Three causes, and they compound each other.
Oily beans
Very dark roasts push oils to the surface. Those oils coat the burrs and the chute, and ground coffee sticks to them rather than falling through. Over weeks the residue accumulates and the passage narrows.
If you drink dark, oily beans, clean the grinder twice as often.
Static
Charged grounds cling to the chute walls and to each other. Fine grinding generates the most static, which is why espresso users see this more than filter users.
One spray of water on the beans before grinding — the Ross Droplet Technique — removes most of it.
Grinding too fine for the design
Some grinders have a chute that simply cannot pass espresso-fine coffee reliably. This is common on filter-oriented grinders being pushed into espresso territory.
Clearing and preventing
Unplug, remove the hopper, and brush the chute out. A chopstick or a soft brush reaches most of it.
Then: RDT before every grind, a bellows puff after, and monthly brushing.
When it is not clogging
If the grinder stops entirely and the motor strains, that is not clogging — it is a jam, often a stone. Unplug and clear it before running it again.
Last reviewed 8 August 2026