Gear: Stir Plate Build

January 4, 2012 by Jack
To make good beer consistently, one needs to have control over every controllable part of the process. I have been making yeast starters for every batch for a while now, but I didn’t have the best control over them. My process was to visit Jamil’s Yeast Pitching Rate Calculator, put in my OG, yeast manufacture date, set the starter type to “Intermittent Shaking,” and let it tell me how much starter wort to make. I’d combine the wort and the yeast in a gallon growler with foil over the lid and give it a swirl every time I walked by. This is a pretty good way to make a starter, but it’s not completely predictable and you can’t get perfectly repeatable results doing it this way. To achieve true consistency – or as close as you can really get – you need a stir plate.Commercial stir plates are expensive – ranging into the hundreds of dollars for the size I would need. Luckily homebrewers figured out long ago how to make one from some scavenged computer parts and a few items from Radio Shack.

I more or less followed the plans put forth by some guy named Dan in Michigan. (Thanks, Dan!) I tried to follow the instructions verbatim but it didn’t work well for me with my power supply and the parts I picked up. In the end I just went with a simple switch, potentiometer, and the fan.

The pot might burn out after some time because it’s not meant to run at full resistance non-stop. If it does, I’ll revisit the LM314 voltage regulator and see if I can get it to work. For now, though, it’s working great. Check out the whirlpool:

I have used the stir plate to make one starter so far: a 2L starter for a batch of 1.075 Foreign Extra Stout. My starters used to take about 48-60 hours to finish fermenting. On the stir plate it was done in 24 hours. More importantly, I was able to make a 2L starter whereas before I would have needed 3.33 liters! The stir plate will save me money in the long run, because starter wort isn’t cheap to make due to the high price of DME.

One Response to “Gear: Stir Plate Build”

  1. I just used Dan Jeska’s instruction as well. I’ve got the fan mounted and the wiring all done, and it’s working great so far! Now I’m just working on gluing the button neodymium magnets to the PVC spacer. It took me awhile to get the spacer just right, so that there was no wobble when I set it on the fan.

    Dan’s instructions are the best I’ve found. I actually emailed him, and he sent me a photo that helped me to understand how the components are hooked up. Without this photo, I would have been lost. If you want it, I can send it to you. I was successful with the voltage regulator and the other parts, though I have basically no understanding of how they work. Also, I haven’t heard anyone else talking about how the magnets can interfere with the operation of the fan if attached directly to it. It seems like Dan’s model just takes more into account, which makes sense as he actually sells these commercially through several outlets and has tons of experience making them.

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