Greg Scace's Commercial Pressure Profiler

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Marshall

#1: Post by Marshall » Jun 11, 2009, 12:31 pm

At the newly-opened Venice Intelligentsia (Food GPS photos & story here: http://www.foodgps.com/intelligentsia-venice-day-one/), the mechanical centerpiece is the much-debated, much modified La Marzocco GS/2 (TerryZ's step-by-step photoset here: http://www.flickr.com/photos/w1r3d1/3314398749/). [Links edited]

I dropped by yesterday and had another look, while Chris Owens made a vac pot of a special Kenyan lot for us. The LM is directly behind the brew bar section of the shop and is apparently being reserved for special coffees. The other three espresso stations are served by Synesso's (tricked out with clear panels and wood accents).

I noticed a large and mysterious black box under the GS/2 with red digital readouts. This, Chris said, was the pressure profiling control center, which was created by Greg Scace. Greg, any details you can discuss here? Was this the same controller design as for the LM prototype at the Atlanta SCAA Exposition?

Chris mentioned that an important (and overlooked) feature of the Atlanta machine was that it could memorize the progressive infusion paddle motions of the barista, so that the pressure profile would be easily repeatable when a shop is busy. Very intriguing, indeed.
Marshall
Los Angeles

gscace

#2: Post by gscace » 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

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Marshall

#3: Post by Marshall » Jun 24, 2009, 6:51 pm

Thanks, Greg. I take it we shouldn't be expecting the home version any time soon.
Marshall
Los Angeles

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RegulatorJohnson

#4: Post by RegulatorJohnson » Jun 24, 2009, 7:35 pm

variable speed rotary vane pump- nice.
is it the actual pump that is different or just the motor driving it? can you just modify the speed of any pump motor with a controller?

nice work.

cheers.

jon
jon stovall
--
coffeetoolsapp.com

User avatar
dsc

#5: Post by dsc » Jun 25, 2009, 8:13 am

Hi guys,
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.
Care to write more about this? I'm going down the 'motorized bypass valve' approach and I guess that will affect both the pressure and flow of water through the group - lower pressure, less water.
It's the user interface that is the bitch.
So true.

Regards,
dsc.

gscace

#6: Post by gscace » Jun 25, 2009, 9:35 am

Marshall wrote:Thanks, Greg. I take it we shouldn't be expecting the home version any time soon.

Depends on how you feel about downgrade-itis. :D As usual, things get pretty expensive when you build things onesy-twosy. And I'm inherently lazy.

-Greg

gscace

#7: Post by gscace » Jun 25, 2009, 9:44 am

Both are different. The motor driving it is really a rotating magnetic field, with the pump magnetically coupled to it. the pump has no protruding shaft, which eliminates a shaft seal, improving reliability. There ain't no motor shaft neither, which improves reliability and consumes less electricity. It's a pretty neat system, really.

WRT driving normal shaft-driven pumps - I don't think the pump cares what drives it as long as it can connect to it, and as long as the power source has enuff oomph.

-Greg


RegulatorJohnson wrote:variable speed rotary vane pump- nice.
is it the actual pump that is different or just the motor driving it? can you just modify the speed of any pump motor with a controller?

nice work.

cheers.

jon

CafSuperCharged

#8: Post by CafSuperCharged » Jun 27, 2009, 4:39 pm

Greg,
Are you referring to the small Fluid-o-Tech pump with integrated motor (magnetic coupling) and control box?
(Well, the motor/pump is small maybe at 125x125x114 mm but then the control box is about the same size.)

Did you interface to that control box then?

Regards
Peter

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Arpi

#9: Post by Arpi » Jun 27, 2009, 5:20 pm

Hi.

Could you use an of-the-self variable speed motor controller to feed a rotary pump? You would have a knob to control the speed or use a programmed microcontroller. Why would that not work?

TX

User avatar
dsc

#10: Post by dsc » Jun 27, 2009, 6:06 pm

Hi guys,
Why would that not work?
I think a majority of VFDs can't work with motors supplied with a start capacitor. Besides they are mostly suited to drive 3phase motors, which don't need a start cap anyway (although I've seen 1phase versions as well, a bit on the expensive side though - around $350).

Regards,
dsc.