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!

Linea Mini paddle modification

Posted on January 6th, 2016

La Marzocco Linea Mini paddle modification

enabling the true function of the Manual Paddle

As usual, there are aspects of any piece of equipment that can be improved. My main gripe with the Linea Mini is that as standard, the paddle switch is not a ‘real’ paddle switch.

Let me explain – the original MP ‘mechanical paddle’ group is much loved by baristas for the control it allows over the pre-infusion phase of espresso brewing. The mechanical nature of the group allows the water flow to be turned on first at a lower, or ‘line’ pressure – this is simply the water pressure present in the mains and through the boiler/group, usually around 3 Bar. When the paddle reaches the end of it’s travel, the pump is engaged, and full brewing pressure (around 9 bar) is applied to the coffee. This two stage operation allows a skilled barista to perfect each shot by allowing the most critical first stage, where we want an even saturation of the coffee bed, to happen at a lower pressure. This improves the chances of the coffee puck saturating evenly, giving us a tastier shot.

So, a Mechanical Paddle group is a good thing in terms of control, but, being mechanical, there is a down side. It’s relatively complex to make and thus expensive, and, requires fairly regular replacement of o-ring seals. La Marzocco chose to fit a paddle switch to the Linea Mini, but the important distinction here is that it does not operate a mechanical valve, but a single microswitch which engages the water flow and the pump, practically simultaneously. Thus, the ethos of the paddle is lost because there is no first stage. It doesn’t matter how you move it, quickly or slowly, the result is the same. All this is not to say that it doesn’t work – clearly it does, and well, we just lose out on control over the infusion process. Perhaps La Marzocco chose this for reasons of simplicity – my argument would be all well and good, but if there is a paddle switch present, the expectation is that it works like a real one.

Well, we can make that happen! On the pump outlet I’ve added an extra solenoid with an adjustable needle valve, that is switched on as soon as the paddle is out of it’s stop position. This allows the first stage of the paddle’s movement to replicate the line pressure stage of a mechanical paddle group. In fact, the pressure can be set internally by adjusting the needle valve setting to give whatever pressure is desired for the pre-infusion phase.

Then when the standard microswitch is engaged mid-way through the travel, the bypass solenoid is switched off and the pump comes to full pressure. In addition I’ve added a spring loaded pre-infusion cylinder to the group to further soften out the pressure ramp-up and decline. The group pressure control ends up being a hybrid of Slayer, Kees van der Westen Speedster and La Marzocco Mechanical Paddle – with the best of all worlds. All electric, no seals to replace and fully adjustable. I’m very happy with the result!

Summary of the modification:

two-stage operation with adjustable ‘line’ pressure
spring-loaded chamber further smooths out pressure ramp-up
All electric, no seals to wear out
works in tank mode or plumbed in, with adjustment of needle valve accordingly
hybrid of Slayer, Speedster and La Marzocco pre-infusion systems
paddle action refined for perfect smoothness and feel

At this stage the installed modification is only available for machines brought to my workshop, and there are no plans to distribute a kit as modifications of factory parts, plumbing and electrical connections are required. If you are confident to handle this work as a DIY install, please contact me for pricing and availability. Alternatively you could contact a trusted technician local to you to perform the install work with my instructions. The modification is available for both 230V and 110V machines.

SOLD – Kees van der Westen Mistral

Posted on June 16th, 2015

Mistral machine no. 32

Kees van der Westen

cm20150603_Kees-van-der-westen---Mistral-Duette-side-V1

Complete nuts and bolts rebuild – new legs, chassis powdercoat, and full re-polish of panels. Every gasket and valve replaced. Over a year part time on the project at this stage!
New coffee boiler.
Insulated steam boiler.
A total of three PIDs, one for the coffee boiler and one per group cap via cartridge elements. Steam is pstat/SSR.
Power is 25 Amp single phase, about 5 amps more than original.
Steam valves converted to lever type, one lock-on direction forward and momentary purge backward. Valve bodies are Nuova Simonelli adapted and feature a LM anti-vac valve on each wand.
Custom paddle switch – functionally the same as Marzocco MP group, two stage operation, but electrical rather than mechanical so there are no seals to change.
Chronos key pads for shot clock, volumetrics on both groups with a manually controllable preinfusion function. Use either touchpad or manual paddle at any time. I find I like to flush with the paddle and pour shots via the touchpad.
Custom made dispersion block in POM-C (same as current Speedster setup) for cleaning ease, temp stability.

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.

James’ San Marino

Posted on December 2nd, 2012

James’ San Marino

Commercial single-group machine

I can’t think of a machine with a worse reputation in the industry than the San Marino but I kind of like them, and machines made by CMA in general (wega, astoria etc). They’re solid, no-nonsense commercial workhorses that may not be sophisticated, but dangit they get the job done. James loves his, and it’s been on coffee duty at his studio for many years. When the element gave up, we decided a thorough overhaul was in order.

Predictably, I went a bit nuts and decided to see how well I could make it work. The main drawback with San Marinos is that they lack a thermosyphon – the group is bolted to the boiler and can drastically overheat. The solution in this case is to inject cold water deeper into the heat-exchanger to lessen the need for a hot flush right at the start of an extraction. I also wanted to control the flow rate from the group, which was way too high, by fitting a restrictor to the inlet side of the group solenoid. The finishing touch, apart from a thorough recondition of all valves, sight glass, boiler valves etc, was to add a dual rocker switch for the solenoid and pump – allowing manual pre-infusion control via mains pressure.

