My Stirplate... Cheap and Easy Build...

FredTheNuke said:

www.homebrewstuff.com has stir plates for $42. Based on cost of the parts for the DIY and the value of my time that is a damn good price!!!

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Cost of parts? All mine were free less $2.00 in bolts. and it took maybe 15 minutes to do.

FredTheNuke said:

www.homebrewstuff.com has stir plates for $42. Based on cost of the parts for the DIY and the value of my time that is a damn good price!!!

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So I saved 12 bucks. I killed a 6er of homebrew and spent an evening acting like MacGyver in my workshop (making something out of nothing). And best of all, the damned thing works!!

Now if I can make a fermentor out of chewed bubble gum and duct tape. ... Never mind ...

So I made a stir plate out of a 12v pc fan, hard drive mag and spliced in a power supply. I didn't have a rheostat laying around so rather than spending a few bucks, I used a 5v power supply. Thought being less power, lower speed....

Take a look at the vortex it produces and let me know what you think-

Im no pro but I would say its constantly moving and that's better than the occasional stir a few times a day? This is a 2oz/500ml starter, I think I might not have enough behind it to start a larger batch but I would say this is a good start.

Cheers:

FYI computer repair shops have a TON of old hard drives letting around, I got two hugh earth ags for 3 usd.

Hey all - virgin post here so be nice...

I actually built this before discovering the forums. I haven't read all of the 100+ pages - but a good chunk of them and didn't see anything like my very simple setup. I was at Fry's for a cheap fan and saw an Antec 3-speed 80mm for $6 and thought I'd try it. Speeds are 1500/2000/2500 rpm with a simple switch. The local RS was out of the 25 ohm rheostats so I thought I'd try it without and see what happened... could always add one later. I knew I wanted the magnets (.475" rare earth) away from the fan and the 1" pvc bushing was the perfect height (about 1.25") for my cigar box with a good surface to mount the magnets. Had some strong double sided tape that allowed me to dial in the spacing before epoxying. Found that 1.125" on center was perfect for my 1" stir bar. If I've learned anything from reading this and other forums/YouTube is that bigger bars = more trouble!

Works great! The 1500 is about perfect for 750 ml in a 1L flask with a vortex bouncing all the way to the bottom and even the 2000/2500 speeds won't throw the bar - I can imagine the higher speeds will work well for larger starters/flasks. Power supply is 12v from an old router. Total of about $8 in parts.

So - no rheostat, no on/off switch... center the bar and plug it in... away you go. Worked beautifully on a stepped starter last week...

Built one of these this afternoon. Cost $19. Waiting on stir bar to try it out. Thanks for the how to!

Tested out my new version this week. Building it for a friend. Using a 1.5" stirbar and 4 small round rare earth magnets, and a Homebuilt PWM circuit.

On about as low as I could get it, 1800ml still have a very pronounced vortex. The stirbar rattled badly until I realized the flask was not level to the stirplate. A small shim under one corner fixed that.

There is a small hum from the PWM, but not bad at all. I have it sitting on my desk and I can play games and listen to music without being disturbed. I probably wouldn't prefer to have it next to my bed, but it probably wouldn't keep me from sleeping either.

My thoughts after this experiment is that 1.5" stibar is actually pretty long for a small flask. Where my 3/4" bar does fine, the 1.5" almost seems like overkill. PWM is nice and I like the fine control you get, but my old stirplate work great with just a POT and wall wort.

The magnet alignment seems better on my new version. The bar is held tight throughout the full speed range. I haven't tried it with my 3/4" bar yet, but I expect similar performance.

Next step for testing is putting the 1 gallon jug up there and see how it goes.

I use a 1 inch bar with a 1 liter and it seems to be just about right, so not to make a cake and keep everything moving, but that is at about 1/3 power.

Just got mine done last night. A big thanks to everyone who contributed to the thread with advice, pictures and most importantly DIAGRAMS of the wiring.... that was most helpful


Here I've got shots of a 1.5" stir bar in a quart size canning jar on the lowest setting... WAY overkill as it looks like the Tazmanian Devil spun up a tornado in there (is there such a thing as too much spin?).

