Is single dose [without hopper] grinding inconsistent?

Beginner and pro baristas share tips and tricks.

Do you dose and then run the grinder until empty for each espresso?

Yes
87
66%
No
44
34%
 
Total votes: 131

Ken Fox

#1: Post by Ken Fox »

...split from Titan Grinder Project by moderator...



gscace wrote:The level of modding at this point seems a bit over the top. What are the boundary conditions imposed on the tests? Seems to me that the folks using them have little experience with them and are trying things willy nilly. I can tell you that both the Kony and the Robur like having some beans in the hopper. And the hopper fill switch is a non-issue for each grinder since there is a manual override.

Are we testing grinders, or are we testing modded grinders, or are we just modding grinders?

-Greg
This post from Greg Scace has long been buried in this thread, but deserves UNBURYING. I think that Greg made a very valid point and one that needs to be considered in this thread and in all its "derivatives."

It is one thing to mod one of these grinders and give descriptive commentary, yet another altogether to do what appears to be "controlled" testing on grinders that have been severely modded.

Most of these grinders are humongous, and it stands to reason that to whatever extent they will sell into the home market, that they will be modified. On the other hand, they were designed for high volume settings, and certain aspects of their design are potentially critical to their operations within "specs." For example, as Greg pointed out, these grinders are designed to operate with a bean load on top of the burrs, in the hopper.

Granted, you can remove the hoppers with various creative approaches, and attempt to provide the same effect by weighing down the beans entering the burrs with various weighted objects. Although this seems to be a valid simulation of the normal operating condition, is it really? Does this weighted object on top of the burrs simulate a full hopper for the last 5 or 10g of coffee that is being ground for a given shot? A mass of beans on top is going to fill all the gaps above the beans being ground and put fairly uniform pressure on those beans just entering the grinder burrs. A heavy weighted object is going to sit on top of the shaft on which the top burr is mounted and popcorning can occur beneath it in the gap between the heavy object and the burrs. If this was not true, the heavy object (a tamper, for example) would risk being chewed up as the last of the beans are being ground up.

This has particular relevance in what Jim is doing on his "can this beat the Robur" thread, where (I believe) more or less the exact weight of beans desired to be ground is put into the grinder and fully ground. A variable is being introduced that is not being controlled, e.g. the propensity of a given burr set to popcorn under the weighted object, even if it is only the last 5 grams or so of coffee that is effected.

In my own limited experience with my Compak K-10 WBC grinder, I have used mostly a small custom fabricated "mini-hopper" made of common plumbing parts

which nonetheless generally has at least 25 or 50 grams of coffee more than I am grinding above the coffee to be ground, then a weight on top of that. To the left, on the top of the adjacent grinder, is another white plastic plumbing part that I've planned to use for rapid coffee switches in the grinder, with a tamper on top of it. In my very limited use of this "micro-hopper" with a tamper on top of the beans, if I grind all the coffee out and use it, the pours have been inconsistent.

I applaud Jim's efforts in doing this testing and his efforts to find a way to use these grinders for "cupping" type rapid bean type switches. In fact, this was a major reason why I chose to buy the Compak grinder myself. I am coming around to the opinion that probably none of these grinders will function completely normally without at least a modest quantity of beans above what is to be ground for a given shot. Whether this quantity is 5, 10. or 25g, I do not know, but I do think it is NOT zero.

Another factor is that there are grinders that simply cannot be used without a bean load above the burrs; two prime examples from my own experience are the Cimbali Junior/Cadet and Max models. The popcorning that results in trying to use these grinders without a bean load on top has a very obvious, detrimental, effect on the grinds that vanishes as long as a couple of "layers" of beans are on top of those being ground during the grinding process. Because these grinders simply cannot be tested without some "excess" beans on top, is it valid (or fair) to comparison grinders to potentially "handicap" them by operating them without this bean load above the burrs? I think not.

I think it would be better to test these grinders with more than the exact quantity of beans to be ground for a shot above the burrs, if meaningful results that others can rely on, are to be obtained. Purchasing decisions by forum readers are another matter altogether, and this is where the reader has to determine if a great grinder, with all its design imperfections as relates to home use, is a good purchase afterall.

ken
What, me worry?

Alfred E. Neuman, 1955

User avatar
HB
Admin

#2: Post by HB »

Ken Fox wrote:I think it would be better to test these grinders with more than the exact quantity of beans to be ground for a shot above the burrs, if meaningful results that others can rely on, are to be obtained.
I agree. Although it wastes coffee, I always have a day's worth of beans in the hopper. Each session is preceded by purging the grinding chamber and then cleaning out the doser. I haven't bothered with single dose grinding in years.
Dan Kehn

DavidMLewis

#3: Post by DavidMLewis » replying to HB »

While I agree with Ken about the original design goals of these grinders, I'd like to see the sensitivity to bean load tested and mentioned. One of my prime desiderata in a home grinder is precisely this ability to switch easily among two or three different beans throughout the day, so I personally would like to know if a given grinder's design precludes it.

