Changing the pstat setting changes the brew temperature, but the temperature of water that reaches the puck at the end of the inflow pathway is drastically different than the boiler water temperature. So, too, the temperature of the stream into the shot glass is lower than what bathes the top of the puck. Even so, knowing the incremental change in the shot temperature for any adjustment or knowing the shot temperature relative to the taste of the shot for a given roast may provide valuable information that one might use to correlate with the reliable reproduction of good shots.

As an apartment dweller, my access to powertools and brazing equipment is quite limited. Having 34 gauge (.006") surgical stainless steel wire allowed me to 'baste' a themocouple (Thermoworks wire stock# 113-362/363/365, 0.5 sec response, ±0.9°F) to the bottom of a double basket. The filament wire fits quite easily through the existing basket holes.
Wires in place, bottom view:

Wires in place, inside view:

It is important to thread the wires through the (in this case, single-spout) PF, since the standard type K fitting will not pass:
TC in place:

Closeup; the last 'stitch between the wires is important to prevent the twisted wire from backing out:

PF in position:

This has just been jury-rigged and it has not seen any serious use yet. I will post a little bit later.

I find this approach interesting.
Actually it has some drawbacks.
For example, now it is almost impossible to wash the filter after brewing.
But I think It is possible to work on it.
Alberto

Nice. One could argue that measuring the temp as the coffee leaves the puck is more representative of what the average coffee grind sees than measuring above it. The latter method ignores the significant cooling effect that the coffee grounds themselves have.

Which is why Greg Scace spent so much time choosing a filling material that would mimic the heat absorption of ground coffee.

This one was pretty cheap to build

Marshall wrote:Which is why Greg Scace spent so much time choosing a filling material that would mimic the heat absorption of ground coffee.

Unless the coffee is flowing through said material and the temperature is being measured after that point, it's not at all the same thing.

SJM wrote:This one was pretty cheap to build
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I think we could all benefit from knowing the details of your project.
Actually, it wasn't bad to wash. Just have to be careful.
For my first run, with the pstat set to .9 bar, I was very surprised to measure the effluent coming out as high as 198-202F,
EDIT: on reviewing the data graph, the temperature ramped up +78°F from the end of preinfusion for the next 15 seconds in what could very well fit to a straight line, then at that point, stayed very steady at 200.7 to 201.7 for the rest of the infusion

assuming (as anyone would) that the temperature did drop as it passed through the puck. The factory setting of this machine, and the settings recommended and in use by most owners, is around 1.2 bar. Eric S set me at .85 bar, and I inched up a bit. I guess I should have listened to him, although the shot was good and didn't taste burned (but it did taste a little like the TC wire smells when it first gets hot). I don't have the complete first run postprocessed to show the curve, yet
EDIT:see above. I wish I knew how to insert an excel chart. It looks a lot like JimG's Alex Dutetto tracing alluded to in the post by erics, below, right down to the temperature values, except my tracing has a small increasing shoulder, not a rising then decreasing shoulder.

I will send you a PM.

jonr wrote:Unless the coffee is flowing through said material and the temperature is being measured after that point, it's not at all the same thing.

Right. It's an approximation. The point was to create a product that would be easy to use and provide useful results. Its adoption all over the world and use as the temperature measurement tool to qualify espresso machines for the World Barista Championship suggests Greg was successful.

The point was to create a product that would be easy to use and provide useful results.

Concur 100%.

This study by a very experienced temperature gatherer also provides some insight - Temperature study of Alex Duetto