Which model Taylor is that so others can find it?

Keep in mind that when it comes to temperature measurement on espresso machines, everywhere you measure will have a different reading. And it's very difficult to predict how they will all interact to effect the temperature seen by individual coffee grounds. Yes, even the starting temperature of the grounds matters.

Of course. As a practical matter a number of us have been measuring the outside of the group of La Pavoni manual levers and similar machines and achieving consistent pulls. A good way to calibrate this is to determine the best brewing temperature of a particular coffee. Then find the measured number on the outside of the group that tastes that way. This gives a number to correct to approximate temperature in the coffee cake. If your coffee grounds are not frozen and the portafilter isn't chilled, you're going to be accurate enough for consistency.

It would be interesting to measure both group temperature and boiler temperature and then adjust (manually or computer) the boiler temperature somewhat to account for the effect the group temperature will have.

Changes in room temperature will also cause variations in final results, especially in machines with significant exposed but not thermostatically heated groups (levers, E61).

Not so much with the type of machine being discussed in this thread. You can set the PSTAT so boiler temperature cruises below desired brew temperature for everything but the coffee you brew coolest. Then use half-pumps to raise group temperature to the start temperature you want for that coffee. This allows you to brew with temperatures tuned to different coffees back to back. Generally that setting on a La Pavoni or Olympia Express Cremina is about 0.9 bar.

If you were suggesting that for an Elektra Microcasa a Leva, the idea is more salient. On that machine you can't introduce hot water to the group with half pumps, so being able to precisely set boiler temperature is more helpful.

For fun I decided to go to my local Ace, pick up a taylor Meat thermometer ($15, got gouged on the price) and then elongate the leads. The entire process, (not including the trip to Ace) took about 20 minutes. (The majority of it was fumbling with the wires to get them in the proper position for the soldering iron, so if you just decide to use wire crimps like I should have you could cut 10 minutes off the prep time...).


Materials:
thermometer (I removed the metal probe)
soldering iron + solder
speaker wire
teflon tape
electrical tape


Step 1: cute the wire!


I also cut some speaker wire, used my fingernails to strip away the coating (didn't have wire strippers handy) and soldered the joints together. I then wrapped them in electrical tape so they don't short.


In lieu of wire insulation from Radio Shack (a better long term choice I would imagine) I did the next best thing and wrapped the entire thing in teflon tape. As you can see it works quite well.



I installed it this morning against the thermoblock on the cuisinart em-200 machine in the office. Worked all day without issues. I got to teach some coworkers about temp surfing with it too.


As a side note, I noticed that someone else much earlier on this thread posted a solution for their La Pavoni using Blu-Tack. This is a very bad idea, as Blu-Tack releases toxic fumes at 93C / 200F.

Good proof of concept. So Blu Tac doesn't just melt, it emits toxic fumes!

So I've bought this thing on Ebay:
http://www.ebay.com/itm/Digital-Solar-P ... 33858cf16b
for about 10 bucks shipped.
I've taken it apart, and I imagined how to place it on my Europiccola.
I came up with a hand-shaped strip of brass which I mounted on the OVP...
here's some pics detailing what I did:



then I fastened the rear shell of the thermometer on the bracket I just built

and this is the result:


detail


I've enclosed the thermocouple in a sandwich of conductive silicone, normally used to transfer heat off of semiconductors (i.e. memory chips on high end video boards), using a cable tie


so here is how it works. Pressure in the boiler .9 bar, the machine has been purged of air. Almost 58 C.


After a small flush to heat up the group, and a couple half pulls, here's the temp: 90.4 C.

The group reaches a maximum temp of 96 C after a few more minutes and stops there, but the placement of the sensor is not ideal, being between the group and the connection to the boiler-heat transfers through this connection. A better placement would have been in front of the group, but i's FUGLY. Possibly I should factor in about 2-4 C less at the actual group. But, it's only a reference.


Brewing using Vergnano Espresso Casa.


The result, could be lots worse, I'm actually only reading the thermometer (pulled the shot at exactly 93 C) rather than going with my experience... my espresso, doing the usual dance around the machine, would have yielded more crema and a better overall taste. Need to test it for some more time, find a perfect, repeatable temperature (simply doing the reverse, brewing each time to my taste and noting the temp), until I get it right.
Of course, this bracket works for any thermometer... Not only for the one I used!
However, what do you think about the thermometer placement?

That's very well done. I like the ability to tilt the display upward with the brass tab. You've also found a convenient way to attach that tab to a nut that screws into the boiler of first version machines. Since you've asked, If I had my druthers I would fashion a clamping ring that fits on the neck of the group and attach an upturned metal mount like you've done. Displaying the readout just behind the group seems like a cleaner look. It's one I poached from the manometer placement of my Lady Duchessa.*




* Photo by Barb and Doug Garrott, taken during their restoration and used with permission.