As an aside for those who have them, how does the Versalab, which is designed to be run empty, handle this? Is its augur given a reflex curve so that once a bean has entered it's pulled through or something?

Best,
David

Ken Fox

#4: Post by Ken Fox » replying to DavidMLewis »

Hi David,

How exactly do you propose that this be tested? All of these grinders are going to "popcorn" to at least some extent if you try to grind the last few grams of beans with nothing on top of them. How could you possibly test the importance of this observation? If in one grinder it is the last 5g that popcorns, and in another it is the last 15g, how could you establish this fact and what impact would shot dosing have on it (e.g. 5g popcorned out of a 20g dose is presumably going to have a different impact than 5g out of a 12 or 14g dose). How about the impact of a given espresso machine on the coffee with regards to the particle distribution from non-popcorned vs. popcorned grind percentages?

My opinion is that the only way one could possibly test this is with cupping and not with espresso. Is cupping done with coffee ground for espresso? I don't know, but it was my impression that it was not. I think that the results of any such evaluation are going to be so subjective that they will be useless. So then you would be left with basically someone's visual report on the amount of popcorning they see during the end of the grinding process, which in my view will be about as useful as "eyecupping," e.g. not very.

ken
What, me worry?

Alfred E. Neuman, 1955

User avatar
another_jim
Team HB

#5: Post by another_jim »

Four points:

1. If there is a half pound of beans weighing down every bean going into the grinder -- will that astronomical down force really prevent a bean from popping back out if it doesn't find a gap, and is instead smacked by the 500 to 1800 rpm rotating steel burr mounted to a half horsepower motor? Or will those added beans shorten the distance it travels and muffle the noise? Does popcorn covered by a blanket still pop?

2. Even if you clear out the 5 odd grams in the chute, you still have 3 grams or so in the grind chamber. If you leave the hopper off, you can clear that by pulsing the grinder after cleaning out the chute. If you use a hopper, you cannot, and have to sacrificial grind a second, then clear the doser, before each shot.

3. I did taste tests on this way back when I first got the mini, and Mark Prince dreamed up the popcorning problem (hopperless was pretty much SOP by 1/2 the people on alt.coffee those days.) I could detect no difference. Nor did I notice grind setting changes from a filled hopper to the setups I'm using for the Titan grinders. If the popcorn effect really exists, it should alter the way the grinder works, and there would be a change in setting. Also, the purported popcorn effect should lead to inconsistent pours from shot to shot. Ironically, the only two grinders that delivered inconsistent pours in this test were the Lux, where I kept the hopper filled, since it won't work otherwise, and the M3, which doesn't have a hopper. All of the grinders I "misused" have done just fine in terms of repeatable pours and taste. The last six test pours, using the big conicals I've turned on the two machines, waited 30 seconds, then turned off the two machines simultaneously, the pours are that easy to dial in. The tastes have been close to utterly identical too, and I'm groping for hairs, so I can score them differently. But I'm sure my pours would have been even more consistent if only I had filled those hoppers.

4. People have noticed one change with extreme popcorning, and I accept their observation. They say they need to grind finer. What does that prove? Popcorning shatters beans and creates more fines? Then it would require a coarser grind to offset the extra fines. Simple explanation: the grind is slowed down because the beans enter the burrs at a slowed rate. This means fewer grinds are going through the chute at any given time, and they are less compressed by the passage. When people dose by volume, the slower, fluffier grind will use less weight to take up that volume, and so will require a tighter grind. The effect will disappear if one weighs the doses. The same effect would magically appear if one has a full hopper, volume doses, and changes grind speed on a conventional doser-grinder setup.

As you can guess, I think the purported ill effects of popcorning are a myth. But prove me wrong if you can.
Jim Schulman

Ken Fox

#6: Post by Ken Fox »

another_jim wrote:Four points:


As you can guess, I think the purported ill effects of popcorning are a myth. But prove me wrong if you can.
Jim,

Theories and explanations are interesting, but in my opinion, not germane. If we really understood why these grinders act the way they do, then all we'd need to do is remove the burrs, do some measurements, photograph and measure the grind paths and dosers, then plug all our "data" into a mathematical equation and there'd be no need to even taste the shots . . . . .

You place me in an awkward position, that of trying to defend one of Mark Prince's "theories."

:mrgreen:

Given how "certain" he is about such things as freezing coffee, that is like asking me to explain how Chris Tacy's sensory apparatus can detect 0.1F temperature differences.

Nonetheless, you don't know and you can't possibly know how operating these grinders outside of their design parameters (e.g. without beans on top of those being ground) subtly effects the grind. What you do in your own daily practice is of concern only to you.

