Yes, I stand corrected by the same fairy godmother.

I really don't get the hooplah over a zero retention - I've worked in scores of cafes and am now happily brewing coffee at home. Get an EK, properly align it, dial it in, and if you have .05 gram difference, so what? What tolerance are you working with on the water end? Can you truly stop your shot at your desired weight every. single. time? I'd wager no. An EK won't lose value, it's virtually zero retention, and, in my opinion (which all of this is, right? taste is subjective?) it produces a magnificent shot, provided the barista knows what s/he is doing. Someone mentioned that we're in the golden age of espresso - I agree. There are loads of great grinders out there. Just get a good piece of equipment and be done with it! I understand that an HG1 may no longer be viable and you need to change, but a monolith flat max is not the end all, be all either.

The issue about retention in a home grinder is that it can be several grams, left getting stale in the grinder til you make your first shot the next day or even several days later. It's not that the retained grounds are "lost", but rather that they make the next day's first shot taste bad.

That isn't an issue in a cafe since after you make one shot, you usually make the next one a few minutes later at most, before the retained grounds have really gone stale. And the first few shots the next day are done as dial-in rather than served to customers.

So designers of commercial grinders (intended for cafes) have usually not cared about retention. They even have dosers holding enough grounds for multiple shots. As long as it is used quickly, it is fine. But home grinders face an additional constraint that there can be a much longer time between shots. Therefore it helps for them to be designed to have low retention.

purging=wasted beans

The retention issue is discussed very well in DaveC's Niche Zero review, pages 5 - 7. He discusses retention in terms of total retention, dose consistency, and exchange. He measures the Niche, comparing it to what he finds in other grinders and writes that its retention, resulting in any exchange of old grounds for new, is too small to taste.

ira wrote:Except for the burrs and the tolerance in the threads, the Monolith is inherently perfectly aligned. It's the same basic design as most of the Mazzers and all the other big top fed grinders. The difference with the Monolith is Dennis tries very hard to assure perfection. Grinders like HG-1s and Versalabs require alignment and can get out of alignment.

Ira

Versalab M3s (last couple of years) and M4s do not get out of alignment.

voozy wrote:The issue about retention in a home grinder is that it can be several grams, left getting stale in the grinder til you make your first shot the next day or even several days later. It's not that the retained grounds are "lost", but rather that they make the next day's first shot taste bad.

That isn't an issue in a cafe since after you make one shot, you usually make the next one a few minutes later at most, before the retained grounds have really gone stale. And the first few shots the next day are done as dial-in rather than served to customers.

So designers of commercial grinders (intended for cafes) have usually not cared about retention. They even have dosers holding enough grounds for multiple shots. As long as it is used quickly, it is fine. But home grinders face an additional constraint that there can be a much longer time between shots. Therefore it helps for them to be designed to have low retention.

I don't see why there is anything left at the end of a session anyway. When I'm done grinding for the morning I use a brush and swipe the burrs, then use it to swipe any grounds left in the chute (leading to doser) then give the doser a quick swipe. I always use this bit for my last double so there is virtually nothing wasted/left to stale. Once I finish the brushing I use a handheld vac to touch up those areas of what tiny bit of residue there is and I have a fresh/like-new grinder for the next morning. All said and done it takes maybe 1 minute.

I could not agree more. The late M3s and now the M4s are constructed in such a manner that all but the lateral alignment is fixed - interference press fits and such. The lateral alignment is automatically very close, being pinned to hold within .004". With the burrs we use, anything closer than that is very immaterial.