Post makes no sense. How the hell is anyone on this board supposed to know, except maybe giving some theoretical guess? Since you are the one with the CC1, it seems you are the best person to answer the question. Just pull shots with both options and see if any difference.
i learned something new today(that the preinfusion doesnt use full pressure). i wonder what amount of pressure is being used. With the portafilter locked and the coffee compressed, the addition of water onto the coffee has to have a certain amount of pressure. would be interesting to find out what the exact pressure it was using and maybe find out how much water is being used in the preinfusion.
The question makes perfect sense to me. The manual does not really answer it though.
I don't know much about how vibe pumps work, but I would be surprised if you can vary the pressure on it. I would think the only other way to create a low pressure stream would be a separate low pressure path to the brew head. That seems like extra expense in a machine that is designed for maximum bang for the buck.
From what I understand, a vibe pump takes time to get up to maximum pressure. I wonder if their pre-infusion takes advantage of this?
You could try emailing Crossland directly to see what they say.
I found your thread here after watching that same SCG video, because I was wondering the same thing. I also have the CC1, and I think you're right about the 2 scenarios being identical, although I have not yet tried this myself. We can hear in the video that the vibe pump sounds the same during preinfusion as it does during the rest of the shot. Supposedly vibe pumps take a few seconds to get up to full pressure, so I could understand preinfusion maybe working if it is along with a short pause. A zero wait time simply means the pump is on the whole time and therefore comes up to full pressure the same way it would with 0 pre and 0 wait, I think...
Watching the SCG video again it certainly looks like full pressure is coming out the group during PI. I agree that an email to Bill would get an accurate answer to how the CC1 does pre-infusion.
With a Rotary pump plumbed in the pressure during pi would be only line pressure with no pump. Vibe pumps usually use a PI chamber to do PI, the ramp up of pressure with a vibe pump is not exactly PI but is definitely more gentle then a rotary pump that is almost instantly at full pressure the moment it is activated.
It would be nice if this thread continues from pure speculation to facts and measures. Vibe pump pressure is proportional to flow. This is key, but some pressure is required or the water won't make way into the puck quick enough to work.
What does the pump actually do during CC1 pre-infusion? What is the pressure profile? What is the flow profile?
.... of course it will matter to the shot; it's all over in 25-30 seconds. The extraction flow at every second will make a difference.
My CC1, outputs the same volumes in both scenarios with no PF attached - about 275ml in 28 seconds.
I don't know if it does soft pre-infusion at the beginning with a basket under pressure, it might, but I don't have a manometer.
I do know that with simple adjustments in grind (Baratza Preciso), I can get between 2 and 3 oz doubles (I target 2.5 oz doubles in 30 seconds). I used to pre-infuse for 2-3 seconds, dwell a few more for a ~35 second shot, but now I just do straight 30 seconds, and adjust the grind for taste and overall volume.
I actually like it this way, rather than obsess with OPV valves and tuning, I like to just be able to adjust the grind. The OPV on this unit is set great, but you do need a good grinder for full control. I like the Preciso with the CC1.
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