From a few months back (for those who don't frequent Home-Barista) Interesting discussion on H-B here

 

First Post of discussion thread :
It's holy writ: espresso grinders need to be adjusted frequently and precisely. Holy writ is wrong; instead, you only need to adjust the grinder when you change the dose, the blend, or the style of shot (e.g. from ristretto to normale). All other grinder adjustments are a sign of sub-par technique.

How can this be? We all know that a grinder with too few grind settings will produce inconsistent shots, and we all know any cafe where grind adjustments are not allowed will have espresso that sucks. It turns out that frequent grinder adjustment is what economists and engineers call a 2nd best solution, something you do when the best solution is unavailable:


As the weather changes, as the coffee ages, as the static charges on the grinder wax and wane, the ground coffee becomes fluffier or less fluffy, and also more or less compressible.
These changes affect the density of the prepared puck.
So, if you dose by volume, it will vary the weight of coffee you use from shot to shot.
But the flow rate depends almost entirely on the weight of coffee.
So if you dose by volume, you will see frequent changes in the shot's flow, and have to make frequent grind adjustments.
Since these grind adjustments are retrospective and cannot anticipate how the ground coffee characteristics will change for the next shot; volume dosing will always be jittery, both in shot by shot flow rates, and in the compensating grind adjustments.

If you dose by weight, the jitters go away. Instead, the same dose from the same blend will always get you the same flow. Call this the principle of grind-weight invariance.

How do I know this? I first noticed it when I was doing the TGP. I could pencil in the grind settings on the grinders, come back to them four to five days later, and still be perfectly dialed in. You have to be more precise on the weight and the grind adjustment for smaller burrs or flats than for larger burrs or conical ones; but the principle of grind-weight invariance holds. Since then, for the past two years, I've been weighing doses. I've found, without exception, that when dosing by weight, once a blend is dialed in, it stays dialed in.

Consequently, I believe that the overwhelming reason for inconsistent shots in high end cafes is dosing by volume or grind time. Once they find a way to routinely dose by weight, the consistency of the shots will improve tremendously.
Jim Schulman

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Well Jim is highly respected for his knowledge, but everybody has their own opinion(s). I'm mobile in operation and the weather greatly affects extractions. Sometimes I can go days without making a single change in the grind setting, but there are days that I have to make a dozen changes before noon. Not subpar technique at all... call it humidity more than anything. I challenge him to prove otherwise.
Jim is correct on this one for the most part, but Shadow is right that a s%&!ltoad of humidity(I'm talking like full-on fog outside) will force you to adjust the grind setting a little bit.

Weighing your beans out, aka single dose grinding, really highlights Schulman's point imo. May not quite be the same case if you've got the hopper chock full to the brim at all times though...
Might I also point out the obvious that dosing by weight is really impractical in a shop setting... especially without a doserless grinder. Which is probably why this discussion was posted on HOME barista. But it does sound like a good idea. maybe future grinders will be able to weigh as they grind. that would be neat
Joshua Taves said:
maybe future grinders will be able to weigh as they grind. that would be neat

They already do. The higher-end doserless grinders come with some pretty trick features these days... but yeah Josh you're right in that they do grind a dose by timing rather than weight, but still it wouldn't be to hard to calculate out things that way.
If I owned my own shop I'd make sure there would be two 110v Robur-E's sitting on the counter. Whatever equipment money that's left over would go towards an espresso machine. ;)
The luxury of the "home barista" is that they can sit there, weigh and measure every single bean before doing anything. They're making coffee for themselves. They are not working in a professional environment where people are lining up for their drinks.

The "home barista" works in an idealized world that is in no way reflective of what we do on a daily basis.
Jeff Jaworski said:
Joshua Taves said:
maybe future grinders will be able to weigh as they grind. that would be neat

They already do. The higher-end doserless grinders come with some pretty trick features these days...

