advice needed for this stir plate

[Hunky]

I built one based on plans seen somewhere that included the Radio Shack rheostat that is 25 ohm 3 watt. The slowest speed I can dial in with the rheostat makes the vortex reach the stir stick occasionally. I shot a video of it:
[ame="http://youtu.be/RKV4gqh5pWo"]http://youtu.be/RKV4gqh5pWo[/ame]

It could be that it is no problem but thought I would ask here. Also the stir stick is pretty noisy.. is that normal? Got it off amazon and it has hard edges that rattle against the glass bottom.

Oh, and the fan is 12v. and asks for 1000 mA, and my power supply is 12v 800mA.

thanks, JD

 

[prandlesc]

I think your stir plate looks great - nice cigar box! I've found that with mine, when I have yeast in suspension the liquid is thicker and the vortex doesn't reach the bottom as readily. As long as the stir bar isn't thrown off the magnet because it's spinning too fast, you should be OK. And my stir plate is a little noisy, too. Mine's in the basement so it doesn't bother me, but the rattling lets me know that everything is working.

 

[Hunky]

Thanks Prandlesc, I'll go with it then. I haven't secured the fan yet in the video or cleaned up the wiring, so that will all be a bit better than shown.

 

[Andrew_R]

Your stir bar has the ridge in the middle causing it to wobble.

They also make stir bars that are smooth down the full length which are much quieter.