How an espresso machine works, taken apart

July 3, 2026 #espresso#coffee#interactive#explainer

I have spent a lot of time staring at my espresso machine wondering what actually happens in the few seconds between pressing the lever and watching a shot fall. So I took one apart, on the page, and wrote the explainer I wanted to read: How an espresso machine works.

It follows the water the whole way through - out of the tank, through the pump, into the boiler and heat exchanger, and finally through an E61 group head - and ends at a finished shot with crema. The machine I chose is a classic E61 heat-exchanger design, because the heat exchanger is the clever, slightly counterintuitive bit that makes it worth drawing.

The prose is deliberately lean. The explaining is done by roughly 19 interactive figures you can drag and scrub, so you can see the pressure build and the water move rather than take my word for it. Read it here: espresso.hirschmann.io.

It has a sibling article on the other half of the story, the bean itself: how coffee roasting works.

The format is borrowed from Bartosz Ciechanowski - a long scroll with draggable figures and words that point at the renders. I built the visualizations with Fable (Claude, by Anthropic), which did the patient work of turning physics into things you can poke at. This is the espresso detour I promised in my first post here; the coffee obsession finally leaking onto the site.