Really? What grinder actually weighs the dose?
I've followed this thread on HB with great interest without posting. The thing that I really like about some of the discussions over there is that, at their best, they are focused on making the best espresso possible. Nevermind practical considerations that may be relevant in production environments. They just want to make the best espresso that they can. Refreshing.

This is a home-barista oriented discussion for sure, though it does lead to some intriguing questions.

This really shouldn't come as a surprise to us either... we've known for a long time how important weight consistency is. Hasn't it been best-practice in our world to train until we can dose to hit a weight target with a high degree of repeatability? Mike, I believe you once recommended less than .5g variation, unless I'm thinking of someone else. Our dosing by volume or time is a compromise - necessary though it is. If someone could figure out how to make a durably quality grinder that did this, wouldn't you have one?

The humidity factor comes up in the discussion, but if you think about it this is kinda outside of their area of concern... not many there are pulling shots for hours outside. Come to think of it, not many of us are either.

Interesting discussion, glad it came over.
Brady said:
...Our dosing by volume or time is a compromise - necessary though it is. If someone could figure out how to make a durably quality grinder that did this, wouldn't you have one?

Hmmm... need to clarify that. I meant to say this:

If someone could figure out how to make a durably, quality grinder that did this dosed by weight, wouldn't you have one?

The "e" grinders and similar timer grinders don't dose by weight. They dose by time.

Sorry...
Took me about 20 seconds to come up with this...

A scale weighing the entire weight of the coffee (in the hopper and all) and maybe even the entire grinder, set to dispense however much you input (eg. 18g). Keep your portafilter off of anything being weighed (don't rest it on the forks).

So... lets say weight on scale is 20,418 grams (for some random number). You would want something tied in that would bring the total weight to 20,400 if you are shooting for a 18g dose.

That doesn't seem hard.

-bry
I dont think most kitchen scales are designed to hold a 40 pound grinder constantly. also, that much constant weight might take a tole on the grinders accuracy over time. and it would be really difficult also to dose every time without the portafilter touching the forks. especially with a line out the door...
Some say it can't be done. Others find a way and make it happen.

For those that like to poo-poo Home-Barista.com and some of it's regulars you'd best think again. Who do you think invented the Scace Thermofilter? And invented the espresso machine torture test used to certify competition machines including up to the WBC? Wasn't one of the "big boys", nope, a lowly "home barista". Who do you think had WORKING variable pre-infusion and full variable profile pressure control espresso machines BEFORE Slayer or Strada even prototyped? Again a Home Barista.

The technology readily exists to build a grinder that doses by weight. A grinder with virtually zero "throat grind hang". Coffee (and countless other comodities) packaging machines do much the same task everyday. It's a matter of either one of the "stuck in the grinder stone ages" manufacturers investing the R&D to make it happen or a new comer to the market. But it won't happen if there's not a perceived demand. Out of hand discounting the concept most certainly won't help make it happen.

Yes Brady, I've mentioned within .5g dose accuracy training. Timed grinding helps, but is a 2nd best solution. It is not as good (accurate) as a dose by weight grinder "could" be.
Mike-
It's not a matter of poo-poo-ing the HB guys, it's a matter of understanding the difference. When those guys discuss dosing by weight, you know that they mean it literally: busting out the gram scale, weighing the beans by hand and then putting them into the grinder to grind. They're not working a line of orders in a steady stream, dealing with the variances that happen on the line. In today's environment, under the pressure of the line, no professional barista has the time to weigh every dose of espresso. Right now it's an ideal and not our reality.

And for every Schulman, Scace and Schecter (starting to notice a trend here) there's a whole cadre of HBs that don't seem to understand the difference between making espresso at home and making it in a professional environment.

Certainly there are ways to achieve the ideals we desire. However, trying to convince the grinder manufacturers to produce is another thing altogether. Though, we have progressed over the years. The technology does exist to achieve dose by weight grinders, but the development and manufacturing commitment does not.

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