Grinder burr life is calculated in burr size and the amount of coffee put through each grounder. This is called the throughput. There are recommended grinder burr life spans, which will vary depending on several factors:
- shape of the burrs
- burr material
- size or cutting surface area of the burr itself
As a rule, small grinders use small burrs. The Mazzer Mini for instance, uses a flat burr set with a 58mm diameter. This cutting surface sees a lot less action than the Mazzer Major flat burr set, which measure 83mm in diameter.
Premature burr wear can be caused by debris that isn’t removed in the roasting and bagging process (i.e. small rocks, sticks, leaves, etc.). Motor shaft and/or bearing damage can also accelerate burr deterioration.
Signs of Worn Burrs
For serious baristas, you should start checking for signs that your burrs are needing replacement anywhere from 50-75% of the way through their recommended life (see chart below). Keep an eye out for the following signs that your burrs need replacing:
- the burr edges feel dulled
- the grinds are lacking consistency from grind-to-grind
- the espresso taste is flat regardless of other adjustments you make
How Can I Extend the Life of My Grinder Burrs?
To extend the life of your grinder burrs, you can keep them clean with a good grinder cleaner. This is the best way to lodge any solids and oils that can contribute to deterioration of your burrs. Removing, thoroughly cleaning, and re-installing burrs regularly also helps to extend the life of your burrs.
A Tip for Breaking-In New Burrs
When you get brand new burrs for your grinder, the burrs will need to be “seasoned”. You can season, or break-in your new burrs by saving a few kilos of old coffee and running it through your grinder. Mazzer Robur burrs are the most notorious for requiring this break-in period.