stir bar spins on end

I am finishing up my DIY Stir Plate. Everything works great, with one exception. When the fan spins the stir bar, the stir bar stands on end. The magnet used is a block magnet from home depot. Plenty strong. Pulls the bar to where ever I hold the magnet . I was wondering, is the magnet too strong or do have to dial down fan speed. I have a reostat but have not installed it. Just doing a rough in to ensure everthing works. A direct connection from the power source to the fan. Can anyone tell me if I'm doing something wrong? Could too high of fan speed be the culprit? I'm very frustrated. Tried button magnets and he bar would not turn. Thanks for the input.

It might be how the magnets are polarized, I had the same issue, finally got a couple of magnets that worked correctly.

jkaylor said:

It might be how the magnets are polarized, I had the same issue, finally got a couple of magnets that worked correctly.

Click to expand...

I agree. If the bar stands stait up, it has to be a polarity problem. The stir bars are magnetized as well and the magent you have must have the same polarity as the stir bar and it is pushing it away instead of attracting it.

Its probably been magnetized. you can try to demagnetize it by rubbing it on your strong magnet in random directions trying not to do the same direction each time. Either that or a tape demagnetizer if you have one. or buy a new one. You shouldn't have a problem of your magnet being to strong.

ryan0914 said:

Its probably been magnetized. you can try to demagnetize it by rubbing it on your strong magnet in random directions trying not to do the same direction each time. Either that or a tape demagnetizer if you have one. or buy a new one. You shouldn't have a problem of your magnet being to strong.

Click to expand...

Demagnetizing the stir bar will cause it to be worthless. You need either a magnetized stir bar or a ferrous stir bar so that the magnet can grab it. If there is no attraction, the stir bar won't spin.

It would probably just be better to buy a new one. You can find them on eBay for pretty cheap.

These are listed on Ebay for $4.99



5 NEW stir bar/mixing bar / magnets | eBay

jkaylor said:

These are listed on Ebay for $4.99



5 NEW stir bar/mixing bar / magnets | eBay

Click to expand...

Wow, yet another reason to hate my lhbs. I looked into buying a stirplate a couple of weeks ago. They wanted $120. I built one for $6.00.

I bought A, ONE, SINGLE stir bar for $6.25.

I had the same problem when I built my stirplate, you need to use magnets with a north and south opposite each other. I first used ones that had opposite poles next to each other and were a rectangle shape. Try using different magnets with your stir bar and see what ones make the bar lay flat and not stand up.

Slow down the fan speed and it should work.

Sounds like a polarity issue to me too. I'd try getting a second magnet and attach them to a large fender washer, then attach the washer to the fan. Double-check your polarity before putting it all back together to make sure the stir bar hooks up and centers itself on the axis and is not repelled at either end.

Here's a pic of mine if it helps. The magnets have a slight curve to them so one is attached to the washer with the curve up, and the other with the curve down.

Another vote for polarity

jiggs_casey said:

Wow, yet another reason to hate my lhbs. I looked into buying a stirplate a couple of weeks ago. They wanted $120. I built one for $6.00.

I bought A, ONE, SINGLE stir bar for $6.25.

Click to expand...

Care to share the stir bar you built?

microbusbrewery said:

Sounds like a polarity issue to me too. I'd try getting a second magnet and attach them to a large fender washer, then attach the washer to the fan. Double-check your polarity before putting it all back together to make sure the stir bar hooks up and centers itself on the axis and is not repelled at either end.

Here's a pic of mine if it helps. The magnets have a slight curve to them so one is attached to the washer with the curve up, and the other with the curve down.
<img src="https://www.homebrewtalk.com/attachment.php?attachmentid=41531"/>

Click to expand...

It has to be like this. Two separate magnets in the stir plate. I tried with one long bar magnet with the same results as you. I snapped it in half, and mounted with proper polarities and it worked great.

the magnet you are using is polarized top to bottom rather than end to end. The stir bar is polarized end to end ( I cant recall the terms for this) .. Basically the surface of the magnet that is facing you and towards the stir bar is eaither N or S .. the stir bar on the other hand has one END that is N and the other S. That is why one end of your bar is attracted and the other repelled. Get a different magnet, or 2 seperate ones..or break the one you have in half.

nukinfuts29 said:

Care to share the stir bar you built?

Click to expand...

The stir plate?

I need to get pics of it but mostly, I used parts I had on hand.

I took a generic power supply that I bought years ago, the kind that you can use for a multitude of different devices (variable voltage, polarity and a bunch of different connectors, it was the only one I had on hand that would do 12 dc volts, and wired it to a 80mm PC case fan that I bought from Microcenter ($.99) and then wired a 25-ohm, 3 position rheostat, from Radioshack, into it ($3.95) in as well. I mounted the fan into a desktop mesh bowl that I used to keep loose change in and glued a hard drive magnet to it.

I need to pick up a flask but, as 'proof of concept', I took a plastic measuring cup, put a couple cups of water in it and dropped in the stir bar. I let it run for a couple of days to see if it would burn out and it seemed to work okay!

First time I read through here I thought you said stir bar, which peaked my curiosity big time lol.

I built a stir plate using 1 hard drive magnet. Any stir bar I use over 3/4" will stand up on end when the plate is running. The 3/4" stir bar will stand up at high speed. A 5/8" stir bar doesn't do this and a 1/2" stir bar works the best on my stir plate.

all good info to keep in mind. didn't have a prob when i made mine with a hard drive magnet but I don't think my stir bar is bigger then .5".