This isn’t meant to be so much a grinder review as an analysis of how the currently available crop of domestic grinders stack up against each other in a single aspect; grinding for espresso. This may sound a bit surprising, but I don’t intend to get involved in stuff like the presence or absence of static, dosers, timers or other features which vary from grinder to grinder.
What I AM interested in is the accuracy and repeatability of the grind produced, and how well suited it is to various types of espresso machines. There are some fairly simple physical principles at work in burr grinders. Grind quality depends on 3 main factors.
1) The surface area of the burrs. 2) The sharpness of the burrs. 3) The accuracy with which the gap between the burrs can be maintained during grinding.
Note that in domestic conical burr grinders the burr surface area each coffee bean is exposed to is large by comparison with flat burr grinders.
As a general rule, one grinder burr is held still (the STATOR) and one rotates (the ROTOR.) In most designs grind fineness is adjusted by moving the stator closer to the rotor. This is usually (but not always) accomplished by screwing up a threaded burr carrier, again usually the top burr. The quality and heft of this carrier and the accuracy with which the threads hold it in place determine the quality of the grind.
Barely a burr set, but cheap and common in low end grinders.
As with my recent evaluation of domestic espresso machines, I looked “under the skin” of various grinders, and found that there are at most half a dozen burr sets involved. So below is a summary of the ones easily available in Australia, although I’ve also mentioned USA models where I know the names.
Emide, Gaggia MM, Breville, Braun, Capresso (USA) La Pavoni PA (USA).
This particular burr set barely qualifies as a burr set. The actual burrs appear to be made from some sort of sintered metal, and there is nary a sharp edge in sight. Grind adjustment is performed by pushing the bottom burr, motor and all, up against the stator top burr, using a sort of wedge system rather than a threaded carrier. My frank opinion is that these grinders are totally unsuitable for quality espresso production.
Saeco 2002 burrs, note gaps.
Saeco 2002, G3 Ferrari.
A proper cast steel burr set on a threaded brass carrier, but the burrs are quite small and not as well designed as larger sets (note the gaps.) OK for short term use but they seem to wear fairly quickly. I've seen reports that the Saeco can't grind fine enough for the Silvia, but had no trouble on the second finest setting.
The Solis burr set, note the non-threaded top carrier.
All these grinders use the standard Solis conical burr set and all (except the Bodum, perhaps) are built by Solis. There is no doubt that this burr set is perfectly capable of producing excellent espresso grinds. Unfortunately the top burr carrier is NOT adjusted using a threaded system but by an inclined plane system. In my opinion this is less accurate as the top burr has more “play”, especially as the grinder wears over time. I have no hesitation in recommending the Solis 166 as a good matching grinder for most domestic espresso machines, but NOT for the Silvia.
Grinding fine enough for the Silvia pushes the 166 to the end of its range, potentially increasing the wear and reducing its lifespan, and I simply can’t recommend it as a long term match. Note that some of the models listed above cannot grind fine enough for espresso as manufactured, and need to be “tweaked” (internally adjusted) to get the correct fineness. You can find out how to do this at Ken Wilson’s UK website, http://www.kwilson.fsnet.co.uk/coffee_index.htm, as well as much other valuable info on grinders.
The Lux burr set, note the top carrier threads into the body of the grinder.
Lux, Innova Conical (USA), La Pavoni PB (USA), Iberital, Isomac and many others.
The one weakness of this burr set is that the threaded burr carrier is made from some sort of hard black plastic, however in practice this particular set seems to last as long and work as well as a brass carrier. The oldest model I have in the field is now 6 years old and still performing well, but will require new burrs sometime in the next year or so.
Certainly they can grind fine enough and accurately enough to produce excellent espresso on any machine, and do it consistently over a long period of use. I have had several queries concerning the availability of the Lux-type grinder in the USA, and I actually found it on this website, https://www.time-co.com/coffee%20store/index12.htm. Unfortunately it’s vastly overpriced (about 2 1/2 times what it should be, by my estimate)!
Rocky burrs, similar to many other pro burr sets.
Rancilio Rocky, Gaggia MDF, Mazzer Minis and so on.
These grinders use standard professional burr sets with professional brass threaded burr carriers, and, as you would expect, are fully capable of grinding for professional espresso machines. At this level of grinder (and price) other factors not related directly to the grind come into play, such as doser quality, speed, grind temperature etc.
There are a number of excellent grinder reviews on Coffeegeek and elsewhere, which (in my opinion) do a better job of addressing the “ergonomics” of the various grinder designs and brands than I ever could. As I said at the start, that’s not what I was trying to do, my interest is purely in the technical aspects of the burr types and how well they are capable of producing an espresso grind.