Incomplete list of Gravity-fed lever machines - Page 2

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hbuchtel (original poster)

#11: Post by hbuchtel (original poster) »

timo888 wrote:Is the Gaggia Achille gravity-fed? It looks to be pressurized.
The Achille is very interesting, the boiler is at steam-pressure/temperature, and has a thermosyphon (I think) loop going around the piston-chamber. The brew water feeds directly from the (un-pressurized) tank on top, and relies on gravity and maybe suction to pull the water into the piston-chamber, where it is brought up to brew temp by the water flowing in the group head. So it is a gravity-lever-hx . . .

There is a good link and discussion in these threads- "Schematics of the Gaggia Achille" and "Anyone seen, used, or own the Gaggia Achille?"
timo888 wrote:Gaggia Gilda 1948
Nice! Do you mind if I add it into the first post?

It kind of reminds me of a giant beetle! Are those wood handles?

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timo888

#12: Post by timo888 »

hbuchtel wrote:Nice! Do you mind if I add it into the first post?
It kind of reminds me of a giant beetle! Are those wood handles?
I believe its claws and ovipositor are of bakelite.

It's not mine, Henry -- saw the pic on the 'net and nicked it, in the name of journalistic Fair Use.

Regards
Timo

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hbuchtel (original poster)

#13: Post by hbuchtel (original poster) »

timo888 wrote:I believe its claws and ovipositor are of bakelite.
:) :) :) Do you think Les (Thor Tampers) could be convinced to turn a wooden ovipositor?
timo888 wrote:
It's not mine, Henry -- saw the pic on the 'net and nicked it, in the name of journalistic Fair Use.

Regards
Timo
. . .put the Gilda under "open-boiler design," does that seem right? ie could be opened while on?

I also wish to pay tribute to the Honorable Mister J.F.Use, and snuck in a photo of the Achille taken by Jojolever :)

Henry

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timo888

#14: Post by timo888 »

hbuchtel wrote:. . .put the Gilda under "open-boiler design," does that seem right? ie could be opened while on?
I think the Gilda was pour-over but multi-shot, evolving from the likes of the Faema Baby:


hbuchtel wrote:Do you think Les (Thor Tampers) could be convinced to turn a wooden ovipositor?
Maybe if you asked him nicely. But I have trouble convincing anyone to do anything, Henry. Quickie Corp hasn't taken me up on a 45mm brush for filter baskets; HB-Creminites aren't showing much interest in mounting a pressure gauge to the boiler neck of their Creminas; MiniMoka won't re-release the MiniGaggia with one-way valves to keep the boiler from getting fouled; Izzo.cz aren't leaping at the chance to hit the U.S. market with a dual-boiler (one open, one pressurized dedicated to steam) gravity-fed spring-powered lever machine and, as for Les, well, he hasn't taken me up on a 22-second shot-timer made from desert ironwood or coffee burl loaded with powdered diamonds:


Regards
Timo

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timo888

#15: Post by timo888 »

hbuchtel wrote:... the boiler [of the Achille] is at steam-pressure/temperature, and has a thermosyphon (I think) loop going around the piston-chamber. The brew water feeds directly from the (un-pressurized) tank on top, and relies on gravity and maybe suction to pull the water into the piston-chamber, where it is brought up to brew temp by the water flowing in the group head. So it is a gravity-lever-hx .
Henry, this explanation puts my overheated brain into a thermosyphon loop. It looks to me as if the water is not being gravity-fed into the group. Water level can fall to below the group port, right? 'Achille' is an apt name. Its fatal weakness (from the point-of-view of temperature stability) is the pressurized boiler.

I believe we need to summon a synod to decide the question of whether the Achille belongs in this venerable company.

Regards
Timo

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peacecup

#16: Post by peacecup »

So now I finally have to ask why the pressurized boiler has a less stable operating temperature?

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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timo888

#17: Post by timo888 »

peacecup wrote:So now I finally have to ask why the pressurized boiler has a less stable operating temperature?
PC
http://www.iapws.org/faq1/boil.htm
Regards
Timo

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timo888

#18: Post by timo888 »

This Caravel Little from the 1970s turned up in another thread; might as well add it to the list here :)


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hbuchtel (original poster)

#19: Post by hbuchtel (original poster) »

peacecup wrote:So now I finally have to ask why the pressurized boiler has a less stable operating temperature?

PC
It isn't that the boiler temp is unstable, it's that the brewing temp is unstable. Doesn't necessarily mean the espresso isn't good, but rather it is a challenge to get the water to a good brewing temperature.

Inside a boiler at steam pressure the water temp is far above the range of acceptable brewing temperatures. Lever machines with this design rely on the exposed metal group head to absorb heat from the couple ounces of water you will introduce to the coffee.

After a certain amount of time or certain number of shots the group head gets too hot to perform it's heat-absorbing function, and you get unpleasant shots.

With the gravity-lever or open (unpressurized)-boiler machines in this topic the whole shebang (boiler, group head) is kept at brewing temperature, so getting a good shot should be much easier.

Another interesting thing about comparing pressurized-boiler and open-boiler designs is that they will have different temperature profiles during the extraction. Pressurized-boiler designs should start out hotter and cool a bit, while open-boiler designs should have a flatter profile. I don't know how these two profiles would effect the taste.

Henry

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hbuchtel (original poster)

#20: Post by hbuchtel (original poster) »

timo888 wrote:This Caravel Little from the 1970s turned up in another thread; might as well add it to the list here :)
Cool. Where did you find that image?

I have to say I prefer the elegance of the original design over this one . . . the cup warmer would come in handy tho!

Henry