Discussion:
Mathematicians Espresso Network
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Marshall
2003-10-18 16:05:18 UTC
Permalink
My favorite coffee quote of the day: "The cornerstone of the home
espresso operation is a good lever-piston espresso machine such as the
Pavoni Europiccola, shown at right. This particular model is the
canonical coffee maker of algebraic geometers worldwide."

Found at Dave Bayer's espresso page:
www.math.columbia.edu/~bayer/coffee.html via "How Stuff Works:
Espresso Machines"
http://home.howstuffworks.com/espresso-machine5.htm.

David Ross is quoted on Bayer's page.

Marshall
jim schulman
2003-10-18 18:36:04 UTC
Permalink
On Sat, 18 Oct 2003 16:05:18 GMT, Marshall
Post by Marshall
This particular model is the
canonical coffee maker of algebraic geometers worldwide."
It is a geometrical machine. I just got an email from someone who
asked me how hard to press the lever. I managed to work out that you
need 395lb or 462lb for 9 bar on a 49mm or 53mm basket, but didn't
know the mechanical advantage the lever gave. I told him to measure,
and practice on a bathroom scale.
--
Jim

(***@ameritech.net)
Marshall
2003-10-18 19:23:22 UTC
Permalink
On Sat, 18 Oct 2003 13:36:04 -0500, jim schulman
Post by jim schulman
On Sat, 18 Oct 2003 16:05:18 GMT, Marshall
Post by Marshall
This particular model is the
canonical coffee maker of algebraic geometers worldwide."
It is a geometrical machine. I just got an email from someone who
asked me how hard to press the lever. I managed to work out that you
need 395lb or 462lb for 9 bar on a 49mm or 53mm basket, but didn't
know the mechanical advantage the lever gave. I told him to measure,
and practice on a bathroom scale.
Gotta love this group.

Marshall
Donn Cave
2003-10-19 04:17:00 UTC
Permalink
Quoth jim schulman <***@ameritech.net>:
| On Sat, 18 Oct 2003 16:05:18 GMT, Marshall
| <***@IHATESPAMearthlink.net> wrote:
[re Europiccola]
|> This particular model is the
|> canonical coffee maker of algebraic geometers worldwide."
|
| It is a geometrical machine. I just got an email from someone who
| asked me how hard to press the lever. I managed to work out that you
| need 395lb or 462lb for 9 bar on a 49mm or 53mm basket, but didn't
| know the mechanical advantage the lever gave. I told him to measure,
| and practice on a bathroom scale.

Hm, I dug up a post on this from April '02, and according to myself,
the advantage is 8:1. I had the force at only 325 lb., but that was
based on a 2.5 sq in estimate of the piston area that may not be
all that accurate. I believe the lever geometry assumed a hand
position pretty near the end. The result is 40 lbs. I have never
tried to check this, but I'm pretty sure 40 lbs will cause some
slightly alarming deflection in the head-to-boiler fitting and in
the base around the boiler. I have been there, the results were
not better.

Donn
jim schulman
2003-10-19 05:31:51 UTC
Permalink
Post by Donn Cave
Hm, I dug up a post on this from April '02, and according to myself,
the advantage is 8:1. I had the force at only 325 lb., but that was
based on a 2.5 sq in estimate of the piston area that may not be
all that accurate. I believe the lever geometry assumed a hand
position pretty near the end. The result is 40 lbs. I have never
tried to check this, but I'm pretty sure 40 lbs will cause some
slightly alarming deflection in the head-to-boiler fitting and in
the base around the boiler. I have been there, the results were
not better.
Hi Donn,

I should have checked the archive; it's obvious in hindsight that
someone here would have worked this out a long ago.

But what you're saying is real interesting -- the vaunted Pavoni
doesn't work at 8 to 9 bar.
--
Jim

(***@ameritech.net)
Donn Cave
2003-10-20 04:59:14 UTC
Permalink
Quoth jim schulman <***@ameritech.net>:
...
| I should have checked the archive; it's obvious in hindsight that
| someone here would have worked this out a long ago.
|
| But what you're saying is real interesting -- the vaunted Pavoni
| doesn't work at 8 to 9 bar.

Had a geometer done the work, I think he or she would have measured
the actual force exerted. The fact that I didn't means that my
analysis doesn't really say so much.

