Building a Coffee Machine

Hi and welcome. I took one apart a few years back (for the recoverable parts) and it was very educational too.

My first question then is what sort of machine are you thinking?

Some are pressure fed (and by nature need a specially designed boiler) and others are pump fed with an "instant" hot water feeder.

There are other variations (percolator for instance) but they are quite complex because you're dealing with (at least) mains voltages for the heaters which is inherently dangerous. The specially designed pressure boilers are made to boil water to at least 100C (in a pressure system it's possible to get the water even hotter).

These boilers are supplied with electromechanical temperature operated switches which will allow the boiler to run dry without destroying the element.

Can it be done? Sure.

Should it be done? Absolutely not by hobbyists.

The "safest" version of these is the one that uses steam pressure to push water through the "plumbing" and drip feed boiling water into a filter. The more complex ones, based on the classic Italian design, pressurise the coffee and force boiling water through. So even the plumbing has to be done with special tools to make sure nothing leaks.

So we have to consider the danger of electrocution with the less obvious potential for serious burns (from a leaking pipe - superheated steam isn't visible) or even an explosion from the boiler.

This probably answers your question as to why there's a dearth of information online. The patents for the various systems are public documents but the point with a patent is that you need the knowledge to build something from a plan. And they are weird, when I last applied for a patent I didn't even recognise the description of the thing I invented! LOL.

I'm sorry to be "that guy" but I'm ancient and rather safety conscious, particularly in the millennial climate where safety has developed to the point where we're rarely in danger. When I was a kid we had lead in paint (which probably explains why I'm a bit dim) and televisions that could kill you if you were daft enough (waves hand) sticks a screwdriver through the vents at the back. And a lot more, we got hurt - a lot - and those of us who survived learned a lot about danger. And I'm also the sort of idiot that almost suffocated in sulphur dioxide and exploded nitrogen triiodide in my face - I wasn't so much red faced, more a shade of purple. I got a couple of very high voltage belts by not using proper earthing (and all of that before I left school).

I did a lot of stupid things as a kid - and then I got married which was an even bigger mistake. 😉

Even pre-Internet we could get a lot of weird stuff (including radioactive materials) without anyone raising an eyebrow. I have the scars (internal and external) to prove it.

So I hope you'll understand why I'm a Negative Nellie when it comes to this stuff. No one wants to read about you being found dead from following instructions or advice you received here. Or even caused harm, serious injury or death to someone else. You'll note that when Matthew does any soldering he uses a fume extractor - these details matter. Your health and safety matters to me as much as it does you.

We're a great community here - suggestions for projects are always welcome.

Given simple drip coffee machines can be bought for around 30 bucks, I'm assuming you mean machines that operate with pressure.

I second the lovely words of caution by marcdraco. Building an espresso machine from scratch prerequisites a deep understanding how old and new machines work, and machining the parts to a high level of accuracy, which is required to deal with the pressures, around 9 bars usually.

You're playing around with superheated water in a pressurized system here. If you don't know exactly what you're doing, if you don't electrocute yourself, you might build a bomb by accident.

But that doesn't mean there is no potential for coffee-related projects. There are lever-operated machines that have a chamber you fill with coffee, tamp, add boiling water from a kettle, and then manually push a piston into the brewing chamber to create the pressure.

A modern machine that uses this principle is the Cafelat Robot . It's around 400 €/$ but has most of the capabilities that very expensive machines have, like pressure profiling.

Your project could be to figure out your own direct lever design and build a (prototype) machine that doesn't involve heating or electricity. Be mindful that if the water isn't heated, this will limit the achievable brewing temperature to around 90°C.

Another manual machine worth looking at is the Flair 58

If you want to take an existing machine instead, and turn it into something much more capable by adding sensors and a microcontroller, check out the Gagguino Project . You essentially buy a used Gaggia Classic (Evo) off ebay, buy an Arduino/ESP32 and other components, and mod it. Requires access to a 3D printer, will cost around 500 bucks and a week of your time.

The project tries to emulate the Decent espresso machine.

I'm assuming you already have a coffee grinder that can go fine enough for espresso, otherwise that's definitely required.

Excited to hear what you have in mind!

Welcome Limbis. Looks an interesting project that you tagged there. I saw the cost and went... not this decade! The reason for my abundance of caution is mentioned in more detailed in the USB-C mic official topic in a post from, I think, yesterday.

And I salute the utmost caution that the folks at the Gagguino Project are taking but I also note that where there's a buck to be made... they've been a victim of the abuse Open Source (hard and software) is often exposed to: bad actors and these are Steven Segal level of bad. It's something I'm troubled by in doing a (de-facto) upgrade of the mic and putting Matt's logo on there. It's his project, his design (my electronics but that's a passion and something I needed to keep my brain ticking).

It's in two parts - the main bit will be, I think, the the smallest P48/P24V capable, professional quality head in the world... I think... But there are a few short cuts you can take even with the low-cost parts I'm using and quality will suffer as a result. I'd hate to think some wise guy did that and sold them under Matt's banner? I honestly shudder and this thing, unlike the coffee machine, can't really hurt anyone.

Lack of input from the OP also suggests that he's looking for someone to tell him what he wants to hear vs. the abundance of caution anyone who has worked with pressure vessels will say. Oh that's another day something was looking out for me... In my teens I was a keen gardener who didn't know about UV's effect on plastics. So I pumped a 2 gallon pressure canister to the point where, despite being well under it's limit, exploded right in my face

And that's not even 0.5 bar!

I got wet and felt stupid but I could have lost an eye. I hope the OP does read these comments and realise we don't say this just to be bloody minded.