La Pavoni mods

The design of the La Pavoni Europiccola has remained fundamentally unchanged since its debut nearly 60 years ago. Improvements such as the addition of a pressurestat, or the anti-vacuum safety valve, the adoption of slightly larger filters or the addition of a polysulfone sleeve in the grouphead have been made over the years, but none of this has been enough to restrain the most enthusiastic and demanding fans. As a matter of fact, there are many modifications that enthusiasts from all over the world have applied to this machine to improve its performance, solve problems or just for aesthetic reasons. Some modifications are very simple but at the same time effective, others are more invasive such as the addition of a PID to regulate the temperature of the boiler. Among the many, one of the first and probably best known is the one developed by Tije de Jong, let's see what it is.

Grouphead heatsink - Tije de Jong
In 2011, Tije bought a La Pavoni Professional pre-millenium and promptly realised that the unit tends to rapidly overheat. Solutions like wrapping the grouphead in a wet cloth or plunging it into a bowl of cold water seemed impractical. In his workshop, he fortuitously found a piece of an aluminum heatsink that he decided to bend and shape to wrap around the grouphead of his Pavoni. Without carrying out any sophisticated tests, Tije soon realised that this modification enabled him to extract several espressos at the right temperature without having to worry about cooling the grouphead each time.

A few months later, on a Dutch forum dedicated to the world of coffee, he happened to read about many enthusiasts who were struggling with the same problem he had solved with the heatsink a few months earlier. He posted pictures to show his solution and one day later he was contacted by a great coffee enthusiast named Frans Goddijn who asked him for a heatsink for his Pavoni. Frans, once mounted the heatsink performs a series of tests and verifies that indeed this modification is extremely efficient and makes the machine very stable in terms of extraction temperature. Since 2012, Tije has built many heatsinks on demand and shipped them to every corner of the world. 

Tije’s heatsink

LCD thermometer for the grouphead
Every coffee has its own ideal extraction temperature, which is usually between 88 and 94°C, and if you try to extract it at a higher temperature you risk burning it or over-extracting it, vice versa, at a lower temperature you under-extract it. The temperature of the water in the boiler, on the other hand, is much higher, at around 120°C, but as it travels to the grouphead it cools down because the group has a lower temperature. It is therefore clear that the temperature of the grouphead is crucial for cooling the water coming from the boiler and therefore important for the correct extraction of espresso, which is why many users connect the probe of an LCD thermometer directly to it. In this way, temperature fluctuations are constantly monitored and extracting an espresso to its full potential becomes a much easier task.

Grouphead conversion from steam-heated to water-heated - Dan Metcalf
After moving to Japan, Dan Metcalf used to extract from 5 to 8 espressos in a row with his 1984 Pavoni pre-millennium. Like for Tije, he too found the overheating of the grouphead a problem that he would remedy by dipping it in a cup of cold water. Finding this method extremely inconvenient and at the same time noticing that the first generation Pavonis (up to 1975) had a less evident overheating of the group, he decided to study the differences. He realised that while the very first generation of Pavoni was equipped with a water-heated grouphead, the second generation had a steam-heated group.

Armed with patience and good will, he devised a modification using the grouphead cap of the current Pavoni milleniums and by making a hole on the "L" shaped pipe that connects the boiler to the group. In this way, the group's heating system changes from steam to water. The temperature stability obtained is therefore much better than the original one. This modification has been appreciated and applied by thousands of users all over the world.

Isolator - Bong Juachon
The latest innovation to address the problem of cooling the grouphead when extracting several consecutive espressos is Bong's invention of the homonymous isolator. This invention bases its effectiveness on two different aspects:

• It breaks the conduction of heat from the boiler to the group as, once the insulator is mounted, the group and boiler are separated by a spacer of athermic material.

• At the same time, it performs a "Metcalf conversion" of the grouphead from steam-heated to water-heated. 

It is therefore easy to see that the isolator is highly effective in solving this atavistic problem and is also easy to implement. For this improvement also, there are many enthusiasts who could not resist upgrading the temperature management of the grouphead with a very minimal aesthetic impact.

Once the isolator has been fitted, the temperature of the group rises much slower compared to the same machine without the isolator, but this should not be a cause for concern as it is possible to raise the temperature of the group quickly and precisely using the "dry pumps” method. Another peculiarity of this modification is that it makes it possible to increase (by operating on the pressurestat) the pressure in the boiler, thus improving the performance of the steam wand for frothing the milk.

Pressure Profiling Kit (PPK)

Hybrid Smart Espresso Profiler, with analogue gauge and electronic module

In recent years, the use of a Pressure Profiling Kit, in other words, a kit for profiling the pressure curve during coffee extraction, has become increasingly popular. This is a modification which, through the use of a piston and shaft with a longitudinal hole and a pressure gauge mounted on top, allows the pressure inside the grouphead to be read in real time both during the pre-infusion phase and throughout the extraction of the espresso.

