First ever lever pull pressure mod

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Alchemist

Postby Alchemist » Oct 29, 2006, 2:01 pm

Well, I think it is a first. Back in the thread "Peppina Marries MiniGaggia" there was a brief discussion of attaching a pressure gauge to the piston to monitor the pull pressure. Disregarding the spirited discussion about the necessity :), Happy Tamper offered to send me his lever machine to "play" with and modify if I could.

I am going to outline just what I did, step by step, should anyone else want to follow in our footsteps, but I will start off this thread with a Final photo.

In addition, the whole point of this exercise, I want to experiment and document how pull pressure profiles affect the shot. Are isocratic best, does a decay work best, are we actually at 9 bar? That whole thing. Real data :lol:

It is not quite finished, but is very close. While I have people here, I wanted some advice before final assembly. The machine has been apart for a couple months now. Upon test fitting everything, I notice the lever gaskets are very tight in the group head. Should I lubricate them. They are fine and pliable. I would prefer not to have to get lubrication just for this little job if it can do without it, but also don't want to have to break some locktight to add lubrication should there be leaks due to lack of lub. Anyone care to give me some experience based advice?

Image

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Disregard the nail as lever pin - I left the pin at work. Sigh - almost done.
John Nanci
Alchemist at large
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LMWDP #013

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mogogear

Postby mogogear » Oct 29, 2006, 2:09 pm

"Pay no attention to the man behind the curtain"

So John, it appears you have bored down through the piston shaft!! Good for you. That scale on the gauge looks like you will have the upper reaches of force covered. I am so relieved to know you have not been whiling away your time hoping to turn cocoa beans in to gold.... :wink: :wink: I can't wait to see how the pressure ramps up
greg moore

Leverwright
LMWDP #067

happytamper

Postby happytamper » Oct 29, 2006, 2:45 pm

Hi John,

The mod looks super cool, a first in espresso history. Lots of gauges all over the place.

I am glad my old brass Ambassador made the international trip to help in this process. Looks like alot of new coffee data for lever enthusiasts is now a possibility.

Willi Wonkas chocolate factory has now expanded to coffee. :lol:

As for the Lubrication. The gaskets are relatively new so they may be a bit tight. It is always good to have some though I find it disapears with time and the water becomes the lubrication so lube is not absolutely necessary, or at least this is what happened with my Europiccola.

Look forward to seeing all the experiments.

All the best,

Mitch
Mitchell
LMWDP #77

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Alchemist

Postby Alchemist » Oct 29, 2006, 2:51 pm

happytamper wrote:Hi John,
As for the Lubrication. The gaskets are relatively new so they may be a bit tight. It is always good to have some though I find it disapears with time and the water becomes the lubrication so lube is not absolutely necessary, or at least this is what happened with my Europiccola.



OK, then if there is no counter suggestions, I will not worry about additional lubrication. It went together fine.

And right you are Mogo, hole through the center - but it was not nearly that simple. More of that later....
John Nanci

Alchemist at large

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LMWDP #013

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espressme

Postby espressme » Oct 29, 2006, 8:31 pm

Alchemist wrote:OK, then if there is no counter suggestions, I will not worry about additional lubrication. It went together fine.

And right you are Mogo, hole through the center - but it was not nearly that simple. More of that later....


Hello Alky,
Congratulations! You did the almost impossible! I found a photo a while ago of one of the rip-off machines with a gauge as you have it.
I'd love to know how you solved it!
Best Reagrds to All,
Sincerely
Richard / Espressme
richard penney LMWDP #090,

bobcraige

Postby bobcraige » Oct 30, 2006, 7:48 am

How do you expect the purge the air from the gauge path?
Bob Craige

LMWDP #7

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Alchemist

Postby Alchemist » replying to bobcraige » Oct 30, 2006, 8:44 am

Either it will work with an air in the path (pressure is pressure after all), or should I find it does not work for what ever reason, the gauge could be loosened to purge the air.

The pathway is very small, built to accommodate air. I doubt there is a ml all told. I expect some compression, but again, pressure is pressure, and the water should be re-expelled after the shot should some compress up the pathway.
John Nanci

Alchemist at large

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LMWDP #013

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hbuchtel

Postby hbuchtel » Oct 30, 2006, 9:52 am

When there is a gauge measuring boiler pressure there is certainly air in the system . . . why would it be a problem?

EDIT: re-reading this thread I realized above sentence doesn't make much sense, what I meant is gauges that measure boiler pressure (such as the one on the end of the sight glass on the G. Factory) measure accurately in spite of there being air in the boiler, so why would a gauge measuring brew pressure require that the air is purged?

Will John have to release 'false pressure' as it warms up? :)

Henry
LMWDP #53

happytamper

Postby happytamper » Oct 30, 2006, 1:00 pm

Seems to me, from my engineering days, air will always stay at the top. :shock: Especially if we are letting a short preinfusion occur.

I wonder what pressure we will see on our pulls with this apparatus in place. I will bet some of us are pulling at 20 bars and others at 6.

Maybe this machine should do a tour, to get a larger sampling of lever practises. Or as a training tool. However I am excited to get my brass beauty back to Montreal for a while, Of course only after all our Alchemist has exhausted all testing and has had a thoroughly good time with it. :lol:

Now we have to invent a sieve for measuring the varying degrees of grind. :twisted:
Mitchell
LMWDP #77

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espressme

Postby espressme » Oct 30, 2006, 3:31 pm

happytamper wrote:Seems to me, from my engineering days, air will always stay at the top. :shock: Especially if we are letting a short preinfusion occur.
I wonder what pressure we will see on our pulls with this apparatus in place. I will bet some of us are pulling at 20 bars and others at 6.
Maybe this machine should do a tour, to get a larger sampling of lever practises. Or as a training tool. However I am excited to get my brass beauty back to Montreal for a while, Of course only after all our Alchemist has exhausted all testing and has had a thoroughly good time with it. :lol:
Now we have to invent a sieve for measuring the varying degrees of grind. :twisted:



you sirrah have a wicked mind. :P And, unfortunately have me thinking!! :twisted:
Enjoy
Richard espressme
richard penney LMWDP #090,