Grinder Burr Maintenance

THE OFFICIAL ANSWER:

The easy answer is to change your burrs based on the grinder burr manufacturer's recommendations. If you cannot find those

recommendations refer to the following guidelines below. 

 

Mazzer Mini (58mm flat)

Change at 300kg coffeee throughput

 

Mazzer Super Jolly (64mm flat)

Change at 400kg coffee throughput

 

Mazzer Major (83mm flat)

Change at 600kg coffee throughput

 

Mazzer Kony (63mm conical)

Change at 750kg coffee throughput

 

 

Mazzer Robur 110V (71mm conical)

Change at 770kg coffee throughput

 

 

Mazzer Robur 3 Phase 220V (83mm conical)

Change at 815kg coffee throughput

 

 

La Marzocco Swift (64mm ceramic flat)

Change at 1500kg coffee throughput

 

Burr life is calculated by factoring in burr size and the amount of coffee put through each grinder (“throughput”).  There are recommended grinder burr life spans, these will vary depending on several factors: whether the burrs are flat or conical, the burr material, and the size or cutting surface area of the burr itself.  Small grinders use small burrs; the Mazzer Mini, for instance, uses a flat burr set 58mm in diameter.  This cutting surface sees a lot less action than the Mazzer Major flat burr set which measures 83mm in diameter. 

Premature Wear

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 above).  Keep an eye out for the following signs that your burrs need replacing:

1)      The burr edges feel dulled.

2)      The grinds are lacking consistency from grind to grind.

3)      The espresso taste is flat regardless of the other changes you make.

How can I extend the life of my burrs?

Keeping them clean with a good grinder cleaner is the best way to lodge any solids and oils that increase deterioration of your burrs.  Removing, thoroughly cleaning and re-installing burrs regularly also helps.

A Tip for breaking-in new burrs

Saving a few kilos of old coffee can be useful to break in those new burrs, because new burrs ordinarily require a “seasoning” or breaking-in period.  Mazzer Robur burrs are the most notorious for requiring such a break in period.  

Ok, now how do I do it?

ALWAYS use caution and ALWAYS unplug your grinder before starting to work on it!

You will need two screwdrivers, and possibly and adjustable (crescent) wrench.

UNPLUG GRINDER and remove the bean hopper.  Make sure the gate at the neck of the hopper is closed!

1)      Push down the grind adjustment lock and unscrew the grinder burr carrier all the way out.  The direction will vary depending on the brand of grinder you are working on.  Some grinders do not have an adjustment lock, and simply rely on tension springs and a fixing screw to hold the grind adjustment collar. 

2)      There will be one burr on the bottom of the burr carrier you just removed, and one inside the grinding chamber attached to the motor shaft.   Each burr is held in place with two or three screws.  Using a flat head screwdriver, remove the screws from the burr that is attached to the upper burr carrier and remove the old burr – this is the easy one. 

3)      Removing the lower burr is a bit more complicated, as it is attached ot the motor shaft and will want to spin.  Using an additional screwdriver (or adjustable wrench on the fixing bolt), hold the lower burr carrier in place while releasing the burr attachment screws.

4)      Make sure that you remove any coffee residue from the mounting surfaces of the burrs.  Also clean all the adjustment threads in the burr carrier prior to installation.  This is good time to do a thorough cleaning of the entire burr area.

5)      After everything is thoroughly cleaned, install the new set of burrs.  Do not completely down each screw at one time, make sure to alternate.  Tighten each screw a little at a time until all three screws are tightened evenly.  This will ensure the burr is tightened down equally all the way around to prevent any unevenness. 

6)      Replace the burr carrier by simply screwing it back in.  CAUTION: It is extremely important that you use caution when reinstalling this part.  Do not force the carrier into place, as you can damage the adjustment thread (an expensive mistake).  If you place the carrier into position and thread it backwards, you should feel the collar drop into place and it will screw in much easier. 

7)      Once you have the collar in place and have screwed it in by a few turns, then you can plug the grinder back in.  With the bean hopper off and the power on, screw the collar all the way down until you hear the burrs barely touching, then turn back one full turn.  At this point your grinder should be ready to go, and you can begin to “fine tune” your grind. 

 

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