The first documented evidence of a kit of this type dates back to a post on the famous American forum Home-Barista in 2006, authored by a user who responds to the name of John Nanci, but commercially it has been made available since about 2015 by the Hungarian company "Naked Portafilter" of Gábor Laczkó. This type of modification is very much in demand and appreciated also as a consequence of the Third Wave Coffee movement. The reason for this is easily explained: since the classic espresso has evolved and baristas and coffee lovers have started to use quality coffee beans and not only dark roasts but also medium-light or even light roasts, the control of the pre-infusion and extraction pressure has become a very important variable to consider and to which all professionals pay a lot of attention. It is enough to think how companies such as La Marzocco, Slayer and Decent Espresso have tried to replicate the extraction profile of lever machines in an electronic / informatics way.

A further step forward in the world of pressure profiling for La Pavoni machines has been made thanks to the innovative system called "Smart Espresso Profiler", designed by Gábor Laczkó and Csanády Miklós and distributed by "Naked Portafilter". It is an electronic sensor that replaces (or if you wish, goes alongside) the classic pressure gauge and which, via an app for smartphones and Bluetooth technology, allows the user to view and record the entire extraction curve. This recording can then be used, for example, to replicate the same type of extraction on other lever or pump machines such as those mentioned above. 

Using a pressure profiling kit, it is interesting to be able to analyse the extraction curve of a coffee and notice how the same coffee, extracted with different pressures, can develop different aromas, body and intensity of acidity and sweetness. 

Pressure profiling gauge screwed into the grouphead - Clay Lowe
During his day-to-day experience of using lever machines, Clay had the opportunity to try 2 different pressure profiling kits that, although they did their job, did not particularly excite him. One kit, for example, was not very solid in the part that connects the fork of the lever to the piston shaft, while another kit from a different manufacturer, although it solved the problem just mentioned, had a way of connecting the pressure gauge to the piston shaft that was not very elegant.

Another aspect that he didn't like was the position of the pressure gauge itself, which was not in eye line during espresso extraction. So, without thinking twice about it, Clay drilled a 1,5 mm diameter hole on the side of the grouphead and then literally screwed a pressure gauge into it at a 45 degree angle. In this way, even with a pressure profiling gauge, the solidity of the lever is not compromised and during extraction, just by moving his eyes he could look at the cup, the mirror positioned near the base that showed him how the coffee flowed from the bottomless portafilter or the pressure gauge.

Still experimenting with pressure profiling kits, Clay thought of a way to make this modification less intrusive and perhaps easily removable from one extraction to another, something easy to disassemble and reassemble and that could be used on multiple machines. He therefore thought of moving the position of the profiling gauge from the grouphead to the portafilter as follows: he took a portafilter with sufficiently thick walls, he drilled a hole on one side and then screwed a gauge into it. He then drilled a hole about 1 mm in diameter in the wall of the filter (just below the upper edge) and positioned two very thin o-rings, one under the upper edge of the filter (where it rests on the portafilter) and one on the lower edge inside the portafilter, where he had previously carved a groove around the entire perimeter.

In this way, whenever he wants to monitor the pressure curve of the extraction he uses this modified portafilter, while when he does not want to, he can just use a classic portafilter. As a result, the aesthetic of the machine is not affected and the same system can be used on other models with compatible portafilters.

Pressure profiling gauge mounted on the portafilter

Metal sleeve for post-millennium models - Tudor Si Tabita Petriman (Coffee Sensor)
One of the things that many owners of post-millennium machines don't like is the fact that inside the grouphead, the pre-infusion and extraction of the espresso take place in a polysulfone (PSU) sleeve rather than a metal one. Although this material is safe for food use and has been introduced to ensure greater temperature stability, what is not appreciated is the idea of a material that tends to become brittle over the years.

About a year ago, Tudor Si Tabita Petriman, owner of Coffee Sensor, a manufacturer of coffee machine accessories, decided to design and build a replacement for the PSU sleeve in two different versions: stainless steel and brass, giving the possibility of having one less part that is subject to wear and possible damage. Besides this, PSU sleeves cannot be as precise in their construction as the precision obtained using lathes and CNC technology, which is why their internal diameters are often not as regular, affecting the movement smoothness of the piston.

After about a year in the market, several tests were carried out on both the stainless steel and brass sleeves and, in particular from a thermal point of view, there was no deterioration in performance compared to the PSU version, maintaining the same extraction quality, perhaps at the expense of a slightly longer initial heating time.

