La San Marco single group lever

Posted on January 7th, 2016

converted La San Marco single group lever

Dual boiler, dual PID commercial lever beast!

This beast started out life as a La San Marco 85 series, single group volumetric heat exchanger. I bought it last year as a fixer upper, the boiler was over filling and it needed a general going over. 9 months or so later and it’s a very different machine to the one that came in!

Turns out the over filling problem was a fractured heat exchanger, so that ruled out keeping the machine conventional – the heat exchanger would have to be decommissioned, capped off and become part of the steam boiler volume – I didn’t like the chances of a successful repair.

At that point it became a total strip down, and while I had the bare chassis on the bench, I started playing around with the possibility of fitting a lever group that I had spare. With an extra cross member in the chassis, it would totally work! So, off to see my mate Gonz who worked his magic and welded in a cross piece to take half the group flange. The group was already fitted with cartridge heaters, from back in the days of the Quick Mill Achille testing with Talk Coffee, so why not take advantage of that? Then, why not add some extra precision with a dedicated brew boiler as well? Yep, it would fit with a bit of wrangling. I also adapted a small volume heat exchanger into the existing steam boiler to provide pre-heated water to the brew boiler. Serious overkill at this point but why the heck not?!

So, this ended up being the most advanced lever machine I’ve built to date, with a PID controlling the group and a PID controlling a dedicated brew boiler just behind it, temperature control is phenomenal. By tweaking the two set points, you can even control the shape of the traditional lever temperature profile.

The original boiler is slightly under-specced at 1700W, but it allows the total machine wattage to stay at approx. 10 amp draw, with 600W in the brew boiler and 200 in the group. It takes a while to reach 1.5 bar, the group is hot well before then – but is ready to go after 25 min approx. and steam pressure is never an issue due to the huge volume for a single group, and added insulation.

It’s plumbed in only, as the line pressure primes the brewing circuit and is used for pre-infusion. The spring installed in the group (new of course) generates 10 bar peak pressure. It’s a delight to use and pulls wonderful shots. I’m mad to sell it, but that’s the reality of running a business, I can’t hang on to everything!

Summary of work done:

solved issue with heat exchanger crack
entirely new brewing system – group, boiler, pre-heater, PID control X2.
new autofill controller, SSRs, wiring as required.
rebuilt all existing valves, plumbing.
powdercoat exterior panels in electric blue hammertone (bold, I know, but it looks stunning!)

It’s probably the most advanced lever machine in the world, in terms of temperature control (at the time of writing – 2016). Offers will be considered. I am in the process of finalising fitment of the front panel, as it was never intended to cover a lever group. Once that’s done she’s ready to go, will not take me long!

Andy’s Londinium

Posted on August 9th, 2013

Andy’s Londinium

Domestic lever dual boiler conversion

The Londinium Espresso L1 is a new addition to the market for single group lever machines intended for domestic use. There has been a recent resurgence of interest in lever espresso machines, as we are finding out more about the subject of ‘pressure profiling’, or controlling the water pressure applied to the coffee puck at different stages of the extraction.

Andy was a little disappointed with both the fit and finish and the temperature stability of the machine, so we decided to see what we could do to take it to the next level. Without going into too much detail, the Londinium uses a fairly uncommon thermosyphon arrangement to get enough heat into the massive group. After gathering some data on how the thermosyphon functions and comparing this with other user’s data from around the world, it appears that there are conditions that can alter it’s performance, resulting in low group temperatures and sour shots.

We considered a few options, one of which was reconfiguring the thermosyphon into a true heat exchanger that operated from mains water pressure instead of the built-in tank, but Andy was keen to retain the ability to run from tank. This meant a drastic alteration of how the group was heated, and the fabrication of a separate brewing boiler to tightly control the water temperature at the group. Luckily, the internal construction meant that the original boiler could be retained and minimal alterations to the layout were required.

The end result is a traditional lever machine that has all the inherent temperature controls of a modern dual boiler machine. Changing the set temperature of the brew boiler controller results in a quick change in the idle temperature of the group itself, which governs the temperature profile of the shot.

