jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Fri May 6, 2005, 6:17pm Subject: Re: The infamous paddlewheel group
It's LM's answer to the E61. A huge external group whose paddle at the top works like the lever on the E61, operating the 3 way valve and activating the pump. The group is massive and hollow, filled with boiler water to keep it warm.
I do not know if the originals were on HX machines and jacketed by the steam boiler -- the legendary machines are the GB1 and GB2 of the 1980s, which are dual boilers and had the group jacketed with brew boiler water. In any case, it's another one of the super-massive, ultrastable brew groups. The consumer machine looks like a miniature GB1, and in terms of technology, is a direct successor.
The current LM groups are probably as massive as the paddle wheel, and are also water jacketed, but being inside the machine, they don't have the same aesthetic appeal.
MarkPrince Moderator Joined: 19 Dec 2001 Posts: 5,054 Location: Vancouver Expertise: Professional
Espresso: Frankenstein'ed LM Linea Grinder: Anfim Super Caimano Vac Pot: 1922 Silex Drip: Krups Moka Brew Roaster: Hottop
Posted Fri May 6, 2005, 6:23pm Subject: Re: The infamous paddlewheel group
The paddle group (I've been corrected on its correct name) is a La Marzocco engineered saturated group head that (afaik) goes back to the GS1 machine they manufactured in the 1970s and 1980s.
Saturated group means the entire grouphead is surrounded with circulating water from the brew boiler, keeping temperatures consistently hot inside the group. E61 uses similar tech, but the paddlegroup is, I believe, the largest saturated group ever produced and manufactured for regular sale.
The paddle itself on the old machines is a two stage device. Move the paddle a portion of the way, and you open a path from brew boiler to the grouphead for brewing water at neutral (brew boiler) pressure - usually less than 1BAR. This saturates or preinfuses the ground coffee in the portafilter. If you didn't have the PF in place, you would see water leaking out of the grouphead. This allows the end user to manually control preinfusion, and gives a lot of experimentation ability. When I go to a cafe like Zeitgist in Seattle (home of a four group GS2 with paddlewheels) and see the counter staff (can't call them Baristi) just slam the paddle all the way forward when brewing, I cringe.
Back to the machine: move the paddle further along its horizontal axis, and you engage the pump.
Move it back, and (I believe - maybe Chris T. can confirm) as soon as the paddle reaches the pump.off position, it automatically closes the brew water path chamber and engages the solenoid 3 way for pressure release. Slightly complex system. The new paddlegroups are even more complex - to be married with a GB5 automatic control package, so you have both semi-auto and full auto in the same machine.
Here's a picture of the most amazing paddlegroup machine made to date - Kees Van Der Westen's Speedster machine. Oh, how I lust one of these...
Mark PS... image taken from Kees' site. I hope he doesn't mind.
Michael_Teahan Senior Member Joined: 15 Jan 2004 Posts: 131 Location: Los Angeles Expertise: Professional
Vac Pot: Vintage for collecting only Roaster: None
Posted Fri May 6, 2005, 7:16pm Subject: Re: The infamous paddlewheel group
I have an old GS 1 group in milk crates in the back that I hope to turn into something like the speedster you have pictured.
I rebuilt the head a long time ago and it is actually even simpler than that. The E61 will pre-infuse at full pump pressure because of the pressure regulated accumulation chamber under the group. The GS has no chamber and no solenoids; the water in the brew boiler is under constant water pressure from the building. Whatever pre-infusion pressure you have is determined by the regulator you install before the pump in the machine.
Pushing the paddle just shy of full stop allows water to enter the group without engaging the pump pushed by water from the building. Pushing it the final half inch or so pushes a lever in the back of the group that activates a micro switch activating the pump.
When the paddle is returned to rest, passages in the group depressurize the head so that you can remove the portafilter.
Because these machines had no PI chamber, you could only pre-infuse one group at a time or all engaged groups simultaniously. Same problem with the Synesso, but not with accumulator based PI groups.
LM patented a saturated group PI system years ago to satisfy inquiries from there biggest fan (I believe) but never put it into production. Synesso should look into it for a PI system that is more user friendly than the one they have now, where you have to weait for one group to finsh before you can PI the next group.
LM's never ran HX as far as I know. Also, the LM isn't rely well suited to circulation; there's realy no feed and return path circuit that is conducive to creating a thermosyphon effect.
The paddle on the LM home unit is not an original design GS; it only triggers a brew switch. With a reservoir and a single pump, I don't think it can pre-infuse like the GS. Which is too bad--I'd take a GS over a linea (except that they are beautiful) every day.
The LM group weighs 9.0 lbs. The new stainless ones are lighter, I believe. The E61 (aftermarket) weighs 9.3 The original E61 weighs 11.0
WHOA!!!! I want to say "that looks so cool", but those words don't even come close to how good it looks.
Thanks for the explanation....that's some great engineering they put into the system. I'd love to see one in action in the hands of someone who knows how to use it.
Anyone know a place in San Francisco that has a machine with this system? I'll be there this summer.
jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Fri May 6, 2005, 8:03pm Subject: Re: The infamous paddlewheel group
Michael_Teahan Said:
The paddle on the LM home unit is not an original design GS; it only triggers a brew switch. With a reservoir and a single pump, I don't think it can pre-infuse like the GS. Which is too bad--I'd take a GS over a linea (except that they are beautiful) every day.
I didn't quite follow Bill when he described what he ultimately intended for the head on the home unit. My impression is that the paddle would have the same functions as the original (i.e. manual 3 way valve with an intermediate trickle setting), but that there would additionally be a position that would switch the machine to auto mode - solenoid activated 3 way, auto-dosing, and an auto preinfuse/trickle timer.
naznar Senior Member Joined: 6 May 2005 Posts: 131 Location: portland Expertise: I love coffee
Posted Fri May 6, 2005, 8:30pm Subject: Re: The infamous paddlewheel group
talking about pre-infusion, what about the lever group machine?
id mention a brand new super sexy lever here but i suppose that would break probationary rules. which is why i edited it out...
The lever group basically does all that a paddle does as far as user control. It has a PI chamber, you manually control the time of PI, holding the lever down, then start pressure by letting go. Lever ussually have the whole thermosyphon thing heating the group too cuz theyre mostly HEX machine.
They do lack the pressure release that the paddle groups have. If you screw up and over pack the PF then you have to wait, or dangerously manually release pressure. But on the other hand if you are a tad off in tamping you may manually control the pressure while a shot is being pulled, a thing no push button or paddle can do.
On a lever you may also pre-infuse multiple groups at the same time.
-joel d. hedging on getting myself a two group manual
Yeah, I've been a speedster fanboy for ages. Wonder who actually has them ... Kees only made six
Chris, could you also fill us in about the lever group on the mistrals. Does it give one control over PI, or is it just an on/off thing?
I really like the look of the mistral's lever group thing. No plastic on the top, so you can use it to preheat cups ... but damn those groups would be hot ...
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