I haven't heard of a PC fire starting with the fan.

But if you're putting a load (a pipe and magnet setup), that might create some kind of drag or wear on the motor. The other issue is if the flask/jar/growler leaks into the housing or if condensation builds up within the box and causes some kind of short.

Yet these are advertised in some cases for drying the insides of boots and have been used in fermentation chambers to push air around. Those could be considered moderately unideal and I don't think I've seen a thread around here about one catching fire.

Been around fancy industrial stirplates for a while and never heard of one catching fire either and those are built with heaters that get up to 300C in some cases. More common, something catches fire on top of them.

 

The first stirplate I made used a very sturdy cardboard box. As I was inexperienced with stirplates, I made the mistake of filling my 2000mL flask with 2000mL of wort, and THEN adding the yeast. Not usually a problem, the constant spinning typically cuts down on krausen, but this was my first attempt, and my stirbar got thrown while I was at work. I came back home to a flask that had a LOT of krausen overflowing the flask getting all over my cardboard box. The fan I used was dry still, but the box no longer was adequate to hold that starter.

Just keep this in mind when making a plate with a material that won't hold its shape if wet. FYI, had I used a foam reducer (such as Fermcap-S) as I do now, I probably wouldn't have had an issue.

 

ok so i think i did everything right but i cant seem to get my stirbar to spin... it kind of nervously hops around the bottom of my flask..

 

I gotta rebuild my stirplate cuz it keeps throwing stirbars. Looks like I found my next fan.

 

Put the bar in the flask with water, and have the magnet grab hold of the bar BEFORE you start the stir plate. Start up the plate from the slowest setting up to wherever you want it, and it should work.

I had the same issue when I tried to place the flask down onto an already spinning stir plate.

 

Deleted, wrong thread.

 

Try flipping one of the magnets over, see if that helps.

 

My [double] take on this build!

 

I finally made mine after having it sit for 2 months. It works on a medium setting, but when it is low it throws the stir bar. I get a vortex going and it seems to work fine at that point. At a high setting it throws the magnets, so maybe I'll glue them on. I just have the basic fan at this point, I'll have to build some kind of enclosure or at least a plexiglas top that's bigger than the bottom of the flask.

So how fast does this need to go anyway? I would think just enough to keep things moving

 

low speed is fine. It's really just to keep the yeast in suspension. Does your stir-bar have a fulcrum on it? I shaved the fulcrum off and it's working better. Prior to that sometimes I'd use cornie dip-tube o-rings on the outer edges of the stir-bar and it would run better at certain speeds. Play around with that and also the height the fan is from the flask. I also have to do different things for different vessels (I have a 2.36L pickle jar I use for larger starters and the bottom is concave, etc.)

 

Just ordered the 12.

Also, I thought the purpose was not to keep the yeast in suspension, but rather to oxygenate the wort?

 

It's both. Trying to keep them in a perpetual state of reproducing, sort of...obviously they won't keep producing forever.

 

What do think about this for a cheap easy stir plate?

 

Looks good. What store is that at? Also, is that "tornado" chamber permanently affixed to the stirplate bottom? Or can you remove it and put an erlenmeyer flask on that bad boy? I would check first. You don't want to be stuck making starters in that cheap plastic kids tornado tube.

 

Last fall I saw this thread and instantly decided it was time to put a stir plate together, finally.

I used the same fan, and took advantage of scrap pine and some plywood, a few nails, screws, a HD magnet, hot glue, an HTC phone charger, and voila, lookee here.

 

I love how Amazon suggests a stir bar in the 'Frequently Bought Together' section. Must be a popular build.

 

Haha yeah, guarantee you there's been tons of people seeing this thread and others on Reddit, and immediately looking for both items on Amazon.

I got my fan off eBay, as it was 12.99 w/free shipping.

 

I know I bought them together. Should have gotten the magnets at the same time. As it was I think I spent $10 at the HW store...

 

Looks almost identical to mine

 

I used the computer fan, a cigar box, and magnets from an old hard drive. I like the variable speed control (in the upper right of the closed box).

 

So is the flask necessary/worth $15 for a 1L? Or can I use a mason jar?

 

It depends. If you can get your stir bar to balance and not get thrown off of the center, then you don't need it. I personally think it's worth it. Also, spring for the 2 liter if you do, less steps if you ever need to make a lager.

 

Thanks, so assuming the same fan this thread identifies and a 2L flask how big of a stir bar?

 

I use a 1 inch stir bar with good results.

 

1 gallon growler $5
USB Fan $19 ( i got the 12 )
$4 stir bar
salvaged hard drive magnet

For under $30, you can get a stirplate that can make 3L starters.. awesome find!

 

They do make stir Bars for convex bottoms. Look up barbell stir bar, they aren't as cheap but they aren't horrible if you are doing a large starter and don't have a 5L+ flask. Brewmasters Warehouse did have them, they might get them in sometime soon.

 

Sorry if I repeat a question but why does my stir bar keep getting tossed off center? At lower speeds I can get it to stay but with no whirlpool action. I can see at low speeds its spinning just a little off center almost doing tiny circles while also spinning. My assumption it the the magnet is a hair off center but its a HD magnet so it's a funky shape. Any ideas?
(2L flask, 2 laptop hard drive magnets stacked, 1"stir bar, thread specified fan)

 

One thing that helps is having a bigger stirbar. The 1" won't cut it to make a full 2L flask even show a ripple, much less a full vortex. Another thing to check out are stirbars with the ridge in the center that acts as a fulcrum for it to spin on. And lastly, when dealing with funky shaped HD magnets (I have them and so do many many many of the other homebrewers out there) what I found worked super well was to literally just sit there with your stirplate cover off and spin your fan and adjust the magnets over and over until you find a sweetspot where you see very little wiggle or wobble. Then rather than drawing an outline and then applying glue to the back side and possibly losing the exact position, just mix up a mini batch of JB Weld and goop it all around the magnet edges to lock them in place at that aforementioned sweetspot.

 

How do you do that? If I am just using the magnet and fan I can't identify the center point because of the shape. I tried with the stir bar on the magnet but there is a little play in where the stir bar will stick so that doesn't seem reliable enough.

 

i'm using a 1" stirbar with the hard drive magnet, the model 12 fan an am able to get a "slight" vortex in a 1 gallon growler.. minimum of 1" in the starter.. 3-4" in water. It did take a little positioning of the magnets to optimize it.