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Old 02-19-2013, 05:54 PM   #1
BrokenDog
 
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Hey guys I was inspired to build a sitr plate after reading some of the how-to but I'm not sure that it's moving fast enough. Usually I have to push start the fan blades to get it moving and at max speed I only get a small dimple. Check out the video and tell me if there is anything I could change to speed it up. The guts are a 120mm 12v fan, 5v phone charger, 25 pot, and 1 hd magnet. BTW the magnet is about an inch off the surface of the fan so interference shouldn't be an issue.
http://youtu.be/PlgIPyZu_dY
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Old 02-19-2013, 06:53 PM   #2
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A small dimple is all you need, but you might try a 6V adapter if you would like it to go faster. 5V is right near the edge of working for some fans.

 
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Old 02-19-2013, 06:55 PM   #3
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But if you want more voltage try a 12v and you should get more, it is a 12V fan after all and you have control of it

 
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Old 02-19-2013, 07:13 PM   #4
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I wonder if you have too much pull between stirbar and magnet. It would be easy to test putting something like a small piece of cardboard under the flask to create a slightly larger space between stirbar and magnet to see if a little less attraction help or hurts. I find that wort with yeast makes the stirbar seem as though it's in mud; i.e. it slows it down. I almost wonder if you be able to tell that it's moving once you can't see into the liquid.

One other option would be to put a small oring on the stirbar, in the center, to create a balance/fulcrom point. This should reduce the friction of the stirbar on the glass and make it much easier to spin.

Overall, I would say you've created a very nice stirplate; just need to dial-it in a tiny bit. Love the POT and power switch; and the heady topper sticker too
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Old 02-19-2013, 08:49 PM   #5
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I think you need more voltage. The bar is barely spinning, and you need a vortex to form to get efficient gas exchange
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Old 02-19-2013, 08:54 PM   #6
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That's not correct. All you need is a small dimple in the surface, indicating that you're constantly turning the liquid over. If you go too fast, you'll actually damage the yeast cells, and a vortex is *way* too fast.

 
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Old 02-20-2013, 12:50 AM   #7
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Quote:
Originally Posted by stpug View Post
I wonder if you have too much pull between stirbar and magnet. It would be easy to test putting something like a small piece of cardboard under the flask to create a slightly larger space between stirbar and magnet to see if a little less attraction help or hurts. I find that wort with yeast makes the stirbar seem as though it's in mud; i.e. it slows it down. I almost wonder if you be able to tell that it's moving once you can't see into the liquid.

One other option would be to put a small oring on the stirbar, in the center, to create a balance/fulcrom point. This should reduce the friction of the stirbar on the glass and make it much easier to spin.

Overall, I would say you've created a very nice stirplate; just need to dial-it in a tiny bit. Love the POT and power switch; and the heady topper sticker too
I've played with the spacing a bit, I put a towel in between and tried 1-3 folds, they didn't seem to make a difference in spin, but 4 folds was too much to turn the bar.
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Old 02-20-2013, 12:52 AM   #8
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I"ll be on the lookout for a power supply with more volts although I know I've read about others on the forum using 5v and can pull a full vortex. Is it possible that there is something I could have wired wrong to get spin but not enough? I don't see how that's possible but I also don't know anything about electricity.
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Old 02-20-2013, 02:09 AM   #9
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My DIY stirplate uses a 5v power adapter, 80mm fan, has a built-on potentiometer, split hard drive magnets, and spins from medium to very fast. I can't actually go as slow as yours but never have needed to either; then again, the fastest setting is way too fast.

How fast, in comparison, does the fan spin if you remove the top and just watch the magnets spinning. Is it about as fast as the stirbar or much much faster? I expect it to spin faster but I'm wondering about how much faster. On mine, if I just spin the fan and magnets it's much much much faster. If I spin with water then it's pretty fast on it's lowest setting, and if I do a proper starter then it's decently slower than water.

The only thing in your system that I can think would slow you down is the potentiometer. Is it possible to try running without the POT in the loop just to compare your 'high' speeds (with and without POT)?
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Old 02-20-2013, 03:48 AM   #10
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Quote:
Originally Posted by stpug View Post
My DIY stirplate uses a 5v power adapter, 80mm fan, has a built-on potentiometer, split hard drive magnets, and spins from medium to very fast. I can't actually go as slow as yours but never have needed to either; then again, the fastest setting is way too fast.

How fast, in comparison, does the fan spin if you remove the top and just watch the magnets spinning. Is it about as fast as the stirbar or much much faster? I expect it to spin faster but I'm wondering about how much faster. On mine, if I just spin the fan and magnets it's much much much faster. If I spin with water then it's pretty fast on it's lowest setting, and if I do a proper starter then it's decently slower than water.

The only thing in your system that I can think would slow you down is the potentiometer. Is it possible to try running without the POT in the loop just to compare your 'high' speeds (with and without POT)?
It doesn't seem to spin much slower w/o the stir bar. I guess it could be the size of the fan since yours is 80mm and mine is 120mm. Trying to run a direct feed is an interesting idea although everything is soldered in so I want to make sure I've eliminated all my other options first.
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