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DIY Stir Plate Build
  • scoobscoob
    Posts: 16,617
    Here is my stir plate build I did a couple years ago...

    Stuff you will need:

    1) a project box, I used a 5x7x3 Radio shack plastic box or similar shaped box you have sitting around.

    2) a computer fan, snag as many from old computers as you can... dead useful for making things.

    3) 25 ohm 3 watt potentiometer, got mine from Radio shack when I picked up my project box, got a knob for it too.

    4) a single pole single throw switch to turn it on and off.

    5) power supply, 12v wall wort works pretty good, mine came from an old cordless drill charger.

    6) 3/4" PVC coupler, may need to be trimmed, I used a miter box to cut mine. The coupler is used as a spacer to raise the magnets away from the fan where they could cause interference in performance, and also to be able to set the airgap between the magnets and the box lid.

    7) 5 minute epoxy

    8) Mounting hardware for the fan, and adhesive rubber feet for the box to keep it from moving around when in use.

    9) Name tag magnet bar, it has two disk magnets in a plastic frame, if you have ever worked retail you likely have seen them.

    10) Erlenmeyer flask and a stirbar.

    The assembly:

    Place the computer fan in the center of the bottom of the project box and mark the hole locations to mount it, also mark locations on the front of the box for the switch and potentiometer, mark the back corner for the power cord to go through and also mark a few vent holes along the back of the box.

    Using a unibit or standard bit set drill your holes, the mounting holes are rather small, as is the hole for the power cord, the holes for the switch, pot, and vent holes are a good bit larger.

    mount the fan, the switch and pot, snip the end of the wall wort off so it can be fed through the small hole you drilled.

    With enough wire pulled through to reach the pot and switch, tie a knot in the power wire to keep it from pulling back through, I further secured my wire with a dab of hot glue.

    Before soldering any connections I would twist the wires in place to be sure it will work, attach the negitive lead of the power supply to one lug of the switch, attch the positive lead to the outside lug of the pot. connect the fan negitive lead to the other lug of the switch, and the positive lead to the center lug of the pot, plug in your power supply and check that everything works, the switch should kill the fan, and the pot should vary speed, from slowest or stopped at full counter clockwise, to full speed when full clockwise.

    If the pot works backwards, move the positive lead to the opposite side outer lug.

    With everything working properly, solder the wires to the lugs.

    Time to mount the magnets and coupler!

    Test fit the coupler on top of the center of the fan, and the magnet gizmo on top of that, check for a small air gap between the lid and magnets, I placed the lid across the box just to the magnets and found it would hit so I trimmed a tiny bit off the coupler with a miter box and hand saw, I set my clearance to about 1/16" below the lid.

    Now that everything is trimmed:

    Working fast, epoxy the coupler to the center of the fan using 5 minute epoxy, also epoxy the magnet thing to the top of the coupler, working fast I spun the fan a few times while adjusting the coupler to be centered on the fan, and centered the magnets across the top, with everything positioned correctly let the epoxy harden for a half hour or so.

    Screw the lid down and turn the stirplate back on to verify there is no contact issues, fill the flask with water, drop in the stirbar and center it on the stir plate and let er rip!!

    With everything working correctly you can now grow a huge starter or harvest the smallest dregs of yeast from your favorite craft beer!

    ***Here are pics of the assembly to clarify the steps above***


    thumb2_dscf1869-37471.jpg
    620 x 465 - 24K
    thumb2_dscf1860-37468.jpg
    620 x 465 - 29K
    thumb2_dscf1865-37469.jpg
    620 x 465 - 24K
    thumb2_dscf1866-37470.jpg
    620 x 465 - 25K
    thumb2_dscf1872-37472.jpg
    620 x 465 - 29K

    jlwThymceannt
    Jesus didn't wear pants
  • scoobscoob
    Posts: 16,617
    The last pic shows the pot full counter clockwise, I had to swap the wires so it would work opposite of how it was, aside from that small issue that was corrected, this stir plate has worked flawlessly for several years now...
    Jesus didn't wear pants
  • ThymThym
    Posts: 102,385
    that's fantastic... i love the saftey toggle switch, that's a nice touch.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • scoobscoob
    Posts: 16,617
    Lakewood said:

    that's fantastic... i love the saftey toggle switch, that's a nice touch.



