Marshall wrote:Apologies, if I went overboard, there. I have a horrible tooth infection and am having root canal work tomorrow morning. Everyone is warned!

Marshall, there I found you!!! my mother is dentist. Consider a trip overseas for my mummy taking care of your teeth (sharp ones ) and to pay honor to my coffee madness (as friends consider and do not speak out in front of me poor guys they are, no?)

I plan to return my borrowed Duetto early next week, so this will probably be the last data set.

The original Gicar PID controller on the US models had a funny quirk with the way offsets were handled. The software in the controller has now been changed so that it is a little more straightforward to use. I received an updated PID controller this week and installed it.

Before letting the Duetto get away, I wanted to do just enough testing to see if the information I posted here previously is still valid for the new PID. Based on a couple of spot checks, I think the answer is "yes."

The boiler surface temperature with the new PID seems to run within around 0.2F of the temp with the old PID. (That variation is well below measurement uncertainty).

Second, I checked the offset between PID sensor reading and actual brew temperatures. But this time I used a little different setup for measuring brew temperatures. In the first round of tests, I used a Scace thermofilter. This time, I used a fine wire bead thermocouple embedded in real coffee[1].

As the plot below shows, the results are very similar, which probably indicates that the offset values I posted before should still be valid (18F with steam boiler on, 20F with steam boiler off, 19F average). I think the results are also another testament to the accuracy with which Greg's device mimics a real puck.



Plot of intrashot temperature profile based on fine wire bead thermocouple embedded in coffee puck approx. 4mm above bottom of basket.

Lastly, in answer to some of the questions that came up regarding the taste of the espresso: simply maaahhh-velous

Jim

[1] Drilled a small hole through the side of a double basket, passed a 30AWG type K bead probe through, and epoxied up the hole to seal it. Basket was snapped into a bottomless PF. The wire turned out to be fine enough so that the puck was not disturbed very much, and I didn't get channeling or spritzes. The sensing tip of the probe was probably around 4mm above the bottom of the puck after tamping.

At the risk of having missed it Jim, did you determine the tuning parameters of the PID beyond the SV?

The objectives of this study were:

* Determine optimum (or nearly optimum) tuning parameters for the Gicar PID
* Examine intrashot temperature behavior
* Examine recovery and intershot stability with a series of closely spaced shots
* Compare behavior with steam boiler on (preheat) vs steam boiler off (no preheat)

Thx
Floyd

floydo wrote:At the risk of having missed it Jim, did you determine the tuning parameters of the PID beyond the SV?

Hi, Floyd -

I ultimately settled on these values:

• P = 1.3
• I = 0.06
• D = 1.5

Probably your machine is set up that way already.

For more information, Martin has written an excellent article http://coffeetime.wikidot.com/izzo-alex ... d-settings on tuning the Gicar PID in the Duetto.

Jim

LeoZ wrote:nah, it seems more fun to just toss the coffee away after i measure its temperature.

Thanks for the laugh, love it.

This is an old thread, but I can't resist on commenting this...

Marshall wrote:What is your point? The Duetto is the subject of this thread. You think with a 45-minute warmup people won't need a timer for a morning coffee for this machine? Do you think a $10 timer is an unreasonable investment?

May experience has been quite the opposite. I used to have my Brewtus II on 24/7. It is quite slow beast to wake up, as it first has to heat up the steam boiler, and next the huge brew boiler. With Duetto and a towel over the group, it takes 15-20 minutes to good stability. (I have also once tried a 10 minute shot, which tasted quite nice but had a noticeable "cold effect".)

I don't know about your morning routines, but Duetto warmup (with the towel) is fast enough for me. Timer would be a bit extra trouble, you might forget to fill the reservoir etc. I actually have bought one, but it's still in its original packaging...

Hopefully, if you forget to fill the reservoir, the machine doesn't start

Hopefully, if you forget to fill the reservoir, the machine doesn't start

No, it will instead make a beeping noise, waking people up 45 minutes too early.

Lots of great info here...however for the avg. temperatures do you have standard deviations? I'm trying to get an idea of the true temperature profile (sans average). One could have temps dancing equally from 210 to 190, and still have an average of 200...

JimG wrote:

Plot of instrashot profiles for 4 shots closely spaced (above) [Note: typo noted in legend for Shot 1. Correct average shot temp is 200.24]

NeoMatrix wrote: One could have temps dancing equally from 210 to 190, and still have an average of 200...

That would be quite a feat on an e61 and have all the ~200° points line up on the data sample interval.

The shot lines are nearly flat as are the intra/inter shot profiles