Burrs (coffee grinder)
Burrs are the cutting elements inside a coffee grinder that fracture beans into particles. Two types: flat burrs (two horizontal discs, high uniformity, bright flavor) and conical burrs (angled cone inside ring, lower speed, less heat, sweeter cup). Burr diameter matters: larger burrs (64 mm+ flat, 40 mm+ conical) produce more even particle distribution. Material: stainless steel (standard), titanium-coated (extended life), ceramic (home use, lower durability). Replacing worn burrs is critical for extraction consistency.
Background & Context
Meules (burrs in English) are the grinding surfaces at the heart of every burr coffee grinder — two abrasive discs or cones that fracture coffee beans into particles by combination of cutting and pressure. The term comes directly from the French word for millstones, reflecting the ancient lineage of the burr grinding principle. In specialty coffee, burr geometry, material, and alignment are the primary determinants of grind quality — more so than motor speed or grinder brand. Flat burrs (two parallel discs rotating against each other) produce a bimodal particle size distribution — a primary peak of coarsely cut particles and a secondary peak of "fines" — associated with flavour clarity and distinct taste separation. Conical burrs (a cone rotating inside a ring) produce a more even, unimodal distribution associated with body and sweetness. Burr materials: stainless steel is standard; titanium-coated steel increases hardness and longevity; ceramic burrs are used in hand grinders for their low friction and heat generation.
Practical Use
For practical burr maintenance and selection: burrs have a rated lifespan (commercial flat burrs: 500–1,000 kg; conical burrs: 1,000–1,500 kg) after which they become rounded and produce inconsistent particle sizes. Visual inspection (looking for worn ridges) and taste evaluation (shots becoming harder to dial in despite unchanged parameters) are the primary indicators of burr wear. Burr alignment — physical parallelism of the two grinding surfaces — is more important than burr material: misaligned burrs, regardless of material or geometry, produce wider particle distributions and inconsistent extraction. Many specialty coffee enthusiasts ("alignment nerds") spend significant time shimming and adjusting their home grinders to improve burr parallel alignment as the highest-return performance upgrade available.
Related Terms
Related terms: Coffee grinder, Burrs, Grind size, Espresso extraction, Extraction yield.