Budget Stir Plate

[greenacarina]

Hello!

I am very much a tinkerer. I love to build stuff and fix stuff...household stuff, cars, electrical stuff, you name it.
Never used a stir plate for yeast starters before, but after seeing a number of examples on this site I knew this was definitely the way to go!!
Believe it or not I had EVERYTHING to do this project just lying around in various parts of the garage and the house.
I ordered a 2" stir bar and 2000ml flask from Ebay (about $25 total).
Had a small computer fan with 1" hub. Cut a 2" disc from a piece of scrap plexiglas, glued that onto the computer fan, then a couple of rare earth magnets onto the plexiglas (I have a bunch of these, rescued from old hard drives).
For my housing I used a Cool Whip tub. Drilled 4 holes to match the computer fan, mounted it on some 1" long machine screws with a compression spring on each one so I could adjust the height of the fan and the proximity of the magnets to the underside of the tub.
Had an AC adapter (wall wart) that is adjustable from 3v to 12v, soldered that onto the leads for my fan.
Put some dabs of silicone around the top of my tub, so my flask isn't sitting on the metal heads of the screws.
I can flip the tub over and store the AC adapter and wiring all inside when not in use.
I am pretty stoked to get to use this thing! I guess being a hoarder pays off sometimes. Lol!!

Chris

 

[cannman]

You might want to consider installing a fan-dial. I find my fan spins way too fast to catch the stir bar and ends up tossing it immediately. With the dial, you can make the grab, and then dial up the speed good luck!

 

[greenacarina]

I was hoping my adjustable wall wart might do the same thing.
At the 3v setting it's pretty dang slow. BUT...I am still waiting on my stir bar to arrive, so I may end up with the light dimmer inline.
I actually have one that I made up years ago....installed it in an outlet box, cut a short extension cord in half and wired it up to be a rheostat for whatever (dremel tool, etc...)
Very handy thing to have around!

Chris

 

[greenacarina]

Aaaaand a tip for those who may be attempting to make one of these....check your polarity on the magnets.
I found out the hard way that the stir bar is a magnet...not just a metal bar coated in plastic. If both the spinning magnets are the same polarity...no worky!
Live and learn!

Chris