The paddle GROUP was featured on the GS series of machines from La Marzocco. The sheer genius of it was that it incorporated a saturated grouphead and a three stage paddle which the barista would slide on the horizontal plane from the middle-left side of the group, over to the right, and back, to brew a shot. Stage one in the movement would open the valve from brew boiler to grouphead, providing line pressure (or in the case of a portable system, neutral pressure) saturation, or preinfusion of the coffee. No pump activation, no harsh blasting of the bed of coffee. Once moved further to the right of the group, it would engage the pump, and start the active brewing of the shot. The Barista controlled preinfusion. Once the shot was completed, moving it back to the preinfusion stage or closed would activate the 3 way solenoid, pressure relief, and basically reset the system to brew again. Great system that let the Barista really control preinfusion for honing the quality of the shot. Nothing else like it, save for piston lever machines where your "pause" controls preinfusion.
jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Wed Nov 16, 2005, 5:56am Subject: Re: Introducing the La Marzocco GS3
BGN Said:
Jim. This is very interesting. Is it your opinion then that the E-61 looses some of it's design advantage by being attached to a non-HX machine? For example, I am considering the Quickmill Elaine and was not considering an HX machine because I am more concerned about the espresso than steam. But if the HX design improves the temperature stability of the E-61 group head then perhaps I should re-think. Barry.
I wasn't clear. The temperature stability of the big single boiler (Eliane) or double boiler (brewtus) E61 machines is as good as from the HX machines, and it requires a lot less flushing. It is better than machines like the Techno or S1 whcih don't have any group heating arrangement. And it is as good as the untweaked early LMs with the poorly dsigned flowmeters and banjo tubes. However, the latest set of flooded heads from Synesso, Schomer-mod LMs, and now this new stock LM head, seem to have ratcheted things up a notch.
If you're south of 4K, you're not going to do much better than a Brewtus or PIDed Eliane in terms of stability.
Functionally none, both are manual pressure relief valves with a no pressure preinfuse in the middle postion. Both will require mains connection to work properly -- on the Giotto and the tank GS3 opening the valve without running the pump will just trickle some water onto the puck since there is no pressure beyond thermal expansion to create a flow.
Of course, since the machine is set up to pulse the pump now, this could be cured by a very short pulse on the line when the paddle is put to the middle. The capacitance of the brew boiler will absorb most of the pressure wave, and the actual presure on the puck probably wouldn't get very high. I wouldn't be at all surprised if Bill hadn't thought of this ;-)
mdreuben Senior Member Joined: 20 Oct 2002 Posts: 188 Location: Cleveland Expertise: Professional
Espresso: La Spazialle VII, Electra... Grinder: Mahlkonig K 30 ES Vac Pot: Yama Drip: Say No To Drip! Use the Eva... Roaster: Sonofresco, Gene Cafe,...
Posted Wed Nov 16, 2005, 6:24am Subject: Re: Introducing the La Marzocco GS3
Thanks for the replies! Is there a diagram somewhere of the mechanics?
I'd agree...although there was a thread by Gary H in which he mentioned measuring shot temperatures of his Zaffiro over a period of time. My understanding of his observations (and my possible erroneous deductions) is that there is a thermal equilibrium set up between the boiler (hotter) and the E61 group (cooler) when the machine is idle. As one pulls shots (especially in rapid succession) the boiler water heats up the E61 group. That group will eventually cool down and return to equilibrium, but it takes time. Gary has a non-PIDed Zaffiro, but he used a large copper block to speed the re-equilibration of the grouphead. My take home message is that the intra shot temp stability on these machines is very good, and the inter-shot stability is good if you allow the E61/boiler to reach thermal equilibrium between shots.
I haev a PIDed Amica, and see about a 30 degree (F) difference between where my thermocouple is mounted (on the side of the boiler, under some self-installed insulation) and the actual brew temperature (measured with a thermocouple that has since gone belly-up). The PID does a good job of maintaining a stable boiler temperature, but the temp at the brewhead can get too hot if shots are pulled too quickly. (ie running water through the grouphead heats it up faster than the thermosyphon effect).