We were also able to address a few of the annoyances with machine fit and finish, such as ease of emptying the drip tray, placement of switches and internal venting of the anti-vacuum valve.

Andy is stoked, and the proud owner of what may be the most technically advanced lever machine in the world.

Custom Salda

Posted on September 21st, 2012

Custom Salda

Single boiler domestic machine

I bought this little Salda for $10 at a garage sale, knowing it would be a good little machine with a service and a few minor improvements.

As standard, single boiler machines including the Rancilio Silvia, Gaggia Classic, Lelit, Nemox, Imat, Quaha and others are perfectly capable of making good espresso though with a few downsides, one of which is a huge variance in boiler water temperature due to their very simple thermostats. This can be compensated for in a few ways, one popular option being to retrofit a PID controller to help regulate boiler temperature more precisely, which is one key ingredient to making consistently good espresso.

This is a rather expensive and complicated option (although PID hardware itself is not costly these days – it’s the installation and calibration that can be tricky), and a simpler, more cost-effective modification can be to simply fit a digital thermometer to the boiler giving the user a visual indication of the boiler temperature, which can then be used to time the start of the espresso extraction for the best results. This is known as Temperature Surfing.

Improvements included:

Replacing the original Saeco-type pressurised portafilter and group collar with a 57mm non-pressurised Lelit type, with naked conversion
Brew water pre-heating via a simple tube that wraps around the boiler to improve temperature stability
Digital temperature display via thermocouple fitted to brass boiler
Conversion to ball-joint steam wand including custom single-hole steam tip
Brew pressure gauge fitted between 3-way solenoid and group outlet to read true extraction pressure
Kill switch fitted to pump to enable low pressure pre-infusion
Custom aluminium handles for steam valve / portafilter, custom Huon Pine matching tamper

I ended up taking things a bit further than I’d initially planned, but I reckon this is now the best little single boiler machine around, and makes killer shots with a bit of careful attention to the brewing temperature and pressure. As it’s so simple and small, this is the perfect machine to chuck in the boot with a hand grinder for a weekend away.

Improvements and modifications

Posted on September 21st, 2012

Improvements and modifications

Getting the best from your gear

While most domestic and commercial espresso equipment on the market is capable of achieving excellent results, there are occasions where better performance can be gained from making a few simple internal modifications. Through monitoring how the machine is behaving, we’d be able to assess what, if anything, could be gained in terms of temperature stability at the group or other usability improvements eg. better steam pressure, quicker recovery time etc. If you’ve got something in mind, I can tell you whether it’s going to A. give you the result you want, and B. remain safe and cost effective.

Thermosyphon Restrictors

In most cases, excessive group temperatures in traditional heat-exchanger machines can be controlled through the addition of a thermosyphon restrictor (a small disc with a precisely sized opening, placed into the heat exchanger) that is tuned to the particular temperature that you want to achieve. This allows you to lower the temperature at the group without losing steam pressure, and negating the need for a cooling flush. It’s a very simple but significant upgrade for most domestic E61-group machines that run hot – associated with burnt or bitter flavours in espresso and steam/spluttering from the group when the pump is activated.

Temperature studies, PID control and boiler upgrades

For the ultimate temperature control, some machines may benefit from replacing stock thermostats or pressurestats with modern PID hardware. This often has a dual benefit in terms of easy temperature adjustability, and long term reliability as digital controllers and associated devices have no moving parts.

Usability improvements

The list of possibilities are almost endless. If you’d like to improve your existing machine rather than upgrading, give me a call and we’ll see what can be done. Some suggestions to get you thinking:

Swapping steam and hot water wand locations
Upgrade to lever-activated steam valve or cool-touch wands
Custom steam tips for more usable steaming
Two-stage pre-infusion switch for semi-automatic solenoid groups
Upgraded heating element control system incorporating solid state relays for greater reliability
Adding auto-fill controllers to older manual fill machines
Plumb-in conversions for tank machines