by gscace on Wed Jun 24, 2009 11:11 am
Hi:
Sorry for the tardy response.
the GS2 at Intelly uses 2 different pumps. One is a normal rotary vane pump, and the second is a variable speed rotary vane pump, controlled by a programmable system that uses pressure as a feedback signal. It's the same system that has been at my house for the past couple of years. Now Intelly has one and EPNW also has one.
I put one on a Simonelli Aurelia that was in Simonelli's booth at the SCAA show, in order to demonstrate it to interested folks. Unfortunately it was fairly hidden from view, so it wasn't very noticeable unless I dragged you over there and ranted about it, or you just wandered up, pulled a shot on that machine, then when WTF?
My system is time-based, in that the pressure changes with time, as programmed into the controller. The other possibility, changing pressure according to the amount of water flowing thru the system, is a bit harder for a hack like me to do, but might be a better solution.
LM's system is different from mine. I know some details of things Bill Crossland was working on when he left LM, but they're not for public discussion. It's huge if their system has the ability to learn profiles.
WRT commercial appeal - Folks who have used my system like it and think it opens up fertile ground. I think this isn't news to Andy, Jepy, the guys at LM, and Slayer for that matter. It's the user interface that is the bitch. It's pretty easy to cobble together some parts and make a reliable time-based system, and so I'm building at least one more system. Then you have to learn how to tune and program it. That's reasonable for some folks, but not for a made-for-the-masses device. It's certainly made me think of investing in LabView, so that I could build a less obtuse interface in my spare time, between my real job, job #2 building Scace devices, speedskating, raising a coupla kidzz, making sure that the house doesn't fall down, blah blah woof.
I blathered about the system when I built the first one a couple of years ago. I cross-posted three diatribes about pressure-profiling pumps on here, alt.coffee, and coffeed. I felt justified in doing so because those sites have different audiences. At the time I wasn't sure how to quantify the results. Having used it for a couple of years now, I'd say that the major benefit is the ability to arbitrarily change pre-infusion and pressure profile without needing to consider the internal geometry of the group. This is huge because now a group can be optimized for other parameters besides pressure. That means there is no need for preinfusion chambers, and chambers with spring-loaded pistons, etc. That reduces cost. And it gives whoever sets the machine up the ability to optimize the pressure to the coffee. That ability was previously only available to the designer of the espresso machine. Since the pressure profile is completely tunable, one can then explore pressure space in a way that was not possible in the past. In the past, pre-infusion ramps were dictated by the type of pump being used (lever, rotary, vibe), internal geometry of the group, gicleur size. And previosly, only operator-actuated levers could produce completely variable pressure. Now brew pressure is only limited by the imagination, and the practical constraints of what tastes good.
-Greg
As usual, things get pretty expensive when you build things onesy-twosy. And I'm inherently lazy.
even if it only had 10 positions 
That would be art, like playing the violin.
