Grind
Click the side panel to take it off or put it backCold water: tank, pump, over-pressure valveHot water: boiler to the group headGauge needle: pressure above the coffeeClick the side panel to see inside, or take the whole machine apart: the hopper, top, head, portafilter, water tank and back lift straight up, and so do the working parts: the boiler with its fittings and wiring, the over-pressure valve with its hoses, and the pump. The frame, control box and drip tray stay on the bench. Pulling a shot is played three times faster than life. The pump pushes cold water from the tank through a braided hose into a tube that runs through the copper boiler; the boiler, kept hot by its element and switched by the pressure switch on top, brings that water to 93 °C on the way through. For the first 7 seconds it runs gently to wet the coffee, then at full power. The pump does not set the pressure by itself: the packed coffee in the portafilter resists the flow, and that resistance is what the gauge shows. Past 9 bar the over-pressure valve opens and sends the extra water back to the tank through the thin line. Change the grind and pull again: coarse coffee lets water rush through at low pressure in a few seconds (sour), fine coffee chokes the flow and the shot drags on (bitter). The middle setting gives 36 g in about 28 seconds from 18 g of coffee.