Does a longer stir bar get thrown less?

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zanemoseley

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So I have a shorter stir bar (about 1") and I've been doing large 1 gallon starters in an old pickle jar. The first time I had to turn down the speed so it wouldn't get thrown. Now on my second starter with the same bar and jar I can't get the bar to stay spinning more than a couple seconds. I really like this jar but can't get the stir bar going, I have no idea why I got it fine before but can't get it now. Will a long bar help or will it be the same?
 
I've never tried a 2"bar. I use a 1" in my pickle jar. I think the Idea is to use a bar that has the same spacing in the bar magnets as the magnet spacing on your stir plate. My procedure for getting the bar to stay spinning is to 1st use a magnet to locate the bar to the center of the jar. I then place it as close to center of the stirrer as I can and start off slow. I've gotten used to knowing if it's close to centered by the sound it makes. I turn the stirrer up enough to see the whirlpool on top and make slight moves to get it centered. When I'm confident I have it centered I turn the plate up and keep an eye on it . Sometimes it's another slight adjustment. When I'm done I have a nice dimple in the center, It's not making too much noise, and it will run forever.
 
I've never tried a 2"bar. I use a 1" in my pickle jar. I think the Idea is to use a bar that has the same spacing in the bar magnets as the magnet spacing on your stir plate. My procedure for getting the bar to stay spinning is to 1st use a magnet to locate the bar to the center of the jar. I then place it as close to center of the stirrer as I can and start off slow. I've gotten used to knowing if it's close to centered by the sound it makes. I turn the stirrer up enough to see the whirlpool on top and make slight moves to get it centered. When I'm confident I have it centered I turn the plate up and keep an eye on it . Sometimes it's another slight adjustment. When I'm done I have a nice dimple in the center, It's not making too much noise, and it will run forever.

That pretty much sums it up, unless you have a perfectly flat bottom like Malfet said. I don't think a larger stir bar will solve your problem. Sounds like either the bottom of the jar is too irregular or your magnet placement is off a little bit. You want to get the magnet as close to the bottom of the jar as possible. I had to sort through about 30 or 40 gallon jugs at the local fruit market to get a handfull that were suitable for stir plate duty. Once you find a good one, don't drop it. My brew buddy dropped one of mine the other day. Now I'm using a back up that makes a lot of noise and throws bars like crazy if you don't get it centered just right.
 
My 2L flasks get 1.5 or 2" bars. My growlers get 1" or .75" bars. Dont forget the spacing of your magnets also plays a factor!
 
I find that starting at a slower revolution setting and gradually increasing the speed on the stir plate reduces the chances of throwing the stir bar. Small stir bars unless I’m making a 4 to 5 liter starter than I jump to the two inch stir bar.
 
I find that starting at a slower revolution setting and gradually increasing the speed on the stir plate reduces the chances of throwing the stir bar. Small stir bars unless I’m making a 4 to 5 liter starter than I jump to the two inch stir bar.

What kind of vessel are you making 5 liter starters in? Hopefully something cheap, because I'd like to get one. :mug:
 
A shorter bar would help with the throwing issue. My stir plate has a magnet pretty much it's entire diameter so I rarely have an issue.

You don't need a vortex at the surface to promote growth. A subtle agitation should suffice in introducing oxygen
 
I had a real problem with using a hard drive magnet. Is that what you're using? It has a curve and the magnetic field is a little tricky. The magnetic field is not exactly centered its off a little bit to the inside of the curve. This of course put my magnet just a little off center of the fan so it can vibrate and move a lot if not weighted down with a starter flask. I had to put a 1 inch PVC spacer between the fan and magnet so the magnet would not lock the fan down, so that further increased the trouble with finding center. So finding the exact center was a daunting task. I ended up just buying a 1 inch stir bar because the 1.5 was being thrown all the time.

My Homemade stir plate.
 
I guess I'm lucky then? I have a heated stir plate I picked up on eBay in a $25 BIN. I suspect someone typod and was too embarrassed to admit it - it even came with a small tray of bars
 
What kind of vessel are you making 5 liter starters in? Hopefully something cheap, because I'd like to get one. :mug:

It doesn't get much cheaper than a free cake icing bucket (2 gallon). I get mine from Sams Club. Just ask at your local store that sells decorated cakes.

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So I was having stir bar problems too and was thinking of solutions.....then it came to me!

My wife was wearing braces (teeth not leg) and she has to wear elastics to connect different teeth. The suckers are small! Maybe 1/4 inch round when not stretched. Hmm...good for mouth, must be ok for beer. I put 2 on the bar. One on each end as far apart as I could get it. And, holy ****! It worked!

They act like wheels, it now spins faster, makes less noise and became a free fix! Full vortex in a 2 liter flask.
 
It could be that you're expecting to much stirring from the plate- you do not need a full vortex, just a "dimple" at the top. The goals of a stir plate are taking CO2 out of suspension, gas exchange, and keeping the yeast in suspension. Constant stirring at a moderate level will accomplish this.
 
In the lab, we use 3/4" bars with a raised " ring" around the center of the bar. slow, fast, any speed never a problem. I am finding out that the POS HBS stir bars "chatter" from the friction and tend to throw the bar. Get a lab quality bat and be don with it...
You can get the cheaper than this but heres some examples...
http://www.labdepotinc.com/Product_Details~id~336~pid~60354.aspx
 
What kind of vessel are you making 5 liter starters in? Hopefully something cheap, because I'd like to get one. :mug:

:off: sorry OP.
I have a couple of Cambro 22 Quart clear round containers. Great for water measurement and large starters. They cost around twenty-four bucks a piece.
 
+1 on the raised ring at the center of the bar. I think they call it a centering ring. I used to have the same problem and I switched to this style stir bar and haven't had the same problem again. I just made a 3 gallon starter for a 15 gallon batch of Russian imperial stout and I used a 200mm stir bar with a centering ring. Despite the bottom of my vessel being a slight imperfect dome it plowed right through with no problems.
 
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