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

jafo28 said:

Finally got mine working. I had to put a resistor on it because my 12 volt power supply was throwing the bar. I still can't turn it up all the way, but I think i'm getting enough of a stir going on. I'll post a couple of pics to see what you guys think.

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You might try another magnet on there to let you spin it faster.

Thanks i'll give it a shot.

jafo28 said:

Thanks i'll give it a shot.

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I had the same exact problem with mine. I had a 9v power supply that left me with a small vortex. Everyone on here said as long as it keeps the yeast suspended thats all that matters, but it's more satisfying seeing it hit the bottom. After A LOT of fine tuning with the height of the fan and adding a 12v power supply, I got it to work. I ended up stacking two hard drive magnets and that was enough to keep the 1 inch stir bar from being thrown.

Got my stir plate completed last night. I don't have a stir bar yet but it wont spin a screw in my 1 gallon growler. I hope I'll have better luck when my stir bar arrives.

rack04 said:

Got my stir plate completed last night. I don't have a stir bar yet but it wont spin a screw in my 1 gallon growler. I hope I'll have better luck when my stir bar arrives.

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A screw is unbalanced... I'd love to see the stir plate that COULD spin a screw...

Anthony_Lopez said:

A screw is unbalanced... I'd love to see the stir plate that COULD spin a screw...

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I tested mine with a screw before my stir bar came in. It worked perfectly on the surface itself, but not inside a flask or bottle. Problem was, the height of the magnet wasn't close to where it had to be for the stir bar in a flask. Just be patient and you will get it. I popped the bottom off my project box and readjusted it about 20 times.

key to a stir bar is the north and south poles of the bar.

a screw doesn't have polarity like a stir bar does.

-=Jason=-

jafo28 said:

Finally got mine working. I had to put a resistor on it because my 12 volt power supply was throwing the bar. I still can't turn it up all the way, but I think i'm getting enough of a stir going on. I'll post a couple of pics to see what you guys think.

Click to expand...

I wonder if your use of the metal top is causing any interference. It's magnetism after all that runs these things. Use the plastic lid it came with. I have my first stirplate assisted starter spinning at home right now I used stirstarter.com's build though.

thinking of using an old lunch box for my stir plate box a plastic one not metal

-=Jason=-

Should work as long as it's He-Man or SMURFS

IrregularPulse said:

Should work as long as it's He-Man or SMURFS

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I was thinking Rainbow Brite or My little Pony



-=Jason=-

IrregularPulse said:

I wonder if your use of the metal top is causing any interference. It's magnetism after all that runs these things. Use the plastic lid it came with. I have my first stirplate assisted starter spinning at home right now I used stirstarter.com's build though.

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The metal plate that the fan is mounted to should be at the bottom of the stir plate, not the top. It shouldn't be interfering with the magnets.

Flomaster said:

I was thinking Rainbow Brite or My little Pony



-=Jason=-

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Hello Kitty would be a better choice.

IrregularPulse said:

I wonder if your use of the metal top is causing any interference. It's magnetism after all that runs these things. Use the plastic lid it came with. I have my first stirplate assisted starter spinning at home right now I used stirstarter.com's build though.

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Thanks for that idea, it worked. I had the metal plate on top of the plastic to try and give it more support. I guess I didn't need that. After removing the metal I was able to get a larger vortex, but the bar was still getting thrown at top speed so I adjusted the fan a little closer to the top of plate, and now I get full speed and a 2-3 inch vortex.

This build, as is, should work. If you use all the parts listed, it should work. What it needs is some tweaking, not more parts. once i had this thing built and running, I took it apart 4 or 5 times before it actually worked right. For me, tweaking the distance of the fan to the top of the box was what got it working right. IIRC, i even put up some pictures of it pages back. I did omit the SS washer and glued the magnet right to the fan, and mine still works. I guess the epoxy I used wasn't quick drying, and I was able to move it after it was glued down to get it dead center. If you put it together and it doesn't work, tweak the distance a little until you get it right. The extra parts really aren't necessary.

well I used a 2.5" hole saw and some 3/4 MDF to cut a circle. I will countersink my magnets into the wood and center that on the fan. I will then find the "sweet spot" the fan needs to be.

