Electric stone mill
An affordable DIY electric matcha stone mill
Motorize a hand-cranked stone mill
Commercially designed electric stone mills are very expensive.
So here, I’ll explain the simple motorized setup that I use.
Items you will need:
1) A stone mill I made myself
2) An electric potter's wheel (a motorized turntable used in ceramics)
It should be able to switch between clockwise and counterclockwise rotation
3) A custom-made jig to prevent the upper millstone from rotating
Unlike typical electric stone mills, this setup rotates the lower millstone.
Typical electric stone mills are designed to rotate the upper millstone.
The problem with this design is that the handle of the upper millstone must be properly linked to the motor’s rotational motion, which makes the mechanism more complex.
Also, since the upper millstone is constantly rotating, there’s no easy way to add materials during operation.
As a result, a large hopper must be mounted on top of the upper millstone to supply the tea leaves.
Additionally, a large container must be placed beneath the lower millstone to catch the ground powder.
Things to consider when purchasing a specially designed electric stone mill
Commercial electric stone mills have several drawbacks:
They are very expensive, often costing several hundred thousand yen (this is the biggest issue)
They require a significant amount of space for installation
Some models require a 200V power supply
The quality of the built-in stone mill is often poor, despite being the most important component
After-sales support for the stone mill is unclear
Shipping costs from the manufacturer are high,
especially for overseas purchases, where customs clearance can also be an issue
For these reasons, I do not recommend electric stone mills from commercial manufacturers
A reversal of thinking
To avoid a complex structure, the lower millstone is rotated. An electric potter's wheel is used as the source of rotational power. A suitable mechanism is attached to prevent the upper millstone from rotating.
How to set up the device
1) Place the lower millstone at the center of the electric potter's wheel.
2) Try to position it as precisely in the center as possible.
3) Set the powder collection cup in place.
4) Place the upper millstone on top.
5) Secure the upper millstone using any suitable method to prevent it from rotating.
6) Add the material (tea leaves, etc.) through the hole in the upper millstone.
7) Set the rotation direction of the potter’s wheel to clockwise.
8) Start grinding slowly at a low speed.
9) Stop once to check how finely the powder is ground.
10) If everything looks good, continue grinding until you reach the desired amount.
If you want to grind it more finely
Do not add all the material at once when you start grinding.
Instead, add a small amount, let it rotate a few times, and then add a little more.
Since the upper millstone does not rotate, you can easily control the amount you add each time
You can grind not only tencha but all types of tea leaves
Recently, tencha has become difficult to obtain,
but you can also grind gyokuro leaves.
Matcha made from gyokuro also has a vibrant green color