I have a 1" stir bar on order so hopefully it will be a little more tame.








I put a hole in the back of the box and the side of the box as well to allow for good circulation of air. Don't know if that was needed but it just seemed logical to me to create good air flow around the fan.

GulfCoastGirl said:

Just got mine done last night. A big thanks to everyone who contributed to the thread with advice, pictures and most importantly DIAGRAMS of the wiring.... that was most helpful

Here I've got shots of a 1.5" stir bar in a quart size canning jar on the lowest setting... WAY overkill as it looks like the Tazmanian Devil spun up a tornado in there (is there such a thing as too much spin?).

I have a 1" stir bar on order so hopefully it will be a little more tame.

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You need nothing more than a 1" to 2 " vortex / dimple. The one inch stir bar will help but also get a lager container like a 2000 ml lab flask. The lab flask works well with the stir bar since it has a very flat bottom. Can you slow it any without stalling?

Mellow52 said:

You need nothing more than a 1" to 2 " vortex / dimple. The one inch stir bar will help but also get a lager container like a 2000 ml lab flask. The lab flask works well with the stir bar since it has a very flat bottom. Can you slow it any without stalling?

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I got my 2000 ml Erlenmeyer flask today and got it to spin once but then I turned it off and when I turned it back on it kept throwing the bar. I got irritated and gave up but I'm guessing it has to do with that big stir bar (which is the hexagon type). The new one I have on order is smaller and round so I'm thinking it will do better in the flask.

As for speed... that picture is the lowest setting. Unfortunately I didn't heed the advice of others here who said 12 v might be too much. The fan is 12 v and I let the guy at radio shack talk me into the 12 v DC power pack, he said the fan wouldn't run on anything lower. I'm a dummy... next time I'll know better

Is there a problem if the vortex is too strong?

GulfCoastGirl said:

I got my 2000 ml Erlenmeyer flask today and got it to spin once but then I turned it off and when I turned it back on it kept throwing the bar. I got irritated and gave up but I'm guessing it has to do with that big stir bar (which is the hexagon type). The new one I have on order is smaller and round so I'm thinking it will do better in the flask.

As for speed... that picture is the lowest setting. Unfortunately I didn't heed the advice of others here who said 12 v might be too much. The fan is 12 v and I let the guy at radio shack talk me into the 12 v DC power pack, he said the fan wouldn't run on anything lower. I'm a dummy... next time I'll know better

Is there a problem if the vortex is too strong?

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I don't think that it is a real problem creating such a violent stir but as you already know it will frustrate you throwing the bar.

The 12v adapter was not a mistake. It sounds like you have the electronics wrong. My stir plate will go from a crawl to way too much and that is the trick to not throwing the stir bar, you have to ramp it up slowly and get the wort moving first.

I will be glad to share the exact part list and wiring diagram if you want. I got it all from my local Radio Shack. It will give you full speed control without throwing the bar and slow things down.

GulfCoastGirl said:

...

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GulfCoastGirl said:

I got my 2000 ml Erlenmeyer flask today and got it to spin once but then I turned it off and when I turned it back on it kept throwing the bar. ...
Is there a problem if the vortex is too strong?

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Are those magnets glued down? I know I originally thought mine would hold itself to the washer by magnetic force alone, but after awhile the magnet started drifting. If your fan isn't slowing down much an additional resistor or lower voltage is in order.

In theory there is a point above which shearing force could cause damage to the yeast ... but your not anywhere close to that.

Edit: you are also the first I've seen to use ring magnets.

Randomly decided to build one today. Primitive looking wiring. Was fun.











Want to try 6 volt power as i think low is to violent.

Smurf here is a pic of my 6v system I was worried it was too tame but after some reading I think it will do...even though I would like the cone to touch the bottom.

Mellow52 said:

It sounds like you have the electronics wrong.

