Five Senses Coffee Blog

Opening shots

Project X

This project is really coming together. For the benefit  of anyone visiting for the first time, I am nearing the end of the construction phase,  combining the complete front boiler assembly from the world’s best commercial coffee machine into the chassis of an Isomac La Mondiale. The result will be an unassumingly compact dual boiler home espresso machine that can boast specifications only found in top of the range commercial machines.  So, after wiring up the Solid State Relays (SSR’s) that will power the brew and steam elements, there is nothing preventing me switching on and pulling some test shots.

The Hybrid Coffee Machine from Five Senses Coffee on Vimeo.

These first shots were excellent. To be honest, I was quite surprised with the stability the low cost PID controller is achieving, with only a small amount of tuning. There is no pre-heating of the brew water, the steam boiler is not insulated and the covers are off.  Initial observations are that there is no more that a deviation (drop) of 1 degree Fahrenheit over the duration of the shot (+/- 1 digit). The PID display only allows a minimum resolution of 1 deg, including whilst adjusting the offsets, a significant weakness.

There is a lot of work ahead perfecting and fine tuning the machine yet.  A pre-infusion timer, a better quality PID and a pre-heating system (low power thermoblock????) are all on my to-do list.

It would also be nice to have a name for it…

~richard

A PID, SSRs and lots of Wire.

Cutting holes in the front panel of a stainless steel coffee machine is always a bit nerve wracking. I  hardly slipped at all in the end.  About 2 hours with a flat file and I had a nice rectangular hole of the correct size for my PID controller.

I had considered locating the PID out of sight underneath the machine and facing rearward or even under the drip tray. My thinking was that this would, with one obvious exception, preserve the standard look of the Isomac La Mondiale. (one of my stated aims) In the end though, its got to be all about the coffee and when it comes to coffee, temperature is king. We must have easy access to the brew boiler temperature display so, in front it is.

The PID and the Steam boiler pressure-stat will both drive its own heavy duty Solid State relay (SSR). The SSRs will in turn will switch the higher current to the elements themselves. I have bolted the SSRs to the underside of the base plate of the machine which will act as a heat sink of sorts though these SSRs will be operating at about 25% of their capacity so I’m not imagining they will get very hot.

The boiler level is contoled by the original Isomac Auto Filling controller. I actually had it all connected up as a test and I got some great steam happening last week.

The brew pump will be controlled by a small relay also bolted to the bottom of the base panel.  Since the steam boiler will fill under mains pressure, you may be wondering why the machines pump could not just have been switched by the Synesso Cyncra brew group switches. The reason is…… I am going to integrate a pre-infusion timer as found in the latest Synesso Hydra (as an option). The timer will take over control of the brew pump via the relay.

The current job is just wiring everything up. It looks like a birds nest at the moment but it will tidy up nicely. I’ve used color coding of the different funtions etc.  All wire is heat resistant of course.

`richard

Steam boiler plumbing.

Its time to install the steam boiler plumbing connections. The Isomac steam boiler has four 1/4″  holes along its top. We actually need to make six connections so I had to add a couple of  Tee connectors and mount the  Vacuum breaker, Safety Valve and Steam Pressure Gauge off the one point. The Water level Probe, Pressure-stat and Steam Valve Outlet fill up the remaining three positions.  The other items are the water filling and the hot water outlet tubes which are both on the left side of the boiler, below the waterline.  The lack of space above the boiler means that I had to make extension tubes to offset and lower level of the valves and pressure-stat before they would fit under the top cover of the machine.  I just need to add some electrics now and will will have some steam. ~richard

Mounting the steam boiler.

The steam boiler is being held in place by a bracket at each end that will  support the weight of the boiler vessel and its contents.  In the Isomac the same boiler was supported mostly by the various pipes that connected it to the machine. The largest of these pipes, the ones that connected the boiler to the E61 group are not being used in my machine so I have had to make some brackets myself.

