Homemade Yeast Stir Plate

[der wo]

It's about the exact construction I made for my magnetic stirrer.

Form follows function. If you have similar parts, then there is only one way to assemble them.

[Fart Vader]

To anybody having issues with DIY stir plates throwing magnets. I have the solution for you.

Like probably a few of you, I googled how to make one of these using a PC fan and magnets. Sounds simple enough.
I have a bunch of fans. I bought some rare earth magnets. glued them to the fan. Too easy. WRONG.
No matter what I tried, my stirrer just kept throwing magnets at low speed.
Ok, let's try scavenged hard drive magnets.
Same problem. WTF???

I left this project alone for a couple of months then I think I had a eureka moment.

Step 1. Find a steel washer, I doubt the size matters.
Step 2. Power up the fan on low speed (much easier if you have a variable power supply) until you are sure the washer is centered.
Step 3. Once centered, use hot melt glue or epoxy and glue the washer to the fan.
Step 4. Wait until the glue/epoxy has set (I learned the hard way).
Step 5. Place your magnet on the washer, trying to center it as best you can. I didn't try with the single rare earth magnets I bought because I had already cannibalised hard drive magnets.
Step 6. Put your container with water and the stir magnet on top and see how she runs.
Step 6a. Stop and move the magnet around if you still throw the stir bar.

Single fan close up

For my purposes, a piece of plexiglass was the perfect "cover" for my fans and magnets.
I need to produce 6L of yeast colonies for my batches.
This works perfectly with 6x 1L mason jars.

Six stirrers

I used hot melt to attach the fans to the plexiglass.

Once the magnets are aligned correctly (which seems to be critical), I can crank the power up without throwing magnets.
I have 12v fans, and cranked the voltage up to 16v !!! No idea what the RPMs are, but the cyclones were impressive.

Cyclone

I hope this helps somebody.
I know I was about to give up.

Cheers.

P.S. If using scavenged hard drive magnets, you'll probably have to use box cutter blades to separate the magnet from the washer. I know I did.

[Brutal]

@FV, so it looks like you cut holes in the plexiglass so the washer and magnet are closer to the Mason jar. That sounds simpler than building stands to hold it away and being closer should work better anyway. Very nice buddy! With the bottom of the jar being somewhat thick and slightly convex that seems like a perfect solution.

[Fart Vader]

Right on the money Brutal.
I thought it worked out very well.

[jdetechguy]

To anybody having issues with DIY stir plates throwing magnets. I have the solution for you.

Like probably a few of you, I googled how to make one of these using a PC fan and magnets. Sounds simple enough.
I have a bunch of fans. I bought some rare earth magnets. glued them to the fan. Too easy. WRONG.
No matter what I tried, my stirrer just kept throwing magnets at low speed.
Ok, let's try scavenged hard drive magnets.
Same problem. WTF???

I left this project alone for a couple of months then I think I had a eureka moment.

Step 1. Find a steel washer, I doubt the size matters.
Step 2. Power up the fan on low speed (much easier if you have a variable power supply) until you are sure the washer is centered.
Step 3. Once centered, use hot melt glue or epoxy and glue the washer to the fan.
Step 4. Wait until the glue/epoxy has set (I learned the hard way).
Step 5. Place your magnet on the washer, trying to center it as best you can. I didn't try with the single rare earth magnets I bought because I had already cannibalised hard drive magnets.
Step 6. Put your container with water and the stir magnet on top and see how she runs.
Step 6a. Stop and move the magnet around if you still throw the stir bar.

SingleFan.jpg

For my purposes, a piece of plexiglass was the perfect "cover" for my fans and magnets.
I need to produce 6L of yeast colonies for my batches.
This works perfectly with 6x 1L mason jars.

SixPlates.jpg

I used hot melt to attach the fans to the plexiglass.

Once the magnets are aligned correctly (which seems to be critical), I can crank the power up without throwing magnets.
I have 12v fans, and cranked the voltage up to 16v !!! No idea what the RPMs are, but the cyclones were impressive.

Cyclone.jpg

I hope this helps somebody.
I know I was about to give up.

Cheers.

P.S. If using scavenged hard drive magnets, you'll probably have to use box cutter blades to separate the magnet from the washer. I know I did.

Beautiful work of art here.


Sent from my iPad using Tapatalk

[greenacarina]

I will have to post pics of mine when i get home.
Other than the flask and stir bar (ebay) i used stuff i had lying around.
Computer fan, hard drive magnet, variable voltage wall wart, cool whip tub, epoxy, silicone and some machine screws.
It's a little ghetto, but it has character...and it works!

Chris