TimEggers wrote:...split from Basket Overdosing; time for a serious re-evaluation! by moderator...Mr. Fox (or anyone else) how does this discussion pertain to triple baskets? I can see the point of a machine perhaps not being designed for 20g of coffee in a double basket, but how do triples pertain to this notion? Granted if a coffee is best at a 15g double, I doubt a 20g triple will be any better (as you note Mr. Fox). Tastes aside are triples taboo in regards to machine design/capability?
There are two issues here, Mr. Tim
The first issue has to do with the fact that some machines have trouble when operated without enough "headspace," e.g. when the ground coffee directly touches the group screen and in some cases this results in channeling or other gross extraction problems. In a case such as that, if you put the same amount of coffee into a larger basket, you might well avoid these specific, machine-specific problems since the ground coffee is no longer in contact with the group screen itself.
The second issue has to do with the quality of the extraction itself, assuming that this occurs without problems that might be machine dependent. Changing the amount of coffee put into the PF basket but running the same amount of pressurized water through it per given period of time, will change the extraction. The coffee will of course have to be ground finer if less is put into the basket and the same volume/time parameters are to be achieved. Different things will be extracted from a larger amount of coffee ground coarser, than will be extracted from a smaller amount ground finer.
There may be other things going on in particular instances having to do with the flow of the water through the PF and the coffee in it, that are changed by the geometry of the basket. I am not smart enough to figure out this sort of stuff, so you'll have to ask a whiz, someone who actually read his college physics textbook like Andy S. about that sort of thing. I just memorized enough of that physics stuff to give the appearance that I sorta understood it, but I really didn't.
As regards to the first issue, it is a matter of simple mechanics and not really the major point of what I have been addressing in my dosing posts. As to the 2nd issue, my expectation would be that by putting 18 or 20g into a triple basket, you are still going to get a sort of extraction that you will not get with a 14g dose, and these results are probably not going to be very much effected by the change in basket size.
ken