DIY Stir Plate Question

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mmurray

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My local Radio Shack only has Ceramic Magnets. Everywhere I read everyone is using rare earth. Do they have to be rare earth Magnets?

Thanks
 
Thanks for the input, but it didn't answer my question...

Suppose for a minute that I did not have an old hard drive... access to an old hard drive... or anyone who has any old hard drives.

Now... would a ceramic magnet work or do they have to be rare earth?

Thanks again.
 
Ceramic magnets will work just fine so long as they are of sufficient strength. I use super strong rare earth magnets purchased on line, but you can get by with any fairly strong permanent magnet. Aligning, spacing and balancing the magnets properly is critical for these DIY stir plates. The puny stir bars are the easiest to work with. The larger bars (2"+ sizes) are much trickier to use, but they do a better job of stirring IMO.
 
Ok, thank you... Now I suppose I just need to find out what the strength of the magnets are at Radio Shack
 
Go to a computer repair shop and ask them for a bad drive they will have some..
open it up and there you go tow nice and free thin rare earth magnets,,
just try not to break them taking them out,, get a couple of drives
 
I guess we did do a pretty ****ty job of 'answering' other than Catt22 (props)

I highly suggest going online and buying a nice strong magnet for the same price as the ceramic magnets at RS. The stronger the magnet (in my experience) the less precisely they must be centered for the stirbar to not fly off at speed. But keep in mind if its TOO strong, you could mess up the fan (maybe?) or make it hard for it to spin due to friction and possibly weight. Just my 2c
 
NoNothing said:
I guess we did do a pretty ****ty job of 'answering' other than Catt22 (props)

I highly suggest going online and buying a nice strong magnet for the same price as the ceramic magnets at RS. The stronger the magnet (in my experience) the less precisely they must be centered for the stirbar to not fly off at speed. But keep in mind if its TOO strong, you could mess up the fan (maybe?) or make it hard for it to spin due to friction and possibly weight. Just my 2c
Click to expand...

+1 The rare earth magnets are not at all expensive to purchase online. Get a couple of your brewing buddies together and do a piggy back order to offset the shipping costs. I tried the hard drive magnet route. It was a hassle and the curved magnets were difficult to mount and balance. IMO, not worth the trouble. OTOH, lots of people have had success using them.
 
I tried the ceramic magnets prior to ripping open an old computer. They sucked, hence I ripped open an old computer. Hope that helps.

Another source is one of those "shake" flashlights. That is what I am using right now.
 
Thanks guys... didn't mean to sound like a D!ck... I just don't have any extra HD's and like I said before... Radio Shack only had the Ceramic.

I look at the Rare earth Magnets from an advertiser on this site, but the minimum order was 50. Granted... 50 were only $9 + S/H... but what am I going to do with 48 extra magnets?

It's more about not wanting to waste a bunch of magnets than the money...
 
I was able to find a good selection of magnets after the fact at ACE hardware if there is any close to you.
 
On a side note, I just ordered a 10 pack of those 2mmx20mm RE magnets from deal express, $5, and if they're **** who cares for that price.

They failed to list their strength, so I dont have SUPER high hopes, just that they might be better than my current setup
 
You will want the strongest magnets you can find, and that would definitely be rare earth. You should not have to buy them online... check craft stores or even hardware stores. I used to use the Hard drive magnets but switched over to small round ones that I stack to get max magnetic field. I've built a few of these and I can assure you the fan will not be affected by the fields.
 
Homercidal said:
PM me and I will send you a couple of HHD magnets. I have "a few". Just pay for the postage.
Click to expand...

I've considered taping my little round ones inside an envelope. Then I had this mental image of the envelope getting hopelessly mangled inside the metal mechanisms of a high-speed sorter at the post office.

You might want to put inside a small box if you ship.
 
Thanks for the offer. I'll check my local Ace first and then a few other hardware stores.

I think there might be a computer repair shop on my way to work... just not sure if they are still open or not.
 
I used one at first, it threw the stir bar more than I'd like to say. I balanced two magnets on a fan and they have worked great for me!
 
BierMachen said:
I used one at first, it threw the stir bar more than I'd like to say. I balanced two magnets on a fan and they have worked great for me!
Click to expand...

Yep, same here. I ended up stacking 3 hd magnets to get it to work right, but now I've found the two stacks works much better too. Just make sure that when you fix the two magnets to your fan, one is flipped over to you have opposite poles.
 
extra_medium said:
what is the beneifit of using more than one magnet? can't i just have one centered on the center of the fan?
Click to expand...

You would have to get one with poles at different ends, not different sides of the magnet.

(these are all side views)
Computer magnet have 2 N and 2 S poles. They look like this from the side:
NNNNNNNNSSSSSSSSS
SSSSSSSSNNNNNNNNN

so they grab the stirbars which are:
NNNNNNNNSSSSSSSSS

If you get a coin shape magnet most likely it is this:
NNNNNNNNNNNNNNNNN
SSSSSSSSSSSSSSSSS

which will not work, it wont grab right. I cant remember if it was this thread or another one but someone said they were using 2 magnets with both north poles facing up, same problem, wont work:

NNNNNN NNNNNN
SSSSSS SSSSSS



So computer hard drive magnets are favored for their ability to work by just putting them on the fan, any way you flip them, they work, simple as that.

With most other magnets you will need two to get the polarity right to grab the stir bar.

Hope that helps.
 
mmurray said:
Thanks for the input, but it didn't answer my question...

Suppose for a minute that I did not have an old hard drive... access to an old hard drive... or anyone who has any old hard drives.

Now... would a ceramic magnet work or do they have to be rare earth?

Thanks again.[/QUOTE

I tried their ceramic magnets and didn't work. The strength is needed when doing starters to really hold the stir bar. I bought mine from kj magnetics. they are cheap and I got them in 2 days in the mail.]
Click to expand...
 
I have the coin shaped magnets and you have to make sure you check the poles and put the oposite pole acros from one another. Duhh my stir plate wont work. Why is the stir plate virtical in my flask? Duh! flipped the magnet on the other side and hey it works. Was glad no one was around at the time. :eek:
 

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