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Old 07-05-2012, 05:32 PM   #1
brewzofo1
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Dec 2011
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My DIY stir plate is completed. But I cannot get my stir bar to spin inside my 2 quart Pyrex with water. The stir bar works fine when I place it directly on top of the stir plate. I have a 2" stir bar with a small round ring in the middle. The bar is inside a clear vinyl beer line because of the middle ring. Like I said it spins fine directly on the plate.
Thank you.

 
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Old 07-05-2012, 05:37 PM   #2
emjay
 
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Stronger magnets or slower fan speed. And the ring is used as a pivot point... take it out of the beer line.

 
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Old 07-05-2012, 05:40 PM   #3
kh54s10
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Quote:
Originally Posted by brewzofo1 View Post
My DIY stir plate is completed. But I cannot get my stir bar to spin inside my 2 quart Pyrex with water. The stir bar works fine when I place it directly on top of the stir plate. I have a 2" stir bar with a small round ring in the middle. The bar is inside a clear vinyl beer line because of the middle ring. Like I said it spins fine directly on the plate.
Thank you.
Why do you have the bar inside the beer line? The middle ring on the stir bar is there to help it spin. Sometimes it helps, sometimes it doesn't.

First, try it without the beer line, then try adjusting the magnets. Sometimes the height of the fan will also make a difference.

It might just take some experimentation to find out what works.

 
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Old 07-05-2012, 05:41 PM   #4
carlisle_bob
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Apr 2012
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Hi

I'm not getting a real good mental image of this setup so pardon the somewhat generic reply...

1) The magnets on the fan may be to far away from the bar once the pyrex spaces the bar up off the table. Check it with an empty pyrex.

2) The magnets may not be powerful enough once water is involved.

3) The fan may be running to fast, try the slowest setting on your speed control first.

---------

now for the unlikely stuff:

4) Is the fan still running with the weight of the water filled pyrex bending everything?

5) Is the bar centered properly? It should snap into place.

6) Are the magnets on the fan far enough apart for the stir bar? Does it "flip out" in the water?

Lots of other strange possibilities, but that's plenty without really seeing what you have set up.

Bob

 
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Old 07-05-2012, 05:43 PM   #5
GulfCoastGirl
 
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Quote:
Originally Posted by brewzofo1 View Post
My DIY stir plate is completed. But I cannot get my stir bar to spin inside my 2 quart Pyrex with water. The stir bar works fine when I place it directly on top of the stir plate. I have a 2" stir bar with a small round ring in the middle. The bar is inside a clear vinyl beer line because of the middle ring. Like I said it spins fine directly on the plate.
Thank you.

When you put the container with water (and stir bar) on the plate ... does the stir bar snap to the middle (over where the magnet is) or does it just lay on the side of the pyrex? If it doesn't snap to the middle then either your magnets aren't strong enough or you don't have them close enough to the top of the stir plate on the inside.

Take the bar out of the vinyl... this is no good. I have a couple of bars with the middle ridge and they spin just fine.

 
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Old 07-05-2012, 05:49 PM   #6
brewzofo1
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The magnets I am using are rectangle in shape. I have two side by side (lengthwise). They are 1" each for a total of 2"
The fan with magnets attached is appr. 1/4" from the top plate. Okay I took the beer line out and put back inside Pyrex to try again. It started to spin for a second then started to jump around and then nothing.

 
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Old 07-05-2012, 05:56 PM   #7
brewzofo1
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Dec 2011
huntington beach, ca.
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Quote:
Originally Posted by carlisle_bob
Hi

I'm not getting a real good mental image of this setup so pardon the somewhat generic reply...

1) The magnets on the fan may be to far away from the bar once the pyrex spaces the bar up off the table. Check it with an empty pyrex.

2) The magnets may not be powerful enough once water is involved.

3) The fan may be running to fast, try the slowest setting on your speed control first.

---------

now for the unlikely stuff:

4) Is the fan still running with the weight of the water filled pyrex bending everything?

5) Is the bar centered properly? It should snap into place.

6) Are the magnets on the fan far enough apart for the stir bar? Does it "flip out" in the water?

Lots of other strange possibilities, but that's plenty without really seeing what you have set up.

Bob
#3) fan is appr 3" 12v and using a 12 volt cord.

#4) fan runs fine with weight of Pyrex/water on top.

#5) bar snaps into place.

#6) magnets are 2" in length. Bar is 2"

 
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Old 07-05-2012, 05:59 PM   #8
emjay
 
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Quote:
Originally Posted by brewzofo1
The magnets I am using are rectangle in shape. I have two side by side (lengthwise). They are 1" each for a total of 2"
The fan with magnets attached is appr. 1/4" from the top plate. Okay I took the beer line out and put back inside Pyrex to try again. It started to spin for a second then started to jump around and then nothing.
Like I said, you either need more powerful (or closer) magnets, or you need to slow the fan down.

 
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Old 07-05-2012, 06:01 PM   #9
carlisle_bob
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Hi

The fan needs to be running below about 750 rpm to do much good as a stir plate. Unless you have a very unusual fan, you need to add a speed control.

Bob

 
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Old 07-05-2012, 06:03 PM   #10
GulfCoastGirl
 
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Quote:
Originally Posted by brewzofo1 View Post
It started to spin for a second then started to jump around and then nothing.

A 2" stir bar is big and going to have trouble getting started. Also, if the fan spins too fast it can throw the bar. I have this same trouble with mine, although the largest bar I have is 1.5"

Even with the Rheostat set to run my fan on the lowest setting is too fast to get it going without throwing the bar.

What I do is hold my beaker about 1/2 inch over the stir plate while the spin gets going. Once it's going I can set the beaker down and it doesn't get thrown. Sometimes it takes a couple of tries.... but I can always get it spinning this way.

I don't know about that 2" bar.... you might want to get a 1" bar. You'll likely have better luck.

 
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