Machines

burrs again

Grinding coffee for non-espresso brewing at home is a pain in the tits. Short of finding space and the budget for a shop grinder your choices are limited and there a lots of concessions. When the Mahlkonig Vario arrived it was lauded as a grinder which could deliver a quality filter grind, and an espresso grind and sing and dance and do everything in between. Its performance grinding for brewed coffee left an awful lot to be desired.

For the past few months, however, on a daily basis I have been brewing filter coffee with a Mahlkonig Vario. The results have been excellent. The difference, notably is that the stock ceramic burrs have been replaced by a set of steel burrs designed specifically to produce a coarse grind.

What are the effects of swapping these burrs:

  • The grinder is rendered useless for espresso (one step from touching will produce a gusher).
  • The grind rate is greatly decreased (to about 1g/s at a filter setting – the old burrs do faster than that at an espresso setting).
  • The grinder is louder.
  • The noise coupled with the extended grinding time is a minor annoyance in a domestic setting, and perhaps a major annoyance in a light commercial setting.
  • The uniformity of the grind produced is comparable to some shop grinders.

This result suggests a few theories and questions.

Burr size is not necessarily the major determinant of grind uniformity. Perhaps small burrs are typically not good at filter grinding, because small burrs are typically not designed for filter grinding.

Why can some grinders not grind fine enough for espresso?

Is the speed reduction a factor in the output quality or a symptom? Does it suggest that the burr has to strike the coffee more times to achieve sufficient size reduction. Does this mean that the comminution is less explosive? … more controlled? Is there a relationship between burr size, grind rate and uniformity?

Even though the burrs are dramatically different looking, it is hard to elucidate the aspects of the burr desing responsible for these changes. The breaking teeth are shallower and there are many more of them. The cutting teeth are deeper and present a less angled face (they are closer to being on the radial axis). All edges are noticeably sharper to touch.

In any case, these burrs are not yet widely promoted, but they should be. Those in the business of selling Chemexes, Harios and the like to end users should want to offer these. The Vario is a solid grinder, and can with these make a very competent filter grinder. Even better perhaps would be a grinder using these burrs with fewer of the Vario’s bells and whistles, similar or better build quality and a somewhat lower price.

It would be nice if domestic grinder manufacturers defocused on espresso. Hopefully a critical mass of end users will emerge who understand the requirement for a better quality grind, to whom dusts and shards is unnaceptable. It requires enough users who don’t give a damn about espresso grind to create the market to drive these products.

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14 thoughts on “burrs again

  1. Kieran Gleeson says:

    I don’t suppose you tried leaving the bottom burr as ceramic and the top burr as the steel burr?
    If this produced a more palatable filter it may be a upgrade midground for people to use the Vario as an all in one unit.
    Just swap the top burr from ceramic to steel and back again as needed.
    I was very disappointed when I had my first cup of filter using the Vario, especially when my Solis 166 clone was producing fantastic filter, but I was very pleased with its espresso output.

  2. Interesting thoughts D… perhaps we should look to the SLR body for inspiration and the treat multiple burr-sets like the camera lens.

    As a retailer of the Vario, I would have certain concerns about consumers getting out their screwdrivers. That said, I’m sure the grinder manufacturers could come up with a simple bayonet-like system to minimise service issues… and given the potential revenue gain from offering multiple burr-set variations they may jump at the opportunity???

  3. I completely agree with your assessment, right down to the pain in the tits. These burrs may be my eagerly awaited dream come true.

    Can you share any more information specifically regarding performance compared to shop grinders?

    How can I get a set of these burrs? I could not find them on Baratza’s site or by searching for Ditting Vario burrs.

    Do these burrs require seasoning or are they finished from the factory such that they are ready to perform on the first use?

    Great post! Thank you for the information!
    Dennis Simpson

  4. Do you see any relationship then between burr speed and grind quality? I come from the metalcutting world and feeds/speeds/surface finish are closely related. I am sure that for a given burr shape there is an rpm that grinds smoothly, or as smoothly as can be hoped for given the interrupted cutting/crushing of coffee beans. No answers just thoughts I was having while reading this. Thanks!

  5. I’ve got a funny theory on grinding coffee, the finer you grind the closer you are going to get to uniformity in the grind size, simply because we are reducing the gap between the fines and the maximum particle size.

    Since coffee is quite brittle even top quality grinders will struggle to produce a uniform and course grind, this is easily visible by eye from the best grinder in class, a Tanzania.

    What we’re after is the most consistent particle size possible for the desired brewing method (even for espresso) then we’re most likely to get even extraction, then it is in the hands of the barista to get the best out of the coffee.

    Does this mean that with the grinder (unmodified) we’re discussing that a V60 will taste better than a clever coffee dripper? perhaps an aeropress will produce the best filter coffee. Or finer still is espresso or Turkish coffee the way to go…

  6. Terence says:

    Hi! Hopefully this comment finds you well.

    Just wondering, how did this stand up to the
    Maestro review you did a year ago? and which would you recommend for filters (not taking into consideration price)

  7. Nick says:

    Just FYI these burrs are offered via the Baratza website under parts for US readers, not sure on the foreign shipping policies of Baratza.

  8. Pingback: It’s All About The Grind | coffee corner

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