    It was a nitrous oxide system arming switch I had sitting around, figured it looked damned sweet.
    Jesus didn't wear pants
  • ThymThym
    Posts: 102,385
    azscoob said:

    Lakewood said:

    that's fantastic... i love the saftey toggle switch, that's a nice touch.



    It was a nitrous oxide system arming switch I had sitting around, figured it looked damned sweet.


    they do look cool, and they just feel awesome to operate.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • C_BC_B
    Posts: 77,085
    Lakewood said:

    azscoob said:

    Lakewood said:

    that's fantastic... i love the saftey toggle switch, that's a nice touch.



    It was a nitrous oxide system arming switch I had sitting around, figured it looked damned sweet.


    they do look cool, and they just feel awesome to operate.

    This.
    "On it. I hate software." ~Cpt Snarklepants
  • ThymThym
    Posts: 102,385
    how much control over fan speed do you have with just using the pot for trimming?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • scoobscoob
    Posts: 16,617
    I can set it to hardly a spin, maybe 100 rpm, clear up to a full pulldown cyclone style spin seen in the last pic, I like to run it just fast enough to divot the surface, oxigenates great at that speed while keeping quiet overnight on the counter.

    with a full cyclone it churns air like mad, and you get a cavitation sound as the yeast volume grows and the starter gets thicker, it used to wake me up at night.
    Jesus didn't wear pants
  • ThymThym
    Posts: 102,385
    whats the electrical rating of the fan you used?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • scoobscoob
    Posts: 16,617
    The fan is rated at 1.2 watt, my power supply is a 12v 1.0 watt wall wort.
    Jesus didn't wear pants
  • jlwjlw
    Posts: 16,417
    Oh I'm building one of these.
  • jlwjlw
    Posts: 16,417
    Oh and very nice write up.
  • ceanntceannt
    Posts: 48,091
    Nice build thread
    In wine there is wisdom.
    In beer there is freedom.
    In water there is bacteria.
  • FuzzyFuzzy
    Posts: 46,600
    real nice. i've been putting this off for a long while.

    my only input: you can also snag some nice magnets from a dead hard drive, or a working one if hate it's face.
    "Oh, you were serious? I was drunk."-C_B
  • scoobscoob
    Posts: 16,617

    real nice. i've been putting this off for a long while.

    my only input: you can also snag some nice magnets from a dead hard drive, or a working one if hate it's face.



    Getting a curved hard drive magnet perfectly centered so the stirbar spins smoothly was my big concern in using one

    If it was off it might start spitting the stirbar at higher speeds.
    Jesus didn't wear pants
  • BenvarineBenvarine
    Posts: 1,606
    Just built mine tonight. I'll send pics when the stain dries and I get a stir bar on Friday. Thanks for the thread.
  • scoobscoob
    Posts: 16,617
    Benvarine said:

    Just built mine tonight. I'll send pics when the stain dries and I get a stir bar on Friday. Thanks for the thread.



    Anytime! glad to help, you use my plans or cherry pick some parts and freestyle it?
    Jesus didn't wear pants
  • BenvarineBenvarine
    Posts: 1,606
    I cherry picked the fan and magnet, bought potentiometer and switch from radio shack. Bought a box from Michaels art store for $3.99.
  • scoobscoob
    Posts: 16,617
    Benvarine said:

    I cherry picked the fan and magnet, bought potentiometer and switch from radio shack. Bought a box from Michaels art store for $3.99.



    I look forward to seeing the pics, you said stain and I was wondering what you had gotten off to!
    Jesus didn't wear pants
  • scoobscoob
    Posts: 16,617
    This stir plate build was a huge step for me in brewing, once I built it I was thinking, hell, I shoulda done this months ago!
    Jesus didn't wear pants
  • jlwjlw
    Posts: 16,417
    I have an old computer that I can get a fan out of. This I will go here soon and get the rest of the parts.
  • C_BC_B
    Posts: 77,085
    I really like the safety toggle switch. That is just friggin' sweet.
    "On it. I hate software." ~Cpt Snarklepants