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I'm fairly positive the electronics are fine. I have the same parts as the OP and my wiring is the same way. I had it wired a different way at first and it didn't work. I re-examined the posts here, found my problem, changed the wiring and it works now.

FWIW, the rheostat does control the speed of the fan. When I turn the dial it speeds up to full force. It's just that even on the lowest setting it's nowhere near "a crawl".

I did look up some fans that others here have used and I'm seeing that many of them have much lower RPMs than mine so it makes sense that those might spin much slower than mine at the low setting.

It's no big deal.... I got the bar to spin this morning in the flask and let it run for 1 1/2 hours while I worked out and it did fine... didn't throw the bar. I really hate the hexagon shape of this particular bar and I think I'll have more success with the smaller, flat, round bar that I've ordered.

camiller said:

Are those magnets glued down? I know I originally thought mine would hold itself to the washer by magnetic force alone, but after awhile the magnet started drifting. If your fan isn't slowing down much an additional resistor or lower voltage is in order.

In theory there is a point above which shearing force could cause damage to the yeast ... but your not anywhere close to that.

Edit: you are also the first I've seen to use ring magnets.

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Thanks for the post! No, the magnets are not glued down. Those are "super magnets" I picked up at Home Depot and it was VERY difficult for me to pry them apart so I figured they would hold just fine but I'll open it up and see if they've moved at all. Honestly the thing works just fine on the smaller jar it's the flask that I'm having hit or miss success with and I really do think (from all the reading I've done) that the smaller, flat round bar will make a difference. If it doesn't, I'll rip out that 12 v power and put a 9 v on it. I'm not gonna let a little stir plate kick my a**


Here's a picture of it spinning in the flask. I also discovered that if I got the magnet centered.... then lifted the flask just a little while starting the fan until the vortex got going and then set it down I had better chance of it not throwing the bar. This makes me think maybe I should lower the fan inside by 1/8".

GulfCoastGirl what size of bar are you using, mine is posted around the 101 thread count and looks just like yours, but I lowered mine a little bit?

Gear101 said:

GulfCoastGirl what size of bar are you using, mine is posted around the 101 thread count and looks just like yours, but I lowered mine a little bit?

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The bar I currently have is a 1 1/2" hexagon shaped bar. from reading here I see that most people get the 1" bar and have no issues so I ordered a couple in 1" and also not hexagon shaped.

If the new bar doesn't solve the problem, I'll drop the fan down a little bit and change the power supply as a last resort. No big deal really as it does work now.... it just takes me a minute to get it going. I'm going to use it this weekend as-is

This is a fool proof wiring diagram. All parts is obtainable from your local Radio Shack.



This will allow for perfect speed control. Using just a potentiometer will work at first but wont last and last. You wont get good speed control and using lower volt DC adapters for speed control is silly. Don't do it, build it right.

Also checkout this handy link: http://www.stirstarters.com/instructions.html

If you like DIY then build one if not just order one from here, it is much easier and only marginally more expensive than parting and building it yourself.

Cheers to happy yeasty beasties!

GulfCoastGirl said:

not hexagon shaped

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You will find the shape has no real change in effect, only length will. Also see if you can get the solid round shaped rare earth magnets at Home Depot (about $3.60 for a pack of 6) I am not sure those 'washer' magnets are doing you any favors and be sure to glue them down or they will shift. Don't lower the fan/magnets you want them as close as possible for a good 'coupling' with your stir bar. Rather fix the electronics for proper speed control.

Good luck in fine tuning your machine!

GulfCoastGirl said:

...I also discovered that if I got the magnet centered.... then lifted the flask just a little while starting the fan until the vortex got going and then set it down I had better chance of it not throwing the bar. This makes me think maybe I should lower the fan inside by 1/8".

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What I did was to cut a piece of rubber mat used in kitchen drawers and shelves to keep things from sliding around. You can find it at almost any big store or grocery store.

Cut a piece to cover the top of the stirplate and cut a hole in the middle for the magnets to spin within. Keeps the flask in place and lifts it up a bit to clear the magnets.

I need mine to be a bit high for when I put the 1 gallon tea jug on it for lagers and big beers.