But, testers in the TGP are being asked to test these grinders because it simply is impossible to send these grinders around to all participants in these forums. Descriptions coming from you and others working on this project carry weight, because we are asking you to interpret this stuff that we don't have the opportunity to evaluate for ourselves.

If the grinders are being used in a way alien to the way that they were designed, the data "suffers" if by no other way than the perception that it might be tainted.

If the issue is that you don't have enough coffee to test these grinders with, I'm sure that Dan can arrange for a sponsor to send you some more for testing.

Best,

ken
What, me worry?

Alfred E. Neuman, 1955

User avatar
another_jim
Team HB

#7: Post by another_jim »

Ken Fox wrote:If the grinders are being used in a way alien to the way that they were designed, the data "suffers" if by no other way than the perception that it might be tainted.
Alien to the way they were designed?!? They were designed to stand in the bar of an Italian railroad station, grinding 12 Kg/Hr, running 45 seconds at a stretch to put 200 grams into the doser.

"Suffers" ? How about repeatedly flicking the doser to empty it-- doser vane whiplash syndrome, call the personal injury lawyers.

Just about everything in home barista-ing is alien to the design of the machines we use. But if my alienating the hoppers really makes people suspicious of my results, they are welcome to ignore them, and rely on the other half dozen people who will check out the Titans. In my opinion, if I had to do these tests in a way out of keeping with my SOP, they would have been less reliable, and I probably wouldn't have taken them on in any case.
Jim Schulman

DavidMLewis

#8: Post by DavidMLewis »

Ken Fox wrote:How exactly do you propose that this be tested?
Hi Ken,

I didn't mean to stir up a hornet's nest. The question for me is "can this grinder be used to grind one shot's worth at a time without compromising the taste of the resulting shot, and without wasting a lot of coffee when switching?" On this question, you and Greg seem to have one answer and Jim another, and since I respect the tasting and analytical abilities of all of you, I am at a loss to explain it. Hence my attempt to refine the question: the only explanation I can come up with is that you, Greg, and Jim aren't actually answering the same question.

Best,
David

Ken Fox

#9: Post by Ken Fox » replying to DavidMLewis »

David,

I think there are two issues here:

(1) the one you pose, to which I really don't have a well formulated answer,

and

(2) whether the answer to #1 should be assumed rather than tested, and if just assumed and not formally tested, is it appropriate to take the assumption and run with it, in the sense of "embedding it" into a test methodology that is supposed to be formally comparing grinders but might in fact be effected by extraneous factors such as how well a given grinder works without a hopper vs. another given grinder without a hopper.

It might be that some work well and others don't, but that if you used hoppers with some beans in them for testing, you would eliminate that question altogether and could just focus on the grinders.

ken
What, me worry?

Alfred E. Neuman, 1955

User avatar
another_jim
Team HB

#10: Post by another_jim »

David, I've done one after the other tests of hopper and no hopper with every grinder I get, including most of the TGP ones (I only did the little Macap, since the throat on the big one is the same). Grinding speed goes down, noise levels go up, but the grind setting and, as far as I can tell, the shot quality do not change. This is not an experiment, but just a quick test to find out if the grinder is suitable for doserless operation -- see my response to Ken.

Ken, you keep stressing the proper way to use these grinders. This is, to my mind, meaningless, or at least ambiguous.
-- Some people will buy these grinder for busy bars, keep the dosers filled, and be interesting how accurately the dosing adjustment, and how reliably the automatic refill, work. They may also want to know how well a "don't touch the grind setting" policy works over the course of a day. This may be the most proper way of testing the grinders, since that is what the engineers intended, and the market for which they are built.
-- For others, proper usage may be suitability for Barista championships and third wave coffee stores. In this case, the key will be how fast and accurately it dials in, how accurately a timer doses the coffee, how well the doser distributes the grinds into the basket, and how consistently the shots flow. Greg lives in this world, and that is what he wants to know. It is also an entirely proper set of issues
-- For others again, it may be about having one coffee grinder for the home of a coffee lover. It should be useful switching between three or four different coffees, and for espresso, drip and presspot brewing. This is my own need. More importantly, if someone were to ask me how adaptable a commercial grinder is for home use, this is the criterion I think is objectively the correct one to use for its ergonomics. By testing the grinders hopper-less, I'm addressing the questions of this category of user. I think that too is entirely proper.

I choose to test for the third kind of user, since that is who I am. If you think this is self-indulgent, you may be right. But I doubt I'd be of any greater use to the community testing these grinders in some way I don't intend to use them. My heart wouldn't be in it, and I'd be mailing it in.

In any case, I didn't see anyone falling over themselves volunteering to do definitive taste and accuracy tests on the auto-fill dosers :twisted:
Jim Schulman