# Gaggia experience - why the mods are so important!



## np123 (Dec 15, 2014)

I've had my Classic for a little over a month now, so still very much learning the ropes.

The first modification I made was the upgrade to the Rancilio Silvia steam wand. It's made a huge difference to the milk frothing. Cravendale Green is a great choice too.

I also swapped out the pressurised baskets with a standard basket and got very disappointing results. I kept working on my grind and got to a place where I felt I had the right grind, but still the shot was far too quick. The only way to slow it was to choke it, which would have still been wrong, so I decided I had to do the OPV adjustment.

I managed to get time to do the OPV adjustment this weekend. It took about 30 minutes all in, which is miniscule compare to the enormous difference this turn of a screw has yielded. Whereas before the water was running through in about 10 seconds flat, a 60ml shot of espresso takes a good 28 seconds to come through now. Bags of crema too. The pressure was around 14 bar (static) so a drop of 4 bar to a static 10 bar is quite a drop!

It's been the icing on the cake, as its validated that my grind was right, it was the pressure that was wrong.

The cherry on top was trying out the bottomless portafilter again. I tamped the coffee down, and set the shot ready to go. I backed off a foot or so, fully expecting a shower of coffee, but instead I got a solid spout of coffee straight into the shot glass, which looked sumptuous!

I tried it again and got a little channelling, but every time I do it I get decent results and lovely crema, and it's very, very satisfying!

So the reason I post this is that for any new Classic owners, if there is one thing you should try it's this modification. Makes the world of difference.


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## jeebsy (May 5, 2013)

np123 said:


> a 60ml shot of espresso


Which weighs?


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## np123 (Dec 15, 2014)

jeebsy said:


> Which weighs?


Cough, not weighed the output yet. I have my scales just need to start that, tomorrow morning. You are correct though!


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## jeebsy (May 5, 2013)

I didn't find the OPV made a big difference the speed of my pours, certainly not to that degree anyway.


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## froggystyle (Oct 30, 2013)

Agree with jeebsy. Didn't change the speed for me but more the feel in the mouth!


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## np123 (Dec 15, 2014)

Interesting...wonder why it changed the speed so much for me then?


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## The Systemic Kid (Nov 23, 2012)

Sounds counter-intuitive but running at too high a bar pressure induces back pressure which impacts on extraction yields.


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## jeebsy (May 5, 2013)

Changed your grinder or tamp/tamper?


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## np123 (Dec 15, 2014)

jeebsy said:


> Changed your grinder or tamp/tamper?


I left everything as was. Maybe there was just too much pressure in my case?


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## colm1989 (Nov 17, 2014)

I've just done my OPV adjustment today as well, it certainly does produce a much higher volume! Time to dial in the grinder again! Despite almost doubling my yield (32g -> 56g) it certainly did feel a lot more syrupy than before!


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## BIG ROB (Dec 21, 2014)

Could the finely ground coffee be acting as a non Newtonian fluid? Where the more pressure that's exerted on it, the more solid it becomes.


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## mhv (Oct 17, 2014)

BIG ROB said:


> Could the finely ground coffee be acting as a non Newtonian fluid? Where the more pressure that's exerted on it, the more solid it becomes.


Love non Newtonian fluid...


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## Hugh (Jan 21, 2015)

np123 said:


> I've had my Classic for a little over a month now, so still very much learning the ropes.
> 
> First post and should give you all a good laugh - cobbled together adjustable legs (nuts, bolts, washers, rubber feet, self adhesive foam strip under radiator pipe covers !) which has meant i can now level my machine (by adding in washers as required) and i can get any pitcher under the steam wand without tilting. Now tell me it is too high above sea level...
> 
> ...


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