LA42014 wrote:Just a novice here-can you explain this?

In the pressure set video, I do not see any flow out of the gauge, hence the OPV is set to static pressure.

When the puck flows, the pressure may be different.

There is a method using flow debit, which is easier to do without a pressure gauge (it's not as exact but it worked well for me on two occasions).

Tony,

Do you have one of the "older" Gaggia Classic machine (pre-2018 I believe) or one of the newer Gaggia Classic Pro models (2019 or newer)? I had one of the newer ones and like Chris (PIXILLATE) alluded to, it can be a steep uphill battle. I also had a very difficult time pulling a shot that wasn't seemingly bitter and over-extracted.

Aside from temperature instability, I believe my big problem was that the stock OPV was set too high and I found that the OPV on the newer machines is non-adjustable. So with the brew pressure being too high, it forced me to grind finer in order to even come close to the recommended parameters of a 2:1 ratio in the 25 second range. Here's a post that kind of chronicles my progress with adjusting the pressure:
Dealing with high brew pressure on 2019 Gaggia Classic?

If you aren't interested in the DIY approach, Mr. Shades coffee in the UK offers a spring kit so lowering the brew pressure is as easy as swapping out the spring in the OPV: https://www.shadesofcoffee.co.uk/

The other thing I ran into is that I seemed to be suffering from a LOT of channeling... After doing the nickel test, I found that I could only put about 15 grams of coffee into my double basket before failing the nickel test.

Hope that helps!

Josh

OPV springs are also easily available on ebay here in the US. Cutting the stock spring is also an option.

Temperature surfing may help as well. A meat thermometer probe mounted on the boiler can help you figure out how hot it is getting..

I found swapping out the Gaggia for a Profitec 600 solved all my frustrations with the Gaggia