My preferred method of measuring temperature on La Pavoni levers is at the outside of the group. This helps me consistently control shots for different coffees. There are other ways of measuring brew temperature, including using an IR thermometer at a measurable place on the group, of the coffee stream exiting the portafilter, or placing a temperature probe directly into the coffee cake, which I've done by inserting a thin wire temperature probe through a hole in a filter basket. I've even tried an experimental piston rod drilled to allow the probe without drilling to through the bottom of the piston. I'm concerned that latter approach would create a distorted measurement through retained heat in the piston. This thread is not for discussing all of those options but to show a way I've found to attach a thermometer to the group of a first generation La Pavoni manual lever. For a long time people have been describing La Pavoni levers as pre-Millennium and Millennium. There are actually three generations. The first, built between 1961 and 1974, have water heated groups that thread directly into the boiler. This is one of those first generation machines that has the challenge of finding a place to attach the thermometer because there are no group bolts to use for attachment. Once the group is fastened into the boiler on one of these it's best kept in position, and many people don't remove them for a restoration because doing so can be very difficult. The round neck of the group has a 35 mm diameter.

My solution was slightly modifying an inexpensive bicycle part, a Shimano AD15 front derailleur braze-on Adaptor 1-3/8" (34.9mm) to clamp around the group. It has a convenient hole on the side for inserting a modified Taylor Model 608 digital food thermometer. I use the portafilter gasket for an Elektra Microcasa a Leva to attach the temperature probe to the outside of the group, at the side. I had tried clamping the probe under the bracket at the group neck but found that measurement less useful than at the side of the group. Here is how it looks when completed. The machine is my 1968 La Pavoni Europiccola with the "Ultimate Europiccola" mods detailed in this thread.



The thermometer is off to the side and raised away from the boiler. This allows adequate clearance for functioning without overheating.



Here's the Shimano derailleur bracket before modification. You'll notice a protrusion near the mounting hole that I trimmed off to fit it to my La Pavoni Europiccola.



I removed the protrusion with a hacksaw, which took only a couple of minutes, since the part is made of aluminum.



The sharp edges were rounded off using a grinding wheel. The edges were further smoothed with hand files.





Here's the bracket fitted to my machine.



To prepare the thermometer, I freed the wires from the metal sheath, trimmed the sheath with a rotary tool cutting wheel and filed off the burred edges. I added electrical heat shrinking tubing to just before the measurement bead at the end of the probe. To free the wires, I had to carefully and gently pick away glue that held them in place.



Here are the spacers created from gasket material with a small leather punch. You can see the heat shrink tubing to the left.



To further steady the thermometer in its mounting hole, I may use a dab of JB Weld epoxy, but for now the good news is this works, and the parts aren't expensive. I will also need to calibrate external group heat to brewing. So far a first shot with a dark roast coffee that likes 175°F/79C worked well, even though the outside group measurement increased to 188°F. This means it was sinking heat and cooling brew temperature in the coffee cake. As I've written in earlier threads on adding thermometry to a La Pavoni, the outside group temperature is for calibration and is not equivalent to actual brew temperature.