Stir bar problems

[rhoffmann79]

I just made my first stir plate and after messing around with the magnets I was able to get the stir bar to spin without being thrown. The new problem I have is that once I put the stir bar in liquid it won't spin. I was wondering if this was a problem with the bar or the magnets not being strong enough. HELP!

 

[Brett3rThanU]

What type of magnets did you use? How much space is between the magnet and the stir bar? Does the fan spin?

 

[DaDzBrewery]

I just made my first stir plate and after messing around with the magnets I was able to get the stir bar to spin without being thrown. The new problem I have is that once I put the stir bar in liquid it won't spin. I was wondering if this was a problem with the bar or the magnets not being strong enough. HELP!

You might have the fan too high, and when you put the weight of the liquid on the stir plate, then it's compressing down and keeping the fan from spinning..

 

[rhoffmann79]

What type of magnets did you use? How much space is between the magnet and the stir bar? Does the fan spin?

I used 1/4x1/4 rare earth magnets. the space between the two is nominal I have the fan pushed up inside the case almost as far as it will go. I would say there is about 1/4 to 1/2 inch space between bar and magnets with it in the jar. And yes the fan spins great. Everything works as it should if i put the bar directly on the stir plate or in an empty jar. It just won't spin if I add liquid to it

 

[DaDzBrewery]

I used 1/4x1/4 rare earth magnets. the space between the two is nominal I have the fan pushed up inside the case almost as far as it will go. I would say there is about 1/4 to 1/2 inch space between bar and magnets with it in the jar. And yes the fan spins great. Everything works as it should if i put the bar directly on the stir plate or in an empty jar. It just won't spin if I add liquid to it

Did you reverse the magnets ? By seeing which sides attract and push, then put one upside down.. So they both will attract each end of the stir bar...

 

[rhoffmann79]

Did you reverse the magnets ? By seeing which sides attract and push, then put one upside down.. So they both will attract each end of the stir bar...

Yes I did that. It spins correctly it just doesn't seem to have enough strength to spin through the wort

 

[rhoffmann79]

Did you reverse the magnets ? By seeing which sides attract and push, then put one upside down.. So they both will attract each end of the stir bar...

Yes it spins fine it just doesn't seem to have enough power to spin in liquid

 

[rhoffmann79]

You might have the fan too high, and when you put the weight of the liquid on the stir plate, then it's compressing down and keeping the fan from spinning..

I checks and the fan still spins with the liquid on the plate. The stir bar just doesn't seem to have enough power to spin while in the liquid. Thanks for the idea though

 

[RUNningonbrew]

Did you use 1 or 2 magnets? Are you using a regular stir bar? I know this is a
Dumb questions but are you able to see to make sure the magnet is sitting in the middle of your jar with the wort in it? I know I have to play around with mine for a little bit to get it to go to the middle

 

[dbrewski]

How long is your stir bar? I bought one that was 1.5" (I think) and it didn't work very well. I eventually bought a stir starter, which I love and if you have $40 lying around it is totally worth it, but my point is this: it came with a teeny little stir bar! I thought, this thing won't work! Boy I was wrong. So I was thinking if you are currently using a big one, you could try smaller.

 

[DaDzBrewery]

I checks and the fan still spins with the liquid on the plate. The stir bar just doesn't seem to have enough power to spin while in the liquid. Thanks for the idea though

Maybe you have the fan too low.. ( too far from the bottom of the jar ) and when there is restriction, then the magnets are just out running the stir bar. ?

 

[RUNningonbrew]

Are you using a beaker? My homemade stir plate only worked properly when I bought a 2000 ml beaker .

 

[JefeTheVol]

You said the space between the magnets is "nominal" meaning what? If you mean trifling or negligible then you need to space your magnets apart. Putting them too close together will cause your magnetic fields to interfere with each other and the stir bar wont spin well. I think you need to space your magnets out a little more and you might have a better result.
-Jeff-

 

[aubiecat]

When I built my stir plate I used four 3/8" rare earth magnets, two stacked on top of each other. I built it with a 1" stir bar in mind so my magnet centers are exactly 1" apart.

 

[Hang Glider]

^ this, but I used 1/2" magnets

 

[Rudolph]

I just finished my stir plate tonight. I had the exact same problem at first. I narrowed it down to magnets being to weak. I didn't want to buy another stir bar so I bought these rare earth magnets: http://www.rare-earth-magnets.com/p-43-nsn0641.aspx They each pull about 10 pounds and I'm using two. Needless to say, my bar no longer gets thrown. In fact, I can hold the flask an inch above the plate and it still spins centered.

As for spacing: I made it to where about 1/4 of the magnet extends past the bar. But honestly I don't think the spacing matters with that powerful of a magnet. IMHO balancing them is more important.

 

[airving]

When you put the flask + liquid on top of your stir plate ( turned off, at this point) does the stir bar jump into alignment with the magnets?