Hi Stephane,
Hopefully, we can get Matt or someone else interested enough to “science the s**t out of it”!
One of my questions is if i have an espresso grind, tamp it with 30+ lbs of pressure, and I can press through an espresso at 1:2 or 1:2.5 ratio at the 30second mark… then the flow rate is no different than a full espresso machine? If so, then the manual control could be used to explore prefusion/variable pressure questions throughout.
With the right grind and coffee, I can generate good crema with an espresso that is better than most 3rd wave cafes. If so, then think what someone who is a professional can do?
Btw, absolutely required is pouring water off the boil into the water chamber and releasing within 10 seconds to the coffee. Plus preheating the water chamber and portafilter if possible. I checked the temperature of the water chamber and anything else leaves the water temp too cold.
Anyway, I am waiting on my refurbishment kit for the Rok so can’t explore any further till then.,