Internals - Water heater

The first thing we need to decide when planning to build an espresso machine is what kind of water heating system to use. This has the largest impact on the rest of the system.

The water heater is probably the most defining aspect in the machine's internals and there are many different systems, but the most common three are as follows:

• Thermoblock:
• Thermoblocks work like an instant hot water system. The water is pumped through a series of channels in a heated metal block which brings the water to brewing temperature by the time it exits.
• Thermoblocks can also be used for creating steam by superheating them and pumping in little bursts of water which are flashed into steam. Many low range consumer machines attempt this to varying degrees of success.
• Thermoblocks are cheap and usually made out of aluminium (which corrodes more quickly than their brass or steel counterparts -- and you don't want aluminium in your coffee). Suffice to say thermoblocks are found in the cheapest machines and are considered very entry level.
• Boiler:
• A boiler is just that, a pressure-sealed enclosed space with a heating element into which water is pumped. Boilers typically have a water pipe leading out the bottom for brewing shots, and a steam pipe coming out the top for steaming milk.
• The larger the boiler the better really. It may take a little longer to heat the water initially, but it also means that there's more steam to use or less recovery time after each shot. 
• Boilers tend to accomplish the best quality steam because the pressure can be better regulated so it's more consistent throughout steaming, especially with larger boilers. No more splurting wetness into the milk.
• Heat-exchange boiler:
• This is arguably the best design. A heat-exchange boiler is a boiler (see above) which has an enclosed pipe that runs through the boiler and the hot water in it. So as the water goes through the pipe, it is heated to the temperature of the water surrounding it inside the boiler. 
• With a heat exchange-boiler machine one can usually steam milk and pull shots at the same time without having to wait for the boiler to adjust between brewing and steaming temperature (as with the conventional boiler).

Our machine will most likely use a dual boiler system, one for steam and one for water. But first, we have to figure out where we can procure such implements.

We could... perhaps, design it ourselves.

Basics - Extraction

Greetings, I'm the co-conspirator in this caffeinated quest.

Very simply, an espresso extraction works like this

• Water is drawn from a reservoir or water line and pressurised using a pump. 
• The water is heated to ~92 degrees Celsius in a boiler, a thermoblock, or a heat exchanger.
• The heated water is then forced at a pressure of at least 9 bar through the finely ground and tamped coffee until just before the shot begins to lose it's rich golden brown colour.

This should result in ~30 or ~60 ml espresso depending on the amount of grounds in the portafilter (single or double shot), and how they are tamped.

So that's some basic parameters we need to fit our machine into and some general targets to meet.

Plan of attack

A few things should be outlined in order to maintain steady progress and not get bogged down in details when conducting this project.

First things first, a rough idea of phases should be set down to list deliverables.

1. Scope definition - produce a small brief to keep a clear picture of exactly what we're trying to achieve with this project. Produce a tentative timeline to keep us on track.
2. Research - a big one, here. We need to produce as many detailed notes on how a machine works, how espresso should taste (so we know if our machine is any good!), what parts do well in what situations, what is suitable for our needs, how much should we budget for, how electronics will function, document other peoples own DIY efforts and lessons learnt, and the list goes on. This will be a major chunk of the first few months, so we are as prepared as possible going in to the following phases.
3. Design - a compendium of sketches, 3D models, inspiration sources and similar - culminating in a few shortlisted designs. The best one shall go on to be built.
4. Material procurement - produce a BoM (Bill of Materials) so we can source them from the cheapest suppliers. Get in touch will suppliers and/or experts for recommendations on components. Produce a budget to prevent unneeded spending.
5. Fabrication - decide what will be put together ourselves, and what will have to outsourced. Assemble the machine.
6. Commissioning - test the machine for flaws in construction, test espresso quality, assess functioning of all components, tweak and/or repair necessary components.

Then we shall enjoy the fruits of our labour with as much espresso as our hearts desire!

Capturing the look, pt. I

Clockwise from top left: Linje Espresso Maker; Antique William IV mahogany partners writing table black hide surface with gilting;  manager's desk at Fray Bentos meat packing factory in Uruguay; Antique William IV desk circa 1835; wooden picture frame; dark wood paneling in elevator; Steampunk Workshop von Slatt Original keyboard; Brunopasso espresso machine designed by Tadahito Ishibashi

Compiling a repository of images for design ideas, and a cursory Google search has yielded the above results. We're thinking of going with an old-school, dark wooden design - antique desks seem to provide ample inspiration and beautiful aesthetics that we might use for our coffee machine.

The Brunopasso and Linje machines show a departure from traditional design, which I might draw upon to break the mold when it comes to our machine. Then again, the old-school look will is probably inclined towards geometric shapes, so a radical design may go against this vision. Only time will tell.

The beginning of something wonderful

All it takes is one simple statement, and a whole smorgasbord of ideas start flowing in...

Recently I was out to lunch with a friend of mine and I mentioned, kind of flippantly "Let's build our own coffee machine from scratch"; both of us are coffee enthusiasts and enjoy the many wonders of the coffee culture in Melbourne. In the intervening days, I have become in love with this idea of building our own - to understand the ins and outs of the machines which consistently serve us our favorite hot beverage.

I have created this blog to document the process of planning and construction of our own coffee machine; to convey the challenges and triumphs we encounter on this hobby project. We are by no means experts, and will no doubt encounter many problems. For anyone also somewhat interested in their own DIY espresso machine, hopefully this blog may inspire you and highlight problems to avoid, or provide neat things which work. In that sense, I would almost consider this "open source espresso" - eventually becoming a place where people can get plans and ideas for their own projects.

More to come soon.