-=jason=-

I have a strange situation with my stir plate..... I have a 1 in bar and in a 1l flask it spins like crazy and works just fine...... I just picked up a 2L flask..... filled it with water... dropped the bar in.... and I cant keep the stirbar from being tossed........ if I push down a little I can keep it spinning but as soon as I let up on the pressure a little the bar gets thrown..... it just puzzles me that it works great in a 1L flask but not at all in a 2L flask..... any suggestions?

backdeckbrewery said:

I have a strange situation with my stir plate..... I have a 1 in bar and in a 1l flask it spins like crazy and works just fine...... I just picked up a 2L flask..... filled it with water... dropped the bar in.... and I cant keep the stirbar from being tossed........ if I push down a little I can keep it spinning but as soon as I let up on the pressure a little the bar gets thrown..... it just puzzles me that it works great in a 1L flask but not at all in a 2L flask..... any suggestions?

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More than likely, the bottom of the 2 liter flask is either thicker or more convex which positions the stir bar farther away from the magnet(s) on the motor. The solution is to move the motor and magnet(s) closer to the bottom of the flask if possible. Less likely is that the stir bar itself has been compromised. A stir bar can become de-magnetized under certain conditions. This can happen if it is subjected to a strong shock of some kind as might occur if it were dropped on a hard floor. Heat can also weaken the magnetic properties, although I boil mine with the wort and have not noticed any problem at all and I've been doing this for a very long time. Occasionally a stir bar can be manufactured poorly with the magnet not well centered inside the teflon cover, but this is quite rare IME. I have had one 2" bar that would get thrown much more easily than other identical bars and that's the only reason that I can think of that this happens. So, the first thing to try would be moving the motor closer to the platform. Since you said it works better when you push down on the flask, that's pretty strong evidence that the distance from the motor is the problem.

the motor is as close as it can get.... it ticks the top of the box just a little.... I have a feeling that it might be spinning too fast... I have a 12v powersupply with a pot inline..... it is turned all the way down..... I was thinking of adding another magnet possibly and see if that works or maybe switching to a lower power supply...... I tried a 2 in bar as well and it throws that too...... it is just strange that both bars work just fine in the 1L flask but not the 2L.......I also wonder if thickness of the liquid will make a difference too.... it seems when I have yeast in there not just water it spins slower..... which makes sense.....I will keep playing with it.... just wondered if anyone else has had the same experience.... Thanks for the advice

BDB,

Spinning too fast can certainly cause the bar to be thrown. It's also not good for the yeast from what I have read. If you cannot move the motor closer to the platform, then stronger magnet(S) may be the best alternative. The viscosity of the wort/yeast solution will make a considerable difference and the bar will spin more slowly. This may actually be a benefit if the bar is spinning too fast now. I have had much better luck using two rare earth magnets than with a salvaged hard drive magnet. When using two magnets, it's important to space them properly and the optimum spacing will vary with the size of the bar. I have mine positioned to match a 2" stir bar. I'm running an AC muffin fan using a light dimmer for speed control with scary strong rare earth magnets. It runs silently and I don't have any problems with it throwing the bar. I can also run it with a 1-1/2" stir bar or one of the cross shaped 1-1/2" style, but the best stirring action at low speed is with the 2" bar.

I have some small rare earth magnets.... I might pull the hd magnet i have on there now off and try the smaller disc magnets..... I think I have 8 of those..... should be enough..... I will fill you in if it works.

Thanks again!

I bought a prebuilt PWM circuit to control my BK heater. The real purpose of this thing is DC motor control. So I tested on a computer fan and it works amazingly well. It would be the right thing to use to control the speed of a stirplate.

The circuit only cost about $15 after shipping, which is twice the price of the circuit itself. Although I am getting by with the simple POT for s dial now, I may switch to this other thing. It only took about 1/2 hour to solder up a few components.

It will turn the fan from almost nothing (well, a complete stop. but there is a point where it will only turn so slow before stopping) and full speed and anywhere in between.

backdeckbrewery said:

the motor is as close as it can get.... it ticks the top of the box just a little.... I have a feeling that it might be spinning too fast... I have a 12v powersupply with a pot inline..... it is turned all the way down..... I was thinking of adding another magnet possibly and see if that works or maybe switching to a lower power supply...... I tried a 2 in bar as well and it throws that too...... it is just strange that both bars work just fine in the 1L flask but not the 2L.......I also wonder if thickness of the liquid will make a difference too.... it seems when I have yeast in there not just water it spins slower..... which makes sense.....I will keep playing with it.... just wondered if anyone else has had the same experience.... Thanks for the advice

Click to expand...

