The grinder produces clumps

Ground coffee comes out in visible lumps rather than as loose grounds, particularly at espresso settings.

Applies to: Espresso machine, Espresso

Likely causes and adjustments

Try one adjustment at a time so you know what actually changed the result. Start with the first cause below — if it doesn't help, reveal the next.

Cause 1 of 3 · Commonly the cause
Normal behaviour at fine settings
Almost every grinder clumps at espresso fineness. Stirring the dose with fine needles before tamping deals with it.

Step-by-step guides to the skills this problem comes from.

Distributing espresso grounds (WDT)Leave the coffee bed uniformly dense throughout, so water meets the same resistance everywhere and does not carve a channel.