Mellow52 said:

Also see if you can get the solid round shaped rare earth magnets at Home Depot (about $3.60 for a pack of 6) I am not sure those 'washer' magnets are doing you any favors and be sure to glue them down or they will shift.

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I'll see if I can find those magnets, thanks for the help

Homercidal said:

What I did was to cut a piece of rubber mat used in kitchen drawers and shelves to keep things from sliding around. You can find it at almost any big store or grocery store.

Cut a piece to cover the top of the stirplate and cut a hole in the middle for the magnets to spin within. Keeps the flask in place and lifts it up a bit to clear the magnets.

I need mine to be a bit high for when I put the 1 gallon tea jug on it for lagers and big beers.

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Ahhh... great idea! I've got rolls of that stuff left over from when I lined my kitchen shelves & drawers. Thanks

OK. Problems. Stir plate is assembled and the stir bar arrived. Unfortunately it just sits in the center of the beaker and rattles. I moved the magnet and it stirred briefly and then stopped. Can't get it going. Help please.

befus said:

OK. Problems. Stir plate is assembled and the stir bar arrived. Unfortunately it just sits in the center of the beaker and rattles. I moved the magnet and it stirred briefly and then stopped. Can't get it going. Help please.

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Why the stir bar did not spin:
What is the distance between the magnets and the stir bar? What magnets are you using, rare earth? Is your magnets glued down? If you are using two magnets do you have the same poles facing up (++ or --) or alternate poles facing up (+-)? Can you upload pictures?

Why the fan now does not spin:
If the fan is not turning when you turn the pot bypass everything and go straight from the DC adapter to the fan to locate the problem. If the fan still turns then it is the pot, if the fan does not spin up well then it puked assuming the DC adapter is still fine.

Sorry for all the questions.

Mellow52 said:

Why the stir bar did not spin:
What is the distance between the magnets and the stir bar? What magnets are you using, rare earth? Is your magnets glued down? If you are using two magnets do you have the same poles facing up (++ or --) or alternate poles facing up (+-)? Can you upload pictures?

Why the fan now does not spin:
Sorry for all the questions.

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Fan runs fine. I am using one magnet from a laptop hard drive. It is probably a quarter of an inch from the top of the project box. It is not glued down as I want to be able to adjust it. Good thing I guess as it sure isn't working as it is. The stir bar is an inch and a half long. The wierd thing to me is that it worked twice and either threw the stib bar off to the side or just quit spinning? That's all I got.

befus said:

Fan runs fine. I am using one magnet from a laptop hard drive. It is probably a quarter of an inch from the top of the project box. It is not glued down as I want to be able to adjust it. Good thing I guess as it sure isn't working as it is. The stir bar is an inch and a half long. The wierd thing to me is that it worked twice and either threw the stib bar off to the side or just quit spinning? That's all I got.

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OK does your pot control the speed well meaning can you make it spin real slow? Does the magnet and the stir bar couple well?

The way stir plates work is ramping the speed till you get the vortex desired. If you start at high speed the bar will get tossed. I am thinking three things are happening here. The magnet is moving since it is not glued down and your stir bar is way way too big and your fan speed is too high. Get a stir bar no more than 1". I would spend the $3 and get the round disc rare earth magnets from Home Depot and mount two of them, glue'em. Make sure you have full speed control and keep the magnet and stir bar as close as possible for good coupling, 1/4" is too much so get them closer. Look at my post on the previous page if you need help with a good speed control system.

Thank You Mr. Lopez,

You're info was right on! I substituted a free Cigar Box I picked up @ Bevmo when I was buying Ovila Dubbel.

An update to your original post dated 2008, today's cost is a whopping $15, but Radio Shack's part numbers are still the same.

The most expensive item was the additional $5 stir bar from EBay.

I am completely inept when it comes to electricity & your explanation was right on!

My 1 question is: How long to I rest the yeast starter on the stir plate......... 1 day or 2 days?

Slyko said:

My 1 question is: How long to I rest the yeast starter on the stir plate......... 1 day or 2 days?

