The problem with grinders

December 30th, 2009

A small part of the coffee industry moans quite a lot about coffee grinders, especially espresso grinders.  I confess I am one of those people, and I thought I’d post a little bit about what makes us so grumpy but also look at why nothing has happened.

These are coffee grinders from the 50s (photo by yellow_speedster):

This is a coffee grinder available in 2009:

I went with a Faema grinder here because I think the ones above are Faema too.

So – in 50+ years what has changed?  The cheeky answer would likely be that coffee grinders have gotten less beautiful, but that is besides the point.  There has been virtually no evolution.  A bean hopper above horiztonal burrs, feeding the ground coffee sideways into a dosing chamber.

Why haven’t coffee grinders evolved?  Because they don’t need to.  For a long time there was very little innovation in espresso machines too 1. I’ve probably mentioned before (ad nauseum) how Italy is pretty happy with espresso, and for a long time had little drive to improve it – I say this as a good thing in many ways, espresso in Italy is a lot better (on average) than anywhere else.

Just about everywhere espresso spread, Italian technique spread too: 6-7g doses, delivered from a dosing chamber with a goodly amount of coffee in it, ground that day.  Coffee grinders haven’t evolved because the vast, vast majority of technique hasn’t needed them too.

As well as being a moaner I hope I am a realist.  The size of the speciality coffee community, in terms of % of grinders bought annually, is very small. Just think of the ratio of good cafes to bad in your local area.  What we want would demand a healthy spend on R&D that would likely take a long time for the manufacturers to recoup due to limited sales of high end grinders.

With espresso machines I think there have been a few key differences that sped up evolution – one of which is the home user community, brought together by the internet.  There were probably more PIDs on home espresso machines globally than commercial ones for a little while – though someone from the alt.coffee days could probably give a more accurate timeline.  The R&D work, the beta-testing, to some extent was already done.  People were measuring and reporting the effects on shot temp stability and in only a very few years this technology has become a part of at least one of every manufacturers range of espresso machines.

Perhaps the home enthusiasts will create the breakthrough in grinders.  It really wouldn’t surprise me, going to be conversation already going on online.  So what do people want?  Interestingly a lot of what commercial operations want from a grinder, home baristas want from a grinder – despite the very different applications.

Grinding to order – without clumps

Grinding to order has two advantages:  firstly the coffee is fresh, secondly there is minimal waste.  To achieve this we are mostly using standard doser or doserless grinders with digital timers – either factory fitted, or hacked in afterwards.  No one really wants to use a dosing chamber – there is something quite silly about the extraordinary number of dosing pulls that a busy day requires, but we don’t want clumps.  Most grind on demand grinders produce clumps of grounds that don’t really help the even extraction of coffee.  The Mazzer Robur is better than most, but still not perfect.  The doser at least breaks up these clumps.

Annoyingly most of these clumps are created because even doserless grinders are based on doser grinders, and therefore have horizontal burrsets.  To get the coffee from the burrs to the portafilter it passes through a little tunnel and in that journey gets somewhat compacted causing clumps.  Not all grinders have horizontal burrs – a number of shop grinders have vertical burrsets.  The Simonelli Mythos grinder was interesting to me because it has angled burrs, fed by an auger.  However, the coffee still travels through a little tunnel on the way to the portafilter so clumping remained an issue.

The only espresso grinder that I’ve seen that doesn’t do the little tunnel thing is the Disco Volante grinder, made by La Marzocco some years ago, that has a dosing chamber all around the burrset.  A wonderful idea (photo by Mark Prince):

Cool running

A big problem with grinders in high volume locations was the build up of heat.  Adding fans to the casings of grinders has been going on a while, though in my opinion it doesn’t really address the source of heat.  Most fans remove heat generated by the motors, and no doubt the do generate some heat.  The most damaging heat is in the burr chamber.  Espresso brewed from grounds that were heated dramatically as they were ground doesn’t taste as good as coffee that was ground at a lower temperature. 2

The biggest problem, when it comes to heat build up in the burrs, is coffee itself – specifically ground coffee.  Ground coffee does a superb job of insulating the burrs, meaning they get hotter quicker.  In an ideal world the burrs would grind until completely clear of coffee on each usage, which would significantly decrease the rate at which the grinder gets hot.  This is a problem – because that would mean measurement of the coffee before it is ground, something a timer could not do.  This is one problem that I hope someone comes up with an elegant solution for.  We could actively cool the burr chamber, but it would be tricky to cool the burrs themselves.

Just about every advancement in coffee grinders has been about trying to improve that basic model of grinder that we saw from the 50s. What if we just started again, what if we wrote a simple list of things we want a machine to be able to do and created a machine designed to only do that.  On my list would be the following:

- To finely grind a controlled portion of coffee quickly and repeatedly

- To retain no ground coffee

- To give accurate control over the size of the portion and the size of the grinds

- To prevent build up of heat around the coffee

I like a simple list, it feels more achievable.  Do we need it to do any more than that?  I’d love to hear your thoughts in the comments.

Should any manufacturers be reading this – I will happily donate a good number of hours of my time to work in any way helpful if you want to build something like this.  Just drop me a line.

  1. beyond inventive ways to stop customers cheating on coffee agreements with free-loan machines!  ↩︎
  2. This is an observational opinion – I would welcome argument, clarification and more discussion  ↩︎

Comment Policy

There are no longer comments on new posts. If you'd like to respond you can find me on twitter.