Knife mill

A knife mill works like a grinder: a propeller turns very quickly and breaks the grain by beating. It has no milling adjustment; the longer you leave it, the finer it comes out. The result blends very fine dust with large pieces.

This mixture unevenly extracts: the dust is passed and bitter, and the large pieces are short and provide acidity. This is why they usually give flat or rough cups, especially in filter methods.

• In favor: very cheap and small.
• In favour: also for spices.
• Against: irregular and impossible to repeat milling.
• Against: Heat the coffee if you leave it too long.

They cost €15-40. If you use it, grind with short blows and shake in between. Better with a clear cover to see how it goes. Save it for Turkish coffee or an emergency.

The best improvement for little money is a manual grinder of teeth, from about 60 €. In the meantime, ask to get your coffee grilled for your method by buying it.