From the FAQs and Favorites:
Starting espresso setting for Rancilio Rocky and
How to find the Rocky true zero point.
It's nice to have a starting point provided by someone with the same setup, but it's even better to know how to dial in any grinder. Here's the trick I've mentioned a few times for dialing in a grinder: Grind a sample and pinch it between your fingers. It should feel much coarser than flour, but finer than salt. The grinds should stick together slightly; if the beans are fresh and the grounds don't adhere together, it's too coarse. If the grounds hold a fingerprint impression, it's too fine. If the coffee is fresh, you'll feel the moisture in the beans. If you don't, the grind setting is too coarse. Learning to judge the proper grind setting by feel will save you coffee, since the first extraction will already be in the ballpark.
Jim Schulman
offers similar advice years ago for grind settings from Turkish to French press:
another_jim wrote:Generally, a quick way to check grinds is to pinch them between your fingers and feel how granular they are:
- Turkish: a powder, like flour.
- Espresso: very fine grained, like 10x sugar
- Drip (fine grind): like fine sand
- Medium Grind (vacuum pots, fast French Press, and cupping): a tad finer than table salt
- Coarse (for slow french press): between table and kosher salt.
You can go to a supermarket, buy some cheap beans, and grind them at the standard setting to get a feel.
For espresso, the grounds should stick together when pinched between your fingers. If they don't, the coffee is either stale or the grind setting is too coarse. Although Jim describes the feel as "10x sugar", I would add that it should feel grainy when you rub it between your fingers. If you don't feel some grainy inconsistency, it's too fine.