Tuesday, June 7, 2011

DIY Stir Plate for 4$

OK so the 4$ may be an under estimate since I had most of this stuff lying around my house but for most Do-it-yourselfers they should have most of these things. My goal with this project was to build a stir plate out of crap I had lying around the house and with the exception of the potentiometer I did. If I had more than a $4 budget I would have done a lot of things differently. This is possibly the most white trash stir plate you are likely to find on the internet. If you find one please post it in the comments.

Step 1: Disassemble hard drive and retrieve rare earth magnet.
I had an old 120 GB hard drive lying around from an old computer I wasnt using so it got sacrificed for the stir plate. Take out basically every screw you can find on this the only thing your are trying to save is the rare earth magnets. Everything else is expendable and useless after taking apart the drive.

Once you have removed the magnet backing seen above take two pairs of pliers and bend the backing so that the magnet can be removed. There will be a thing layer of glue holding the magnet in place which is easily broken once the metal backing is bent. There will be one magnet on the top of the hard drive arm and one on the bottom, remove both.

Step 2: Wiring and construction
Now that all of that is completed here comes the fun part. You can really build this out of anything you want as long as the material between the fan/magnet and the surface is not metal. I used an old CD case spindle becasue it is round and a 2000 ml Erlenmeyer flask sits nicely on top.
Some double stick foam tape work great for attaching the magnet to the top of the fan and the fan to the base of the CD spindle I only had a 12 V power supply lying around so I used some resistors on the power line to lower the voltage. If you can find a 6 V supply these probably wont be necessary but I wouldn't go any lower than 6 V since these fans are meant to run on 12V. But what do I know I just threw resistors on until it seemed slow enough.
Once the fan is assembled to the base I cut a hole for the potentiometer on the top clear part and attached it. One small cut in the base of the clear top for the power cord and its ready to be assembled. The final project was actually pretty nice and self contained. The only problem I had was the top was clear so I could see all of the crappy wiring and tape holding everything together. Although it was clear so the SUPER COOL BLUE LED (vommit) fan got to show off with the clear case. The fan lights are actually pretty useful in case I can't find a flash light and need to see something poorly lit up within the 3 feet that the cord allows. Overall the stir plate works great for what it is and how much it cost. No, it doesn't create a gigantic vortex to the bottom of the flask but it will create a small one about 1-inch deep. Which is enough to stir the yeast and keep them healthy which is all I care about.

So the final cost of this project was 4$ for the 25-ohm potentiometer at Radio Shack. The goal of creating a functional stir plate for the least amount of money possible was achieved. Later I will probably build a better one but this was a quick 2-3 hour project to get me started. There was an additional cost of the stir bar of of ebay but I needed to buy that because I am not comfortable making something that is supposed to remain sanitized. The flask I had bought earlier becasue I was going to do starters but never got around to it. Now that I have my stir plate I will start.

1 comment:

  1. Any ideas on how I could make a stir plate that I could put in a oven? I have been baffled so far. I need it to be able to with stand 250 degrees F. Any help would be greatly appreciated. -Amy
    [email protected]


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