The RHS bracket is bolted to the upper two brew element mounting bolts and encircles the element flange on the steam boiler. It has a bend in it to align the two boilers in the centre of the machine.  I decided make the LHS steam boiler support bracket a  part of a heat shield I wanted to insert between the two boilers and the brew pump.  The pipes and fittings to connect up the water supply and steam valves will help keep everything firmly in place once fitted.

All of the major mechanical assemblies are now in place. The next step will be to install the rest of the plumbing and do some pressure testing.  ~richard

Brew system plumbing.

Having installed the brew boiler and brew pump we can now install some tubing to connect it all together. The copper tube from the brew boiler inlet to the pump output should be pretty straight forward but I can foresee a possible problem with the temperature stability of the brew system,  if we don’t include a method of adequately preheating the incoming water. I am thinking that the temperature of the water in the relatively low volume brew boiler will be significantly effected by incoming water with a large temperature differential. I will leave it connect directly for now but I’m sure we will need to revisit this once I can measure the machines temperature stability. I think simply using the heat exchanger in the steam boiler as a pre-heater will probably cause the opposite problem with the group overheating.  I’m going for a very high level of temperature stability from this machine so this will need a good solution. Ideas anyone ?

From the above images you can see that I’ve installed the all important expansion valve and brew pressure gauge on a Tee off the pump output. The pump supply side has a one way valve inline with the supply water inlet tube that runs to the base plate where it pokes through to a standard 3/8 hose elbow connection. The supply tube also connects to the steam boiler filling soliniod through another tee.  Its starting to look like a coffee machine. ~ richard muhl

Fitting the front boiler.

The first step is to totally strip everything out of a brand spanking new Isomac La Mondiale.  To install the Synesso brew boiler we will need to cut a 90mm wide section from the stainless steel front panel. It would be great to just make it a nice neat square  for only the neck of the group to poke out through. Unfortunately I am also going to have to allow access to the brew soliniod positioned underneath in case it ever needs replacing.  I will need to come up with a snazzy cover to screw over the brew valve access later.

TheSynesso brew boiler itself is mounted on a plate that is positioned to cover the holes left by the removed E61 group and leave 13cm from the group collar to the drain tray.  With the brew boiler in place there is no longer enough clearance for the duel pressure gauge to be installed.  To resolve this I have had to unsolder the upper (steam pressure) capillary tube and cut off about 9mm of the gauge body and about 6mm of the bracket holding screws. (see image) After re-soldering the upper tube the gauge now clears the brew boiler.

Next is the mounting of the brew pump and motor.  One side of the mounting plate is simply bolted to the brew boiler mounting plate via some rubber mounts to minimize any vibration and while running.  Securing the outside of the pump motor assembly  required me to make a couple of brackets that sit on the base plate of the coffee machine. I have made them significantly lower than the boiler side to make use of the space provided by the rounded back of the La Mondiale case, effectively allowing it to sit as low as possible.  The two benefits I see this being are that it allows the maximum room above for the yet to be installed steam boiler and secondly, it moves the pump away from the high temperature brew boiler. I have considered placing a heat shield between the pump motor and brew boiler also but I’m in two minds about whether this will be necessarily or not. Time will tell I guess. ~ richard muhl

And the project begins

Today I will be commencing a project I’ve been thinking of for some time.

The plan is to take a standard issue Italian domestic espresso machine and punk it by installing a dedicated brew boiler and every other refinement I can think of.

I absolutely love the Synesso Cyncra brew boiler and group actuator. It looks fantastic and has that instantly recognizable design (to those in the know) that will make this machine extremely unique.

The stainless steel boiler itself is quite compact which will help when it comes to fitting everything in the very limited amount of space available. I’m going to ditch the vibrating pump and install a small rotary pump and bypass regulator. The original heat exchanger boiler can stay on as a dedicated steam boiler.

With the obvious exception of the Cyncra Group, I want this machine to look like a standard Isomac from the front. I’m using a Isomac La Mondiale as it has the rounded form that gives me more space to play with. I also like the unique style of the steam and hot water valves etc, so I’ve taken a new La Mondiale off the shelf and raided the Synesso Parts bins in the workshop and I’m ready to start. ~ richard muhl