Having bought a Gaggia Classic Pro with little more thought than "AVE showed one and it didn't have any electronics in it, and there's a lot of hype about it" I'm now finding all the non-hyped things like the big pressure from the factory.
So the first thing was to measure the pressure ex-factory. I looked on Bunnings website and didn't find the 3/8 to 1/4 female to female adapter that MedaGalax found, so rather than spending about $5 on that I spent $15 on 2 cheap taps (one of which is not fit for purpose) and a few hours making one.

That showed me the factory setting was 13.25 bar.
I measured the spring so I knew roughly what I wanted and couldn't find it locally and didn't want to spend a lot of south pacific pesos getting one from the usual suspects.
So I made an adjustable bit for the OPV to allow the spring compression to be backed off a bit.
Here's the general idea.

Here is the prototype (with the factory spring), which will probably be in place forever. I should have made it from brass hex, but I cut the test M10x1 threads on a short end of 12.7mm round and the 2nd one was ok so I just kept going with that material! Later on I did regret this.

Here it is in place.

And at 9 bar.

Sorry all the photos are dodgy. I've just started using a Mac and don't have the programs I'm used to for cropping and resizing etc on Windows.
I made the female part of the adjustment spring too shallow - it looked ok in CAD but by the time you take the tap lead in etc into account it wasn't really enough.
So a revision would be better and easier to use, but this one is working and not leaking so I think I'll leave it.
I can't say whether the coffee is any good, but it's better than that from at least 2 cafes I go to so that's something!
No grinder yet. I was using supermarket ground coffee... you can imagine how that went at 13.25 bar - the water just rushed through it. Now I have some espresso ground at a local roaster and that's much better.
So the first thing was to measure the pressure ex-factory. I looked on Bunnings website and didn't find the 3/8 to 1/4 female to female adapter that MedaGalax found, so rather than spending about $5 on that I spent $15 on 2 cheap taps (one of which is not fit for purpose) and a few hours making one.
That showed me the factory setting was 13.25 bar.
I measured the spring so I knew roughly what I wanted and couldn't find it locally and didn't want to spend a lot of south pacific pesos getting one from the usual suspects.
So I made an adjustable bit for the OPV to allow the spring compression to be backed off a bit.
Here's the general idea.
Here is the prototype (with the factory spring), which will probably be in place forever. I should have made it from brass hex, but I cut the test M10x1 threads on a short end of 12.7mm round and the 2nd one was ok so I just kept going with that material! Later on I did regret this.
Here it is in place.
And at 9 bar.
Sorry all the photos are dodgy. I've just started using a Mac and don't have the programs I'm used to for cropping and resizing etc on Windows.
I made the female part of the adjustment spring too shallow - it looked ok in CAD but by the time you take the tap lead in etc into account it wasn't really enough.
So a revision would be better and easier to use, but this one is working and not leaking so I think I'll leave it.
I can't say whether the coffee is any good, but it's better than that from at least 2 cafes I go to so that's something!
No grinder yet. I was using supermarket ground coffee... you can imagine how that went at 13.25 bar - the water just rushed through it. Now I have some espresso ground at a local roaster and that's much better.




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