Bezzera Strega mods - Page 2

A haven dedicated to manual espresso machine aficionados.
Marcje (original poster)

#11: Post by Marcje (original poster) »

bostonbuzz wrote:How are you getting the pressure throughout the shot? You u must have drilled a new hole juuust above the shower screen through the back of the group?
In short: For the manometer on the grouphead, I drilled a hole through the piston + rod, and I had to do some machining in the head to get 'to the ouside world'.
For the manometer in the front cover (+ pressure release), I removed the 2 bottom seals of the piston (only using the top one) and filled them up with teflon rings. Then I put 2 solenoid valves in the feed line, between the HX and the grouphead. One valve open/block the flow from the HX to the grouphead, and one valve release the pressure (into the drain).
Not sure if I would do all of that with a new machine, but ours is quite old and decided to take the risk. So far it's working ok...

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bostonbuzz

#12: Post by bostonbuzz »

I just fully understood what you wrote, thanks for the explanation. Quite a mod to change the bottom 1/2 of the piston!

I was wondering how you got a reading on the gauge and the solenoid to function given that the piston covers the water hole quite soon in the stroke. I just installed one on mine and it's really only useful for preinfusion. That makes sense that the hole being open all the time through to the portafilter would allow for that. The flush function would be important since the group water tube may have some coffee from the exhaust still in there, as there is no back-flushing a lever. Cheers.
LMWDP #353

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Stephane_Paris

#13: Post by Stephane_Paris »

I thought when lever down until the pump fill the group the pressure will go to 9 or 10 bar.. look like around 2 bar on you two videos.
LMWDP #588.

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baldheadracing
Team HB

#14: Post by baldheadracing »

Marcje wrote:... For the manometer in the front cover (+ pressure release), I removed the 2 bottom seals of the piston (only using the top one) and filled them up with teflon rings. Then I put 2 solenoid valves in the feed line, between the HX and the grouphead. One valve open/block the flow from the HX to the grouphead, and one valve release the pressure (into the drain). ...
That's a very impressive mod. Kudos.

Do you have any tips on making the hole in the machine's faceplate for the additional gauge?
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

Marcje (original poster)

#15: Post by Marcje (original poster) »

Thank you! I used this drill and lots of lubricant.
It was a bit nerve wrecking to be honest...


Marcje (original poster)

#16: Post by Marcje (original poster) »

Stephane_Paris wrote:I thought when lever down until the pump fill the group the pressure will go to 9 or 10 bar.. look like around 2 bar on you two videos.

The machine is plumbed and I was using the line pressure, not the pump.

Marcje (original poster)

#17: Post by Marcje (original poster) »

Next useless, but fun mod: First step of connecting the Strega to a pressure monitoring dashboard/app.