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OPV setting shouldn't impact a proper density puck, right?

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All, trying to get my head around the reason for adjusting the OPV on my new to me Gaggia Classic. I've done a whole bunch of searching, but nothing that exactly answered my question. Closest I got was here.


Right now I am trying to dial in the tamp/grind/dose to just get flow through the machine (a different thread I have). Am I correct that even if you have a machine that has the OPV setting at 12bar, if you have a puck that will flow at 9bar that OPV won't come into play/matter. So if I can't get flow through a puck at a 12bar setting, changing the OPV to 9bar won't change anything for me. I need to dial in my tamp first to allow flow at that 9bar. I'm assuming too dense of a puck needs a higher pressure to get flow through the puck vs a lower density (courser grind, less tamp, less dosing) puck needing more?


So does the lower setting just set the high limit for when you will get flow. It basically forces you to adjust your puck density so that it flows at the lower pressure and then you adjust how to balance the other parameters to get the taste you want?


Is that right or am I still turned around?


Thanks in advance,


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You should be able to get the right flow at either pressure, sound like you need to grind coarser. As soon as you flick the brew switch you should get your shot in 30/35 secs. Get a 0.1g scale off amazon (about a tenner) so you can you use the 1:2 ratio (18g coffee into 36g in the cup)

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Lowering pressure to 9.5 bar is essential for me regarding fighting channeling, proper single shots, taste, everything. The difference is that you will need a concrete puck at 12-14 bar.

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I don't have channeling problems, but I am fighting a flow problem in initially dialing in my machine and grinder that I've got in another thread. Any tamping and I'm essentially completey blocking the flow.


Cloughy, thanks for the suggestion. I did completely clean the brewhead before giving this all a go, so think I'm all set there. Think you are right on the grind, just surprised as the grind level that's getting me flow is outside the range recommended for Baratza. Could be a function of the oily beans too as this really is my first go at all this.

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Try and keep some things the same i.e basket size and amount of coffee for the 1:2 ratio and just adjust the grind. I've found beans give a more consistent flow after they've been rested 7-10 days. Tried new beans in the past and flow was all over her place (was having to keep adjusting the grinder setting) once dialled in after 7 days it's very consistent for me. This being another reason why I freeze my coffee after 10 days rested in 200g vacuum seal bags so I never have to adjust the grinder after dial in.

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