Rolling Stir Bar

[Ghoti444]

I just completed my homemade stir-plate. Everything works great except for the stir bar. The stir bar rolls, it does not spin with the magnet. The magnet is from an old hard drive. It is on top of a ¼” spacer, which sits on the computer fan. Any ideas how to get the stir bar to spin?

 

[Jaybird]

Are your magnets (2 of them) + up on one side and - up on the other? If not flip one of the magnets. How far away from each other are the magnets? Too far away and the stir bar will attach to 1 of the magnets but no the other.
Jay

 

[Ghoti444]

Unfortunately I only have one magnet.

 

[Clementine]

Do you have variable speed control. Some times the fan is spinning too fast and the magnet gets out of sync with the motor. I have to start my on low and speed it up as the fluid in the E flash gets going.

Clem

 

[maida7]

fan speed and the distance from the fan are the 2 key factors in getting the bar to spin without throwing it. I play with the speed control and use books to change the gap between the magnet and the flask until i find the magic combination. Such is life with a homemade stirplate. I expect the expensive lab quality ones don't have these issues.

 

[XxonValdez]

Unfortunately I only have one magnet.

That is likely the problem.


In the lab they still throw the stir bars as well if you start them to fast.