As part of my temporary housing setup, I paired the ROK Espresso with a Hario Skerton ceramic mill. The bottom container holds 100g of ground coffee, which is quite a bit. But, it could take half your day to grind that much.
The grinder element is quite small, and as a result, the output volume of each revolution is not much. If you are grinding fine for espresso, it will take at least a minute or two to grind enough. The other issue with the grinder is consistency…it’s not really. It’s only OK in this department. The saving grace here is that grinding fresh is so significantly better than pre-ground that the inconsistency does not really damage the cup much. But, I wouldn’t enter any competitions with this thing as my grinder.
Now, the real gripe. The adjustment mechanism is a massive pain in the ass. Adjusting for coarse grind is pretty simple, but getting fine enough for espresso is a monster effort. Trying to turn the adjustment thread with beans in the thing (as you should do when going finer to avoid damaging the burrs) will hurt your fingers. And, with no markings on the small cog you turn, it’s very difficult to adjust up, then back down to the same position again. So, lucky for me I only intend to use it for espresso and will not do large scale adjustments.