Summary of improvements:

Brew water temperature down from +98 degrees c. to 92-94 after a 30 ml flush
Flow rate down to 600 ml per min from the group for controlled extractions
variable mains pre-infusion time via independent switching of the solenoid and pump

I was pretty stoked, and James was too –

Many thanks for your all your efforts in resurrecting my San Marino. This machine is at its best and has never worked in this manner ever! As you can see by the lateness of this email – you may guess that I’ve had a couple of long blacks.

Job done!

Aaron’s tamper

Posted on November 7th, 2012

Aaron’s tamper

Custom fit Coffeelab tamper

One often-overlooked ingredient to good espresso preparation at home is use of a quality tamper. In that regard, it’s hard to go past the Australian-designed and made Coffeelab, it really is a thing of beauty – the materials, design and feel of the finished object are top notch.

The crucial thing that is hard to achieve with an off-the-shelf tamper is a good fit to the basket to ensure an even tamp, and in this case Aaron was looking to improve the match of his existing base to the 54.5mm baskets of his La Spaziale. I was able to help by sourcing a new 58mm base directly from Coffeelab, and re-machining the diameter to provide an exact fit.

The result was a perfect fit, without changing the ergonomics or appearance of a design that Aaron already loved. Sweet!

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.

Custom Robur

Posted on September 21st, 2012

Custom Robur

Commercial conical grinder

I picked up this grinder as a fixer-upper, there was a sad story from the previous owner which involved attempting to grind the stainless steel bolt that holds down the central burr blade. Roburs have big strong motors and reduction gearboxes, so this was enough to bend the shaft that holds the burr, leaving a non-functional grinder making very nasty crunchy noises.

To fix it, the entire grinder was disassembled and the gearbox shaft painstakingly straightened and re-machined to perfect alignment. It would have been far easier to replace that part, but they are not stocked in Australia so a replacement was very costly and months away by boat.

While I was there, I did the following mods:

Polished grinding chamber for lower retention of ground coffee
Stripped back and polished aluminium body
New small-capacity hopper from perspex and machined delrin
Dial indicator on adjustment collar to show grind size in 100ths of a m/m
Doser modified to sweep clean
auto-start and auto-stop switches removed
new adjuster lever in aluminium and matching doser lid in delrin

This is now my workshop grinder, and I’m pleased with the mods. The dial indicator makes it really easy to swap back and forth between filter and espresso grinds with a high degree of precision.

Microcimbali restoration

Posted on September 21st, 2012

Microcimbali restoration

Vintage domestic lever machine

This was a good example of the sort of horrible condition that many vintage domestic machines imported from Italy are in. Plentiful rust, corrosion, scale, damaged chrome, perished insulation, seals, etc etc. Beware the optimistic eBay description! However, the appeal of these vintage lever machines is justified – once restored, they really are functioning design icons of a bygone era.

Luckily, the most important parts of the machine were fixable. The worst case scenario is that the element filament or insulation is damaged, meaning a costly one-off custom element has to be made. Luckily this was not the case and repairing the element just involved re-sealing the terminals with high-temperature insulation compound.

Further work included:

Repairing hole in cast aluminium boiler by drilling out and plugging internally with new material
Drilling out and re-threading damaged mounting points on boiler casting
Re-wiring with modern silicone insulated cable
Replacing all perished seals with OEM or custom made versions
Polishing exterior surfaces and fittings

These old lever machines fascinate me, and I love working on them. They are always a challenge, but there’s nothing more satisfying than getting a perfect shot out of a machine you’ve restored, and it’s now an asset the new owner will enjoy for many years to come.

Nic’s Bo-Ema

Posted on September 21st, 2012

Nic’s Bo-Ema

Vintage two-group lever machine

This beautiful lever dates from 1964, and represents both Australia’s manufacturing and cultural history as it was in Sydney in the 60’s. Espresso bars were gaining popularity, and at that stage the only commercial machines available had to be individually imported from Italy, or brought over as cargo by emigrating families. The story goes that two enterprising continental chaps named Bordignon and Emer got together in their Revesby factory, which at that time churned out terrazzo polishing machines, and decided to have a go at producing a machine locally. The result found it’s way into a few choice locations, and Bo-Ema still produce espresso machines in Sydney, though the company has changed hands a few times, and modern bo-ema’s are not exactly a thing of beauty.

The current owner wanted to give it a thorough restoration to working condition while preserving the patina of a lifetime of hard work.

With most restorations, the machine is completely stripped down to it’s component parts, everything is meticulously cleaned, polished and reassembled with new parts where necessary, then tested and tested some more. In some cases there are hundreds of hours of labour involved, particularly if parts that are no longer available have to be made – in this case the seals for all the valves had to be custom wound from a mixture of oldschool hemp fibre and modern PTFE.

Other major jobs included:

Custom made powdercoated chassis brace including new feet to replace the missing originals
Drilling out rusted steel studs from boiler flange and replacing with stainless/brass hardware
Replacing rusted group springs to achieve full 10 bar pressure
Complete re-wire with modern pressurestat and thermal cutout for safety and reliability
Hand polishing valve bodies, lever handles, fittings

The result was a machine that is working better than when it left the factory 50 years ago – there’s nothing quite like a commercial lever machine and Nic is lucky enough to have one that is a significant part of Australian espresso history.