Coffee grinders that can grind for espresso

Espresso needs a grind fine enough to make a twenty-five second shot out of nine bars of pressure, and it needs to be adjustable in increments small enough that you can actually land on it. A grinder can reach the fineness and still be useless for espresso if its steps are too coarse.

The grinder matters more than the machine

This is the least popular true thing in coffee. A modest espresso machine with a good grinder makes better coffee than an expensive machine with a bad one, because the machine's job is to deliver hot water at pressure and the grinder's job is to control everything else. If you are choosing where to spend, spend here first.

Step size is what dialling in means

A shot that runs too fast needs a slightly finer grind, and slightly is doing real work in that sentence. If a grinder's next step down takes your shot from eighteen seconds to forty, there is no setting that gives you twenty-eight, and you will spend the rest of its life brewing around the problem. Stepless grinders remove the issue at the cost of repeatability; fine-stepped ones are the practical middle.

Burr geometry, not just burr size

Conical burrs are common, cheaper to make and forgiving. Flat burrs are more often chosen for espresso because they tend to produce a narrower spread of particle sizes, which shows up as a shot that tastes cleaner and repeats better. Neither is universally right, and a large well-made conical will beat a small cheap flat. What a maker publishes here is worth reading closely because it is one of the few places they publish anything real.

What to do about the rest

A grinder that holds its setting still needs beans it can work with. Espresso suits medium-dark roasts because they are more soluble and more forgiving under pressure, and lighter roasts are a discipline of their own. Espresso channeling covers what goes wrong in the basket once the grind is right.