Donn
john bailo
2003-10-19 06:15:23 UTC
Permalink
Post by Donn Cave
| On Sat, 18 Oct 2003 16:05:18 GMT, Marshall
[re Europiccola]
|> This particular model is the
|> canonical coffee maker of algebraic geometers worldwide."
|
| It is a geometrical machine. I just got an email from someone who
| asked me how hard to press the lever. I managed to work out that you
| need 395lb or 462lb for 9 bar on a 49mm or 53mm basket, but didn't
| know the mechanical advantage the lever gave. I told him to measure,
| and practice on a bathroom scale.
Hm, I dug up a post on this from April '02, and according to myself,
the advantage is 8:1. I had the force at only 325 lb., but that was
based on a 2.5 sq in estimate of the piston area that may not be
all that accurate. I believe the lever geometry assumed a hand
position pretty near the end. The result is 40 lbs. I have never
tried to check this, but I'm pretty sure 40 lbs will cause some
slightly alarming deflection in the head-to-boiler fitting and in
the base around the boiler. I have been there, the results were
not better.
Donn
give me a place from which to stand
and a level long enough
and i will brew you a steaming cappucino
Chris Staley
2003-10-19 21:11:03 UTC
Permalink
Post by Donn Cave
The result is 40 lbs. I have never
tried to check this, but I'm pretty sure 40 lbs will cause some
slightly alarming deflection in the head-to-boiler fitting and in
the base around the boiler. I have been there, the results were
not better.
Well, I will digress on the point of better or not better, not ever
having made side by side quality checks (being to difficult with the
poor multiple repeat performance of the pavoni) but I am absolutely
sure that I have applied WAY more than 40 pounds of force to the lever
of my Professional, and only once, when the machine was seriously
choked did I get a slight hiss of steam out of the boiler to grouphead
gap. I would estimate, considering my body mass and the amount of
force I was using that this was at easily around 80-100 pounds. Of
course I didn't measure this, but I am a big guy, and was throwing
most of my upper body weight behind the lever and pushing with one
hell of a lot of effort, enought to still have the groove marks from
the lever handle imprinted in my palm 5 minutes later. Who knows.

I personally would guess that 40 pounds would be the routine amount of
pressure I apply. Maybe I should measure this.

Chris
Donn Cave
2003-10-20 04:54:19 UTC
Permalink
Quoth Chris Staley <***@yahoo.com>:
...
| I personally would guess that 40 pounds would be the routine amount of
| pressure I apply. Maybe I should measure this.

Someone should, anyway. I just now went down and pressed on the
bathroom scale with the heel of my hand. I was surprised how
easily it went to 40 lbs, so maybe I do in fact exert that much
pressure routinely, anyway it's sure not the dire force I thought
it was. The really stiff pulls that bend the works usually take
both hands. Maybe I can lash my spring scale to the handle.

Donn
Jack Denver
2003-10-21 00:59:12 UTC
Permalink
Just put the whole works on the bath scale. When the scale reads 40 lb. more
than the weight of the machine, you're pressing w/40 lbs. of force.
Post by Donn Cave
...
| I personally would guess that 40 pounds would be the routine amount of
| pressure I apply. Maybe I should measure this.
Someone should, anyway. I just now went down and pressed on the
bathroom scale with the heel of my hand. I was surprised how
easily it went to 40 lbs, so maybe I do in fact exert that much
pressure routinely, anyway it's sure not the dire force I thought
it was. The really stiff pulls that bend the works usually take
both hands. Maybe I can lash my spring scale to the handle.
Donn
D. Ross
2003-10-19 11:31:46 UTC
Permalink
Marshall <***@IHATESPAMearthlink.net> wrote:

| My favorite coffee quote of the day: "The cornerstone of the home
| espresso operation is a good lever-piston espresso machine such as the
| Pavoni Europiccola, shown at right. This particular model is the
| canonical coffee maker of algebraic geometers worldwide."
|
| Found at Dave Bayer's espresso page:
| www.math.columbia.edu/~bayer/coffee.html via "How Stuff Works:
| Espresso Machines"
| http://home.howstuffworks.com/espresso-machine5.htm.
|
| David Ross is quoted on Bayer's page.

Not sure I still stand by that quote: first, the statement about Rocky's
burrs was false (I was misled by Rancilio promo literature and Jurich's
book), and more recently, when I compared the grounds of the two grinders
under a microscope I couldn't see much of anything, leading me to distrust
my earlier observations as observational artifacts.

Dave was an early regular on the coffee groups; you might also know him as
the hand model for the movie A Beautiful Mind. We were in college together
but separated by a year so shared no classes.

- David R.

--
http://www.demitasse.net
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