Stir Plate Build

[BARL Brewing]

After scavenging parts over time I finally started to assemble a stir plate. Now that it’s pretty much together I’m having a problem. The stir bar isn’t spinning; I guess that’s a huge problem....
Everything is working but the bar just starts to bounce around and doesn’t spin. I'm wondering if the magnet is the problem (harvested from a PC hard drive its a half moon shape), or maybe there isn’t enough space between the magnet and the bar.
Any suggestions?
Brian

[DrDually]

Mine did same thing...try this fix
Place stir bar in flask and tilt so it rolls to one side. Next place flask near drive magnet and let stir bar "couple" with magnets. It will then work properly

[Maynerd]

Also pay attention to the neg/pos charge on the magnet and the stir bar. My stir bar has one side attracted to a Neg charge and the other to a Pos charge. So on my plate build, I needed two magnets. Two magnets prevented my stir bar from bouncing around. It also helps to have the magnet centered properly. A high velocity spin with an off center magnet will cause the plate to shake. This could be adding to your issue.

[BARL Brewing]

Also pay attention to the neg/pos charge on the magnet and the stir bar.

I’m sure that’s it; I just haven’t gotten around to picking up some new magnets. Where would be an easy place to pick up some strong magnets, Frys?

Brian

[Maynerd]

I went to Radio Shack as a last resort (don't get the circular magnets). If anyone has a better place, please let me know because I am in the process of rebuilding mine.

[DrDually]

The only magnets that are strong enough are called "rare earth". The magnets you may find at electronics stores will not work as they are weak compared to rare earth types. If you have an old disk drive, and who does not, open it up and remove the magnets from read/write head. Be careful as they are brittle and will break easily. They can also pinch fingers. I used hot melt glue to attach them to the fan.

[floyd]

Hard drive magnets work great.. sounds like you just need to adjust the spacing a little.
I made one out of a computer fan with a 3 speed adjuster, a hard drive magnet, a small box and some duct tape and it works awesome..

[bwarbiany]

If folks need hard drive magnets, let me know. I'm pretty close to the source, so to speak.

[bwarbiany]

Magnets!

One of them is probably too small, but I think i've got 3 from 3.5" HDD's and 1 from a 2.5" HDD, Should cover the need for a few of you...

[BARL Brewing]

I only have one magnet and its about 1.5”. My stir bar is 2”. I guess that’s the issue.

[DrDually]

Break the magnet into two pieces and place about 2 inches apart in fan