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If I have enough time, I'll do 24 hours. If I don't, I'll let it go for 18. I've heard anywhere from 18-36 is typical for maximizing the effectiveness of the starter, though I welcome any correction by people who've read the Yeast book (don't have it yet).

So I brewed a Hefeweizen last weekend and I made a starter on my new homemade stir plate. Here it is at about 28 hours.

The stir plate worked without any problems and I actually liked the larger stir bar.... did a great job in the starter, which is thicker than water, and never got thrown once.

Thanks again for the help.... this is a great thread!

Diaperload,

You weren't by chance a recruiter in a past life were you? That first stirplate looks surprisingly similar to the old "200 card" boxes. I used to recruit in Salem, Or.

I built this plate almost exactly as you all did. I used the magnets that you recommended from kj magnetics. However, i can't get it to stir my 2inch bar. When the magnet lines up with the bar and you turn it on, the fan doesn't even spin. Do I need to increase the distance or up the power supply? I'm running a 6v currently. Also could it be the size of the bar?

Any help would be great.

Thanks

BraxtonBrewery said:

I built this plate almost exactly as you all did. I used the magnets that you recommended from kj magnetics. However, i can't get it to stir my 2inch bar. When the magnet lines up with the bar and you turn it on, the fan doesn't even spin. Do I need to increase the distance or up the power supply? I'm running a 6v currently. Also could it be the size of the bar?

Any help would be great.

Thanks

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On mine the magnetic power was too much. Increased the distance between magnets and voila . Raise your flask above the stir plate and hold steady. If it spins good then you'd need to calculate that distance for how much to go (what I ran into on mine). On my stir plate, I glued a piece of PVC to the fan. Then I glued a metal washer same diameter of PVC on top of the PVC. Then glued the hard drive magnet to that.

also, a 2" bar is rather long and gets thrown easily - consider a 1" or even 3/4"

Took me forever to get mine gowing. It just kept throwing the stirbar no matter how low I turned it down. I read this thread last night and changed from a 12 to a 9 volt transformer and it is working perfect. Thanks guys

Whatever makes it work but controlling the speed by exchanging wall warts is not the way to do it. Build a correct speed controller and you can make the stir bar do a pirouette on command. Just saying.

Finally got around to building mine tonight out of an old power supply, about 10 bucks out of pocket at radio shack plus the stir bar I'll need to buy. Good use of a Monday night.

Finally finished the circuit to my stir plate last night. Either have to get more drive magnets or purchase some stronger ones because it was tossing my 1" bar on about 3 volts. Just have to put a washer and glue them down to see if that helps or put two to four on each side of the washer. Anyone have luck with the hard drive magnets on a 120mm fan or just purchase stronger ones?

in the photo, the magnet doesn't look centered - that will be your #1 issue. if you can use two magnets across from each other, make sure they're oriented so that the stir bar "sees" north on one, and south on the other.

Yeah I threw it on the fan just so I wouldn't lose them in my room AGAIN (lost them like 4 times during multiple runs to radio shack and drinking)! The fan itself pushes them in that order but if I separate them they align perfectly on the outside but lose their strength. So I need to open up a few more hard drives here at work to stack them. Was just wondering if the hard drive magnets would be enough on the 120mm fan or should I just purchase some stronger ones?

rpryor said:

Yeah I threw it on the fan just so I wouldn't lose them in my room AGAIN (lost them like 4 times during multiple runs to radio shack and drinking)! The fan itself pushes them in that order but if I separate them they align perfectly on the outside but lose their strength. So I need to open up a few more hard drives here at work to stack them. Was just wondering if the hard drive magnets would be enough on the 120mm fan or should I just purchase some stronger ones?

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The diameter of the fan shouldn't matter, and it is hard for me to see whats going on with your picture because the center is all washed out from reflection of the flash or other lighting. Because of the nature of hard drive magnets I don't think stacking them is going to help. When you stack disc magnets the faces are the poles (usually) but with hard drive magnets the ends are the opposite poles.