Enzo Senior Member Joined: 17 Feb 2005 Posts: 151 Location: Bay Area Ca Expertise: Just starting
Espresso: Pavoni PubS , and custom Grinder: Mazzer Mini Vac Pot: NA Drip: NA Roaster: NA
Posted Wed Nov 16, 2005, 8:32am Subject: Re: Introducing the La Marzocco GS3
andys Said:
Getting into an argument (even a polite argument) about whether there are compromises was not the point of my post. But digital control of extraction pressure profiling is soon going to be de rigueur for aficionados.
Of course I was shooting my mouth off when I predicted that the "GB3.2" would have it. But you'll see, it'll come. Several folks, including John Bicht and Jim Schulman, are reporting interesting things from pressure control experiments.
Amen, Andy. I'm sure this is a very nice machine, home or otherwise. But state of the art? IMHO not anymore. The fact that it still uses old pump technology says it. Soon I'd like to show some CG'ers what I mean. I have my 3 group Synesso running three different group designs. Two are totally adjustable ramp up or down pressure delivery, and the third is a stock Synesso group, just to have for comparison. The stock Synesso is a very nice machine as well, however, no one that's tasted the different types has said they prefer it anymore. The difference is taste, clarity and mouthfeel, and believe it or not, really good shots are more consistent.
I would say it won't be long before this technology is put into new machines, and the rotary(at least at the aficionado level) will be no more.
houdina Senior Member Joined: 1 Sep 2005 Posts: 56 Location: Northen New Jersey
Espresso: LM SMAL, GS3 Grinder: Versalab M3
Posted Wed Nov 16, 2005, 8:37am Subject: Re: Introducing the La Marzocco GS3
The paddle GROUP was featured on the GS series of machines from La Marzocco. The sheer genius of it was that it incorporated a saturated grouphead and a three stage paddle which the barista would slide on the horizontal plane from the middle-left side of the group, over to the right, and back, to brew a shot. Stage one in the movement would open the valve from brew boiler to grouphead, providing line pressure (or in the case of a portable system, neutral pressure) saturation, or preinfusion of the coffee. No pump activation, no harsh blasting of the bed of coffee. Once moved further to the right of the group, it would engage the pump, and start the active brewing of the shot. The Barista controlled preinfusion. Once the shot was completed, moving it back to the preinfusion stage or closed would activate the 3 way solenoid, pressure relief, and basically reset the system to brew again. Great system that let the Barista really control preinfusion for honing the quality of the shot. Nothing else like it, save for piston lever machines where your "
I think one thing left out about the GS paddle group is that the valve is in the brew group helping with temp stablity and is why some perfered it to the Linea along with the line pressure preinfusion.
Here's a block diagram of a pourover HX machine like the Giotto; however, the three way valve at the group is the same for all commercial pump machines. When not in operation, the path from the group to the driptray is open, and the HX is blocked (thermosyphons have separate plumbing lines). When in operation, the path from group to HX is open, and that to the drip tray blocked. When the shot ends, opening the path to the driptray relieves the pressure and allows immediate PF changes, it also prevents coffee from seeping back into the HX (or brewboiler).
In most machines, the valve is operated by a solenoid which switches along with the pump. In other words, when the valve is open to the hot water source, the pump is always running.
In the E61 and paddle group, the valve is opened manually and is decoupled from the pump switch (the levetta on the E61 and button beneath it; and a similar, although concealed arrangement in the paddle group) This means one can open the valve, leave the pump off, and soak the puck with mains pressured water (1 to 2 bar). When the mood strikes you, you can then turn on the pump. On the paddle wheel, this is more easily done, since the soak position has its own detent. On the E61 on has to push the levetta nearly all the way up, but just before the cam pushs in the switch, so it takes a few minutes practice (with the PF off to see the water running).
The same thing could be done on any conventional machine by simply wiring the solenoid and motor to a rotary three position switch, so the middle position turns on the solenoid, and the full position the motor as well. Why this isn't done all the time, I don't know.
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