I'm also having the same problem. I'm also using a 12v powersupply, 2L flask and 2 HD magnets. The bar will get thrown even with the speed turned down to the lowest setting. I was going to add another magnet or two tonight. If that didn't work I was going to change out the power supply for one with a lower voltage.

the small button magnets I scored at ace hardware in post number 492 are extremely strong. I'll be using two per side, but I could actually use 3 if need be.

call your local hardware store and see what they have. Big Box store like Lowes or Home Depot didn't have a good selection of magnets.

-=Jason=-

She's a spinning now..... I ended up taking 1 HD magnet off and adding 4 small disc magnets and it works great....I still might end up swapping out the power supply because even at the lowest speed it sucks the vortex to the bottom making a gurgling sound..... I have a feeling it wont do that when there is yeast in there because the viscosity of the liquid will be much higher causing it to spin slower..... I am just happy it is working.

Can there be "too much" stirring action? My stir plate is set on the slowest setting and there is significant movement in the glass.

Just finished up this project last night, it seems to work great although I think its under powered. When I turn it up on high I get about a 2" vortex and thats with just water. I think the cell charger I was using is 6vdc, but I just found another one thats 9vdc I'll try that tonight. But other than that, this is a great cheap and easy project. PROST! So easy a caveman could do it.

So here's what I got. Cellphone charger via the pot, varies 3vdc to 5vdc. So maxed out I get about
11/2 inch vortex with water. I just tried a 9vdc it goes from 7-9 vdc on the pot. But even at 7 vdc (minimum ) it throws the stir bar. So I guess I'll try the smaller one first, and if need be due to viscosity , I can move up to the 9vdc one.

I am trying to build this stir plate. I bought the parts at Radio Shack and pulled a fan out of an old computer. The rheostat slows the fan down but it still spins much faster than necessary and more than the stir bar can take. Any suggestions to slow the fan speed more?
Thanks!

paull390 said:

I am trying to build this stir plate. I bought the parts at Radio Shack and pulled a fan out of an old computer. The rheostat slows the fan down but it still spins much faster than necessary and more than the stir bar can take. Any suggestions to slow the fan speed more?
Thanks!

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You can limit the electricity going into the stirplate. Cheaper cellphone chargers (think 10 dollar prepaid phones) have lower electricity levels. Otherwise, you may want to look at how big your stirbar is. I have a small one that works really well, but my 2 inch one won't hold onto my magnet configuration... So there's that.

I used an Xbox 360 for my stirplate


http://i1100.photobucket.com/albums/g401/Cstgrd1/My New Stirplate/Stirplate2.jpg

Cstgrd1 said:

I used an Xbox 360 for my stirplate


http://i1100.photobucket.com/albums/g401/Cstgrd1/My New Stirplate/Stirplate2.jpg

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Airlock off, buddy....you need O2 exchange

paull390 said:

I am trying to build this stir plate. I bought the parts at Radio Shack and pulled a fan out of an old computer. The rheostat slows the fan down but it still spins much faster than necessary and more than the stir bar can take. Any suggestions to slow the fan speed more?
Thanks!

Click to expand...

I thought the same thing, but the wort was much thicker than water. With wort in there, it's good!

Get the stir bar to not get thrown by making the magnet closer to the top of the box.

What do you do when it starts offgassing(sp?) Co2?

Kayos said:

Airlock off, buddy....you need O2 exchange

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Sorry, new to this...What do you do when it starts offgassing(sp?) Co2?

I built a stir plate and made my first starter today. I had so much foam I need a blow off tube for a 2000ml flask. Normally I only have a few inches of foam in flask, it seems to really made a difference.

I was going to use one for my next starter as i had to carefully adjust the speed to keep the foam to a minimum(i still had to clean the airlock twice)...If there is Co2 in the beaker then how would oxygen get to the yeast after fermentation began anyhow?

Cstgrd1 said:

I was going to use one for my next starter as i had to carefully adjust the speed to keep the foam to a minimum(i still had to clean the airlock twice)...If there is Co2 in the beaker then how would oxygen get to the yeast after fermentation began anyhow?

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Because it is being stirred the head space is not a stable place for co2 to form a layer but rather a turbulent place that remains in motion due to the friction between the moving liquid and the air in the head space. Loosely capping the flask with foil (or using an autoclavable foam stopper) will allow air exchange but prevent contaminates from getting in. Remember bugs don't fall up!

+1 the main reason for the stir plate is to aerate and allow the yeast to grow (multiply) faster.

EDIT: maybe faster isn't the right word...

Cstgrd1 said:

I used an Xbox 360 for my stirplate


http://i1100.photobucket.com/albums/g401/Cstgrd1/My New Stirplate/Stirplate2.jpg

Click to expand...

LOVE the xBox....