Building a Stir Plate

Since we are graduating to 10 Gallon All Grain batches, we need to create yeast starters.  Otherwise the cost of yeast is crazy.  By creating a starter, we only need to purchase one package of yeast for most brews, instead of 2 or more.  To create a starter most efficiently, you need a stir plate.  This will stir the yeast, oxygenating it and propagating yeast growth.  A constant stir also knocks the carbon dioxide out of suspension.  Carbon dioxide is a by-product of yeast growth and also inhibits yeast growth.

Stir plates are expensive!  The least expensive one I could find was $50.  I can do better than that, I’ll build one!  There are plenty of tutorials online and It seems to be a very simple DIY project.

Start here at Home Brew

First step, gather parts.

The fan is an 80mm Case fan pulled from a dead PC
Power adapter is a 12v adapter I had laying around.  The fan is a 12v fan, so this is perfect.
I had a package of fender washers, so I used one from the package.

I purchased the rest.  First from Amazon:
4.7 x 4.7 x 2.2 project box – $8.44
10 Neodymium Magnets – $5.86
Zalman Fanmate 2 – $7.80
1 x 3/8 inch octagonal spin bar – $6.40

Then from The Home Depot:
8-32 x 2 inch Flat Head machine screw 4-pack – $1.18
8-32 Zinc plated nut 12-pack – $1.18

Total cost:   $30.78

The bag of screws also came with four nuts, but we needed 8 total for this project, making the bag of nuts necessary.

So, in opening the project box, we find the screws for the top.  The holes on the lid of the box are recessed.  The walls of the box are thick and solid.

I set the fan in the box, found where I wanted it and used a slender, long shaft Phillips head screwdriver to mark the holes for the fan.  I tapped the screwdriver with a hammer to ensure a mark I could see when I removed the fan.  I then drilled a 1/8 inch hole on all four marks.  Insert the screws from underneath and tighten a nut from above.  Screw four more nuts onto the screws to the approximate thickness of the fan. Place the fan on the screws.

Now that the fan is in place, move on to the wiring.  A Dremel tool makes quick work of the rectangular opening for the Fanmate wire harness.  Slide the connector out from inside.  Use your 1/8 drill bit to make the hole for the power adapter.  Cut the end off the adapter and pass the wires through the hole:

Connect the fan to the harness:

Connect the power adapter to the harness (remove the connector on the harness to do this).  Find the center of the fan hub and place the fender washer.   Place one drop of super glue in the center of the washer to test center placement.  Plug the power adapter in and observe the washer.  If it spins in a perfect circle, then add super glue to the outside of the washer.  If it does not then adjust and try again.  Once you are centered, place two of the magnets on opposite sides of the washer.  Remember to flip one so that opposite poles are facing up for each magnet.

Neat Wires are Happy Wires!

Put the lid on the box.  Find whichever vessel you will use for your starter.  In my case, I am using a 2000ml Erlenmeyer Flask.  Fill about halfway and drop in your spinbar.  You may have to move your vessel a bit until the spinbar “sets” itself by attracting the magnets on the fan.

Turn on your stirplate  and watch the funnel form!  The reason for the fan controller is to start the rotation slowly and turn it up so as not to throw the spinbar.

Now that the test run was successful, Open up the hole for the power jack.

Insert a DC Jack and solder the wires in place.The jack used here was part of the 10-pack I ordered for the Pump Controller box.

Here’s the vortex I get from the lowest setting:

And the highest setting:

This puts the total cost of the stirplate at $30.86, at least a $20 savings.  I can live with that.

The Flask can be found here:

While stirring, I will be using a 3-piece airlock and a drilled rubber stopper from a Better Bottle which fits this flask perfectly and I had lying around.  If you need one, you can use a #10 stopper.

Brew Happy

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