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."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?
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.