Positive pressure, PID Pavoni: world domination begins - Page 4

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matadero210 (original poster)
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#31: Post by matadero210 (original poster) »

Hi All,

Some quick snaps of the now working Pavoni, plumbed-in, with PID control, naked portafilter, regulated infusion pressure, and BREW PRESSURE GAUGE! (Forgive the shouting, but you can imagine my caffeine level).





The first shot shows the j-b welded tubing and gauge. Just to remind everyone, it connects to a 0.040" hole outside the cylinder, but inside the screen o-ring. The second shot shows the supply plumbing with infusion regulator and gauge (analagous to the normal gauge on the Pavoni Professional). Note the large expansion tank--I still like the feel of it better than the back-pressure relief valve (not shown). All parts come from mcmaster.com, which is quite addicting.

Must go now, can provide more detail over the weekend (do ask if you have specific questions). I did pull 2 shots on this at 8 bar--better than ever! Anyone in Silicon Valley is welcome to swing by for a pull or two.

raj

PS: would love to hear from anyone with ideas for how to improve on this. I can think of one major problem: poor insulation. This results in the heater coming on too often. Also, right now the controller uses its built-in mechanical relay. This weekend I'll switch to SSR, so maybe temperature will be more steady. I just wish I could think of a way of insulating the Pavoni without making it look terrible. In the absense of any new ideas, I may start working on a roaster or mill ....
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espressme
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#32: Post by espressme »

"I just wish I could think of a way of insulating the Pavoni without making it look terrible. "
You could very easily make a sheet copper boiler wrapper and top. It could be held by insulation pressure with a a couple screws. In other words, make a sheet, curl it and leave room for the sight glass mounts where it comes together. put a machine screw top and bottom. Hammer out a cone that slips tightly over the top of the cover and fits close to the boiler neck. A few hours work total. :twisted:

Good luck!
richard
richard penney LMWDP #090,

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matadero210 (original poster)
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#33: Post by matadero210 (original poster) »

Hey Richard--

Good idea. I think all Pavoni's could benefit from boiler insulation, though without positive pressure you would never want to leave them on for long. I worked with Suyi at auberins.com and tweaked the controller to +-0.5C and <1min to recover between shots. Now I need to get that Robur grinder project worked out.....

raj
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mogogear
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#34: Post by mogogear »

This thread has been a smile from start to where it is now--------

FrankenPavoni meets the Tinman from the Wizard of Oz and after being pressured ( ;>)
........... steals his coat, bad * dap * dap!
greg moore

Leverwright
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espressme
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#35: Post by espressme replying to mogogear »

With steam and a whistle we will have a hoot! :twisted:
rp
richard penney LMWDP #090,

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matadero210 (original poster)
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#36: Post by matadero210 (original poster) »

Hi all,

Just a quick update. The system is working fine. I did some tweaking to the PID to get +-0.4C and a resonably fast shot-recovery time (less than my grinding time = 1min). I lathed a 1.7kg stainless tamper that I'm experimenting with. Reg Barber's are too small. My tamper can't sit flat on the bottom of the basket: it stops 2-3 mm above the bottom (the puck is thicker, of course).

I'm curious about the fine-grind/light-tamp extremists. So I adjusted the Zass down and started tamping with just the weight of the tamper (1.7kg = 3.8#). It works fine and make an interesting cup, but very aggressive on young roasts. I wonder if 5-7 days is needed, because at 4 days past roast the cup is good, but wild.

Lastly, I still get a 'donut' during pre-infusion, although the pull is more uniform. I'll read up on it, but any suggestions are welcome. I distribute with WDT and leave the surface flat before tamping. Does Stockfleth's Move result in a concave distribution that would limit side channeling?

raj
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Stuggi
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#37: Post by Stuggi »

Just a quick question. Could one just PID a M-model La Pav.? I mean without the water inlet. Does the La Pav work properly with just 93 degrees centigrade water in the boiler? And is it possible to attach the TC on the outside of the boiler?
Sebastian "Stuggi" Storholm
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hbuchtel
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#38: Post by hbuchtel »

Hi Struggi, the problem is that the Pavoni requires a certain amount of pressure to force the water from the boiler up to the group, and that pressure comes from having the boiler at a higher temperature. (ie 93C would not be enough)

There is a good thread by cannonfodder about encountering this problem when putting a PID on his Gaggia Factory lever.

Regards, Henry
LMWDP #53

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Stuggi
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#39: Post by Stuggi »

As I thought... Well oh well, you can't always luck out with these things... ^^
Sebastian "Stuggi" Storholm
LMWDP #136

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matadero210 (original poster)
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#40: Post by matadero210 (original poster) »

I recently started to think about this question, so I chopped the top off my machine and went open boiler. It works fine, but takes some fiddling of the lever to get the chamber full. If you want less than 10 seconds of pre-infusion, it wont work.

But with the longer pre-infusion, it does seem to work. Since I just did the operation, I can't say if the shots are ok--will update shortly.

raj
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