another_jim wrote: Both the Cimbali and Elektra are a lot bitchier on dose than the E61s, LMs or Synessos (don't know about the new NS or LS or DC). This explains why Ken and us Elektra owners are more skeptical about updosing.
Actually, this is not my experience with Cimbali Juniors (I have no experience with their multigroup machines, nor with any of their Bistro models).
For a number of years my standard dosing was to fill the basket with a mound on top, sweep off the excess, then tamp like hell and pull the shot. With my vibe machine, although I got occasional channeling, most shots were fine. I have weighed the basket contents a number of time with this approach, and the average weight was about 19g.
When I bought the "new" rotary (now 4+ years old) I put the vibe machine down in the basement, but continued dosing and basket preparation as before. I was getting more frequent channeled shots, but I really didn't pay this a lot of attention, being enthralled with owning a new machine and the fact that it didn't make a racket every time I pulled a shot.
<aside; am I the only person out there who has noticed that this whole espresso passion is a moving target, and as soon as we "deal" with one "problem," we end up creating others?>
Later, more than a year later, I decided to bring the vibe machine back up from the basement and in casual use of the two machines it dawned on me that it was "easier" to pull a good shot on the vibe than on the rotary, an obvious observation that hadn't registered with me before that time. Subsequently, Michael Teahan suggested in a phone call, when I complained about channeling on the rotary, that I put in a delay timer on the rotary pump plus a regulator on the input water line, giving me a regulated preinfusion water pressure preceding the all-out 9 bar assault from the rotary pump.
Later still, I played around with ~14g dosing and in short order discovered that I preferred the taste profile of the lesser-dosed shots, plus, there was virtually never a channeled shot with the lower dose range no matter how little basket preparation I did (mirroring the observations any home espresso enthusiast would have on a visit to Italy where the baristas do virtually nothing in basket preparation but seem to effortlessly produce decent shots).
My point in recounting this history is to say that the thing that changed in my own personal experience was the purchase of a rotary machine that lacked any semblance of preinfusion, as is easily confirmed by any owner of a modern D1 Cimbali Junior who uses a PF manometer to calibrate the machine; the pressure ramp up to 9 bar is immediate, whereas with a similar vibe machine the time it takes to get to 9 bar is about 6 or 7 seconds with a gradual ramp up.
As a result of this experience it is obvious to me that the Cimbali group and standard double basket has no problem with updosing (at least to 19g), rather it is the way that Cimbali has implemented the changeover to rotary pumps, e.g. no gradual pressure ramp up and no preinfusion. For anyone who wants to overcome this "limitation," the delay timer modification is a simple method that gets the rotary pump to behave more or less like a vibe pump, and this will eliminate frequent channeling assuming at least acceptable barista technique.
It is not the Cimbali machine design or group that is intolerant of updosing, rather it is the absence of any delay in the pressure ramp up, e.g. NO preinfusion.
Again, when all is said and done I no longer like the type of shot you get from updosed shots, but I'd have no problem making them on my Cimbalis, until the cows come home, if that is what I wanted to make in my house on my equipment.
It occurs to me now that Cimbali simply swapped in a rotary pump and motor (plus lots of electronics) in place of the vibe pump, without giving much thought to what this would do to the sort of puck that lots of people here in North America prepare. Their machine design process presumes the use of the sort of dose that you find in Italy, e.g. 12-14g for a double basket. If you eliminate the poor man's preinfusion that you get with a vibe pump by switching over to a rotary pump, and if your basket dose is ~14g, it doesn't matter; you still don't channel. But, if you updose, this is where the end product really suffers unless your basket preparation is nearly perfect, if the puck is to be assaulted with 9 bar from the first second.
ken