Lever fulcrum bearing - Imsung Yoo
After all the attention dedicated to the grouphead, there are also those who have instead concentrated on the fluidity of the lever. This is the case of Imsung Yoo, who decided to make the lever stroke of his Europiccola smoother by replacing the standard factory roller with three aligned bearings and two rollers.

A little later, Tije de Jong further improved this modification by using a single bearing of the "NK 6 / 12 TN" type to replace the 3 parallel bearings used by Imsung, making this modification even simpler and more functional.

Custom bases - Clay Lowe, Steven Gilchrist
Some users do not particularly like the way the boiler bends forward during extractions that are particularly demanding in terms of physical effort. For this reason, or even purely for the desire to personalise their lever machine, they replace the original base with a base built according to their own taste and creativity.

Custom base by Clay Lowe on the left and by Steven Gilchrist on the right

Clay Lowe, for example, built a base made of aluminium, stainless steel and plexiglass for his pre-millenium using tools commonly found in the home and online services for custom cutting of steel and prefabricated parts. The base as made by Clay is extremely solid, even with extractions at the highest pressures the boiler doesn't flex at all, it makes the machine more stable due to its increased length and weight and the design is totally open source.

Steven, like Clay, also wanted a larger, more stable base for his Pavoni but decided to swap it for the already existing one of the Riviera Zacconi. The base of the Riviera, however, has a hole for the boiler with a larger diameter than that of the Pavoni, so there was a compatibility issue to resolve. A flange was therefore designed in CAD to act as an adaptor and once the design was made, Steven printed it out on paper so he could check the accuracy of the measurements and then had it laser cut out of stainless steel.

Single hole steam wand tip
In order to be able to perform a good latte art, it is essential to froth the milk correctly so as to obtain that fine-textured micro-foam. To do this, however, you need good technique and excellent control of the vortex which, as the seconds pass, sucks in the bubbles and makes the milk extremely silky. Although it is possible, many people find it difficult to achieve this level of control with the supplied three-hole steam tip and so it is often replaced with a one hole tip. This is in fact a very simple modification as the nozzle is only screwed onto the steam wand.

A special mention should be made about the steam tip designed by Bong Juachon and recently marketed by Tudor Si Tabita Petriman. This tip may partly resemble the one made by Katsura Kawate, which we talked about in the last issue, in that its characteristic length means that the joint where it connects to the rest of the steam wand does not end up in the milk and is therefore easier to clean; but it has a very interesting internal structure. Most traditional steam tips in fact, only have holes of a certain size at the extremity and simply force the steam to pass through them before being released into the milk. This particular steam tip, on the other hand, does not only have a simple hole at the end, but the steam is funnelled into a small cavity for several centimetres before it can escape, somewhat in the same way as a bullet does inside the barrel of a rifle, making for a more regular and concentrated flow.

Still on the subject of particular steam tips, mention should also be made of the one produced by Douglas Weber (Weber Workshops), which has a proprietary system that allows you to choose the type of opening and therefore of steam emitted depending on the use and also on the pressure set in the boiler of your machine.

Coffee Sensor long single hole steam tip

Steam wand on / off joystick - Bong Juachon / Coffee Sensor
Some users do not really like the knob to activate the steam wand which needs to be turned several times to guarantee maximum power and vice versa to be closed completely. For this purpose, a kit called B-Push has been created that allows to eliminate the factory steam knob and have a joystick that opens and closes the steam simply by moving it up or down.

The advantages, as already mentioned, are the ease and speed of use, and the reduced possibility of overheating the milk during the frothing phase since you can turn off the steam with a single and quick gesture.

Precision filters – IMS
Finally, the latter are part of the accessories that, together with the thermometer to monitor the temperature of the group and the coffee grinder, greatly influence and modify the quality of the espresso in the cup.

Precision filters have extremely precise micro-holes and undergo a chemical electro-polishing process that makes their surface more rust-proof by removing iron oxides and also removing the micro burrs inside the holes. This is not only for aesthetic purposes but also for functional ones: the filters become more water-repellent and easier to clean, and the holes do not get clogged by ground coffee particles, allowing greater passage of the oils present in the coffee.

They are available in different sizes so that the extraction can be optimised according to the type of coffee and the roast level used. For example, with light roasts, it is usually necessary to increase the dosage and therefore a larger filter is a mandatory choice. In this regard, two clarifications are necessary regarding the use of the 20 grams filter for post-milleniums and the 18 grams filter for pre-milleniums. For the post-millenium, the current La Pavoni portafilters have been updated by the mother company so as to be able to use the 20 grams filters that have a considerable depth; the more dated bottomless portafilters instead, require a modification to be made with a lathe. On the other hand, for pre-millenium filters, the old bottomless portafilters all need to be modified with a lathe; if, however, a compatible portafilter with a straight bottom wall is used, then this problem does not persist.