@@MeilingZhao Interesting idea! It's possible that a conical burr grinder may work better than a flat burr grinder if you can push the cacao down into the burrs. It may be quite hard to clean between uses though.

Please yes! I want it too

@@singhrustam dont try to wait man, he doesn not respond

It's a super fun and rewarding project! I think my biggest mistake in a design sense was making poor assumptions about the torque relationship between smaller and larger burrs. It's clearly not a linear relationship based on burr radius. I think it depends much more on the specific geometry between the inner and outer burrs as each bean is crushed, something that's very hard to model or calculate. If I were to do it over, I'd make a simple 3d printed setup with the big burrs a hand crank to measure the torque, then spec a motor based on that info. Windshield wiper motors should have enough torque when paired with a gear/pulley system but they also don't provide torque info so you'd need to measure the motor torque. Hope this helps.

Hey there, I have not done any fancy measurement of grounds sizing, but espresso shots with my Breville machine have been very consistent