Arduino Controlled Magnetic Stirrer




Introduction: Arduino Controlled Magnetic Stirrer

About: I'm a Qualified Electrician, with a love for designing and making things whenever I can.

Hi Guys & Girls. Here is my version of a 3D Printed "Super Slimline Magnetic Stirrer", created for the "Magnets contest". It has 3x speed settings, (Low, Medium & High) made from an old computer fan and controlled with an Arduino Nano.

Minimal materials have been used here, and so it's a pretty easy and cheap project to complete.

Use it in the kitchen to achieve those Perfect Throffy Coffee or Hot Chocolates :-)




Computer Fan (4-Pin)

4x M5 30mm Hex Bolts

Power Switch

3x 6mm Micro Switches

2x Magnets

Power Jack


3D Printer

Soldering Iron


Hot Glue Gun (Advised)

Step 1: Gather Your Materials

Step 2: 3D Printing Your Parts

Here are the 4 parts you will need to print. They have all been designed in TinkerCad with most walls being 1.2mm or 2.4mm, so be sure to set your hotend nozzle to print @ 0.6mm for a nice fast print time. Also I printed these with an Infill of 100% as they're mostly hollow prints anyway.

Step 3: Uploading Code to Arduino Nano

Okay, so here is the code used to control this project. Simply connect your nano, and compile the sketch.

Step 4: Soldering Your Circuit

So now we can start soldering our circuit into the main 3D Printed Shell. The best way to do this is to solder all cables to the switches, and power jack, leaving the Arduino until last. Hot glue is perfect to hold all components in place and also adds a layer of electrical insulation to all connections.

Once you have this done, take your fan and hot glue your magnets to the fan blades about 25mm apart, keeping them as centrally balanced as you can. Place your fan into the centre space and screw down tightly.

Next is to Solder everything to your arduino. Follow the wiring diagram in the photos, and then carefully push it into the space "to the left of the fan".

Step 5: Fan + Magnets

Okay, So here we have our PWM Fan. Normally a 4pin fan used to cool
your computers CPU. You will have 12v Positive, Ground, Tach (Tachometer, which will tell the computer how fast the fan is turning), and PWM/Signal wire. "Tach" wont be used here, and so we can cut it off. PWM is the one we want (Pulse Width Modulation). A quick google on your fan model and you should be able to work out what wires are for what. (PinOut Diagram)

This type of fan is perfect for our project as it uses a very small current to control the 12v fan. We can do this from our Arduino data pins. However, if we were to connect the fans 12v supply cable to one of these data pins on the Arduino, you will most likely fry the board. It will draw too much current (So please double check your fans wiring)!

So, as for magnets... Most magnets will do, but a nice strong "Neodymium" magnet is preferred. I made a spacer from corrugated cardboard to raise the magnets closer to the top on the unit. You may need to do the same, but for design purpose, I have left enough space so you can use slightly thicker magnets if you wish. Hot Glue or Super Glue should be fine...

Step 6: The Pill

Once you have printed both halves of your "Pill", you will see a 20mm x 8.5mm void as to which you can fill with any magnetic material you wish. Luckily I already had some 8mm threaded rod so I used that, but I was also considering cutting an old screwdriver or drill bit to use for this. Like I say, anything magnetic will do... (chopped Nails?)

Step 7: Assembly

Just about there now. Take your printed bottom plate, and press into the shell. It should snap in quite nicely.

You can then put your 4x M5 hex bolts into the feet, and screw them into the frame. And thats it ;-)

Step 8: Into the Kitchen

1.) Now, go into your kitchen and plug in your new device.

2.) Heat up 1 cup of milk in a microwave or over the hob until hot.

3.) Put 3 teaspoons of drinking chocolate in a Mug.

4.) Add 2 teaspoons of sugar.

5.) Add a tablespoon of milk and mix together.

6.) Pour half the heated milk into your Mug and turn your mixer onto "High"

7.) Add some pieces of chocolate.

8.) Slowly add the rest of your milk, turning down the speeds as you go.

9.) Add marshmellows, and top with a sprinkling of chocolate sprinkles, chocolate powder and squirty cream!

10.) Give this to your Mrs... Then, 5mins later you can ask her to help you clear up!!

Hope you enjoyed this project :-) Till next time

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    1 year ago

    Hi I have a question, What is the pill for?


    Reply 5 months ago

    The pill is used as the mixer. As the fan rotates, the magnets on the fan will cause the pill to rotate. If the pill is placed in a container, it will mix the liquid inside the container. I would be careful because if you 3D print the pill out of PLA, it can melt at high temperatures. I wouldn't use it inside a liquid you plan to drink, not sure how safe it is...


    Question 1 year ago on Step 8

    Hi, i have a silly question. Where do the magnets go ? Did you glue them on the rotor-blades ?


    Answer 1 year ago

    Hi Diagnostix84,
    I have added an additional step explaining how I did this.
    Good luck with the build ;-)


    Reply 1 year ago

    Aaaah, now even I have understood ;) Thanks a lot !