You can use this hand stirrer to make foam in your cappuccino or macchiato coffee. Or simply as a mixer, fine powderer, etc.
- A metal wire, about 10 cm long and 1 or 2 mm in diameter, could be a big clip. It should be hard but moldable, and not too heavy.
- A small flexible spring.
- A motor (I took one from a broken CD player)
- A tube-like container with open caps in which the motor fits tightly. I used the plastic tube in which some pills come.
- A battery pack and some kind of push-button
- Wire, batteries, and tools
Step 1: Build Rotor, Motor, and Battery Pack
- BATTERY PACK:
Step 2: Put Parts Together
Now attach the rotor to the motor. Make sure they bind strongly and that the axis of the rotor and the motor make a continuous line (ie they don't make an angle). If this is not the case, then the axis of the rotor will precess in bigger and bigger circles, untill its bond to the motor will break.
As you can see in the photo, I used that kind of clay which hardens like metal.
Step 3: Make Foam!
Take the stirrer with your good hand (mine is the right one) and the battery pack / controller with the other. Introduce the stirrer in your coffee or whatever and make the motor run. In order to create a good foam, the spring must rotate in the interfase between liquid and air.
Make sure that you don't touch any hard object with the spring (like the walls of the cup or a spoon you may have) as this may bend / brake the stirrer.
...is produced when you have denatured proteins and/or lipids in your solution, since they make up the walls of the tiny bubbles. So normal hot milk in your cappuccino will be the best choice if you want foam on it.