Stir Plate for 5L Flask

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Jsta Porter

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Hello,

Thanks, in advance!

I have a DIY stir plate, thanks to the expierence of folks on this site. It works great with 1L and 2L flasks. Once I put the 5L flask on it the bar gets kicked. The flask appears to be as flat as the rest. I use a 2" stirbar, with center ring, this one:



Is it a matter of technique, or the wrong tool for the job? Any reccomendations on stirplates for larger starters, which I find myself doing more often than not.

Thanks!
 

Anthony_Lopez

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I do gallon starters on my stirplate from the link in my signature without issues. Is it safe to assume that you are using the 2 inch bar when doing 1L and 2L starters?
 
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Jsta Porter

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Thanks- yes, safe assumption, I use a 2 inch bar on the 1L and 2L starters.

Side note- I have been meaning to go to a Wort Processors meeting. Worth it?

Thanks!!
 

Catt22

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The flask size should not really make any difference as far as throwing the stir bar. How is the stir plate platform constructed? Is there a lot of deflection when you put the much heavier 5 L flask on the platform? Does the fan/magnet stay in the same position relative to the platform with the bigger flask on it? I'm thinking that the configuration is changing with the added weight causing a less than optimum alignment etc. Other than that, I can't think of anything else except maybe try using stronger magnets.
 

homebrewer_99

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I've been having a really odd problem with my stir plate lately.

If I (halfway) fill the flask with water the plate works fine, but once I use malt it always tosses the stirbar. It worked well for almost 1 year, but now it doesn't even work for 3 seconds without tossing the stirbar.

I have 2 rare earth marnets configured like 2 cresent moons facing each other on the fan.

Any ideas what could be causing this all of a sudden? I'm stumped.:mad:
 

Catt22

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My guess is that the stir bar has lost some of it's magnetic strength. Stir bars should be purchased in pairs and when not in use they should be stuck together to preserve their magnetic properties. The malt/water solution has a higher viscosity and presents more resistance to the stir bar turning. A weak magnetic coupling between the fan magnets and the stir bar seems to be the likely source of your problem. You should also be able to fill the flask completely without problems.
 
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Jsta Porter

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The flask size should not really make any difference as far as throwing the stir bar. How is the stir plate platform constructed? Is there a lot of deflection when you put the much heavier 5 L flask on the platform? Does the fan/magnet stay in the same position relative to the platform with the bigger flask on it? I'm thinking that the configuration is changing with the added weight causing a less than optimum alignment etc. Other than that, I can't think of anything else except maybe try using stronger magnets.
I am currently using an aluminum case from the Maxtor external drive that I pulled the magnets from. There does not appear to be any flex in the platform. The base of the flask is thicker than the 1L or 2L. I will try the additional magnets and see if that makes a difference.

Thanks!
 

Anthony_Lopez

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The OP's problem definitely sounds like an issue of magnetic power. I would suggest getting some very strong magnets or adding magnets if possible.

These guys at K&J make some serious magnets. The safety warning/product disclosure is longer than their packing slip and receipt.
 
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