With the knowledge in mind, cocoa nibs when hot is a lot easier to grind. Cocoa butter which is solid at room temperature becomes liquid when heated. It readily flows out of the rotating burrs. Unlike the cold nibs, the burrs friction need to sufficiently heat the butter first before it flows out. This slows down the grinding and made the rotor harder to crank putting burden to motor (hands in case of manually operated grinder).
Gap adjustment. I made sure the mill was unplugged. I took out the hopper. Rotated the adjustment knob while manually rotating the rotor with a vice grip, until the rotor and stator surface touched it other. Then, rotated back the adjustment until I could turn the rotor freely without touching each other. Lastly, installed the hopper back.
About 400 grams nibs. Turned the machine on and slowly poured down the hot nibs. After few seconds, the liquid and finely ground cocoa liquor was pouring down nicely. It was a very nice development. The four times pass in my ordinary stone grinder and a DIY steel burr grinder were nothing compared to this.
The next problem was heat issue. The metal part becomes terribly hot to the point that it burns and boils the cocoa liquor. I should have supply the cooling feature with water from the start. This equipment has inlet and outlet for flowing water to fend off heat.
The six kilograms trial. I set up the next trial, but this time, I prepared six kilograms. I also bought a water pump to feed the cooling feature with water. The setup was, six kilograms cocoa nibs, colloid mill, water pump and a pail of water.
1. I setup the rotor / stator gap too tight. The cocoa solidify to the point that it could hardly get out. Widest possible setting of zero is enough to liquify the cocoa and get it out of the faucet. Careful fine tuning could be done while the machine is running.
2. One pail water was not enough as coolant, two were not either. I should install a large radiator with fan next time. A car radiator perhaps. Preparing a larger water reservoir should also be in my list. It is a nice precaution in case the radiator I selected has weak cooling capacity.
3. I got few scorches by monitoring the mill temperature with bare hand. A thermocouple or infrared heat sensor should be available next time.
Well, it was a nice learning experience. I am pretty sure I can master it very soon.