Stir plate problems

[zhubbell]

Okay, so I have this:

With a shallow box that goes over it and supports the starter, but I just ran a trial and it didn't work...it just rattled around a bit every few seconds....
Any advice please??


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[ph0ngwh0ng]

I never succeeded in building a stir plate with hard drive magnets. I ended up buying round neodymium magnets and gluing two on the center piece of the fan. Never had a problem since.

 

[Picker]

I would probably pry the magnet off that piece of metal it's glued to. Should pop right off, then reattach to the fan and make sure it's balanced. Also make sure your flask isn't too close to the magnet or you will have issues.

 

[Smellyglove]

I believe there is a magnet inside the fan, which makes it spin. Maybe they're counteracting eachother?

 

[kh54s10]

I agree, knock the magnet off the metal bracket. You might need to move it around to find a spot that will work. As already said you might also have to work in the vertical positioning.

I tried gluing mine on but it ended up just stuck to the metal under the plastic fan. You might also need to try different stir bars. Flat ones don't work for me. Mine needs a pivot ring in the middle. I started by putting an O-ring around the middle. Then bought a new one with the pivot ring in the middle.

I also had to work with different power converters to find one that gave the right power. I had a few from old electronics, like cordless phones and answering machines, the third one worked.

 

[Hermit]

I believe there is a magnet inside the fan, which makes it spin. Maybe they're counteracting eachother?

This is often overlooked. Find a way to raise the magnets, even if just a little bit. I have mine on a hose washer. It happened to be the same size as the fan hub so that made centering easier but I was using a bar magnet so the middle didn't matter. If my magnet touched the metal shaft sticking through the fan it stopped it dead.

 

[squash1978]

This is often overlooked. Find a way to raise the magnets, even if just a little bit. I have mine on a hose washer. It happened to be the same size as the fan hub so that made centering easier but I was using a bar magnet so the middle didn't matter. If my magnet touched the metal shaft sticking through the fan it stopped it dead.

I used a piece of PVC pipe a few inches to raise the magnet above the fine. I centered then glued the "riser" to the fan and then glued a metal washer to the other end, which my magnet sticks to.

I use a hard drive magnet too and had a lot of trouble in the beginning with my stir bar getting thrown. It turns out that my magnet positioning was the culprit. I was centering the magnet on the washer thinking that a centered magnet meant my stir bar would be centered. I was just about to pitch my stir plate because it was so bad when it occurred to me that the stir bar may be catching on the magnet ends, if that makes sense. As soon as I positioned my magnet so that the ends were more towards the center, it all worked perfectly. No more thrown stir bar!



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[harebearva]

If you take 2 pairs of pliers and grab on to the metal at both ends, then bend the metal away from the magnet... it will pop right off. This is the first thing to do. The stir bar is magnetic too and may be attracted to the metal bracket as well and is getting "confused". Getting the RE magnet off of that bracket will let you get it just a bit closer to the stir bar. I tried using the small round RE magnets and no combination I found kept me from throwing the stir bar eventually. Once I used that big harddrive magnet, it worked flawlessly. It wont matter which side of the magnet is facing up, the opposing ends of the stir bar will have opposing magnetic fields... that's what makes them spin. You can also try gluing a steel washer on the fan and then sticking the magnet to that, it will allow you to adjust it if needed, but IMO, if it's pretty well centered, you're gold.