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**Accidic** · 01-20-2012, 11:31 AM

Mass probably isn't your issue. If you manually turn it a couple revolutions will it take off? If so you may need a starter type circuit or that bigger ps to get it to work. Also keep in mind that stronger magnets can mess with the motors magnetic field which can prevent it from running. Metal washers can help to shield it from interference. The best one I've made had issues like that from super strong magnets and it took several to provide enough shielding for the fan to run correctly.

**tryn2brew** · 01-20-2012, 12:05 PM

Quote:

Originally Posted by Diaperload

I can get the fan to spin without the magnet glued to it but once I glue the magnet the fan won't spin when I turn it on. However if I give it a little nudge after I turn it on it will spin. How can I resolve this?

I cut a piece of wooden closet rod about 3/8" thick, and glued it between the magnet and fan, and it seems to work well.

**wfahey** · 01-20-2012, 05:45 PM

How in blazes did you get the magnets from the HDD apart? That is some serious pull!

ekjohns · 01-20-2012, 05:52 PM

Quote:

Originally Posted by wfahey

How in blazes did you get the magnets from the HDD apart? That is some serious pull!

most are actually glued on so get a regular screw driver and give them a whack

**Accidic** · 01-20-2012, 08:15 PM

If you're talking about from the frame most are screwed down even internally. HP scsi have a pinhole sized release that has a t7 screw inside.

If you mean from the back plate once you get them out, a tap on a screwdriver will work sometimes but be very VERY careful as it can hurt you badly. A safer approach is to use two vice grips on either side and bend the plate (not the magnet) and it is easily removable. Use a vice in place of one of the pliers if you don't have the strength to do it with pliers.

**mightynintendo** · 01-20-2012, 08:36 PM

Quote:

Originally Posted by wfahey

How in blazes did you get the magnets from the HDD apart? That is some serious pull!

You grab the metal plate the magnets are glued to on each end with a pair of pliers and then bend it back until the magnet pops off.

**mightynintendo** · 01-20-2012, 08:44 PM

Quote:

Originally Posted by Diaperload

I've been toying with my DIY stir plate for the past few days.

Here's some parts that I found or picked up at Radio Shack:

25ohm rheostat
(2) 80mm pc cooling fans
a couple DC switches. 1 is illuminated and 1 is not
3 magnets from old hard drives
a couple 1" stir bars
(1) 2" stir bar
2L Erlenmeyer flask
project box
(1) AC -> DC converter 6v

I can get the fan to spin without the magnet glued to it but once I glue the magnet the fan won't spin when I turn it on. However if I give it a little nudge after I turn it on it will spin. How can I resolve this?

On one of the fans I cut all the fins off to reduce mass. This helped a bit. Now the 'fan' will spin when I turn it on. It will also spin when I turn it on (with hd magnet glued to it). However, it won't spin when I turn it on and have the flask with spin bar in position. Sometimes I can turn it on and THEN place the flask on in. Takes about 20 tries to get the bar to spin though.

Has anybody else had these issues? What did you do to resolve this?

I have some ideas but they are just wild guesses.

Stronger fan with more torque?
Use a 9v converter?
play with spacing (add some rubber stoppers to the top of my stir plate)?

While it's fun trying to get this to work, it is getting very annoying.

I'm not an electrical engineer by any means, so if anybody has advice, please use language that would be understood by a 4 year old! Thanks.

yeah your fan isn't getting enough power. use a 9 or 12 volt power source.

HenryVance3 · 01-20-2012, 08:57 PM

You probably just need more volts to get it spinning

**E-Mursed** · 01-20-2012, 10:26 PM

Got mine built.....

Click on picture to view video.

Took two attempts due to a toasted fan and bad choice for charger.
I had to buy a 2 inch stir bar and it rattles a little bit when running.

Think I will notice any difference when my 1-1/2 inch stirbar gets here next week?

coypoo · 01-21-2012, 01:05 AM

Quote:

Originally Posted by E-Mursed

I had to buy a 2 inch stir bar and it rattles a little bit when running.

Think I will notice any difference when my 1-1/2 inch stirbar gets here next week?

Mine rattles pretty good too, and I can't figure our how to make it stop either. I just do it in the garage where no one can hear it.