drgary wrote:
To maximize the pressure effect what happens if you grind and dose to a very restricted flow?

We'll see tomorrow.

You should see that the starting temperature of the ground coffee effects the temperature measured in the puck (vs above it) during brew. Ie, bean temp before grinding, heat added by the grinder, heat added by the portafilter and the related time delays all effect the brew temperatures that the beans experience. In other words, consistent brew temp within the grounds (what really matters) is even harder to achieve than above them. For example, 15 grams of warm coffee grinds have a significant temperature effect on 40 grams of hot water, even after accounting for the difference in specific heat.

It's no question and believe me it's known (even by me). But where do you want consistent brew temp. The coffee cake is big. As you see temp at the bottom will differ from the measured temp near the surface. I'm pretty sure if there were a sensor in the middle we would see a third paralell line/curve between. You wouldn't question that either. And you should not forget that "water" getting to the bottom of the coffee cake is not really water more, but more or less coffee extraction.
Secondly there are two many variables wich could ruin your consistent flat temp profile in the coffee cake (changing from double to single basket, grind, tamping, enviromental temp etc). All I want to enjoy my coffee not just the drink but the process as well. I can't imagine a better tool to achieve this than a small lever. If that means a flat temp profile between the cake and dispersion screen than fine. It's a great challenge having temp consistency somewhere in the cake for sure but not worth it (for me). Challenge for me is to pull a great shot with this machine with the given parameters and to know what these parameters are, how can I influence/manage them. I don't see the way (yet) how a flat temp profile in the cake is achievable with a small lever. But I'm open for new ideas. Do you see the option to get a steady temp within the coffee cake with a small lever?

drgary wrote:Keep some things consistent,...........measure the differences in pressure and perhaps temperature. If you can keep the shot time the same. And don't break your machine please to try and make these things work.

Some things are consistent . Really. I'm the one who always pullls. That' my biggest handicap. I think it's easier to fly a Jumbo. Pulling a shot with 4 thermocouples placed, dosing/distributing/tamping, starting at the same boiler and group temp. But I try..... Hopefully it is not going to be a crash landing...

Measure the differences in pressure is a tricky one though...

drgary wrote:To maximize the pressure effect what happens if you grind and dose to a very restricted flow?

Ecco. The new measures (finer grind, the vert. line represents the end of the pull):

Normal pull:



Strong pull:



Slightly deeper temp at the bottom of the basket. 5-7sec shorter pull.

I think one solution of limited temp profiling for the small levers is playing with the lenght of the preinfusion.

But again, the thermocouples were not soldered. Otherwise I don't think we would get completely different measures with a perfectly made Scace thermofilter.

mathof wrote: I wonder if you might be interested in performing the same last set of measurements on it.

Matt

Thanks for your feedback Matt! Of course. Planning to do it soon.