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What happens in your countertop factory (aka superautomatic espresso machine)

May 2013

What a barista does by hand, a superautomatic espresso machine does automatically, at the touch of a button. Like a factory on your countertop, the machine controls each step in the process.

Step Process Image
1 - Grind beans Motor engages one burr to rotate while the secondary burr remains stationary.
2 - Dose ground coffee A micro-switch communicates to the board once it has been triggered and the pre-set dosage amount has been reached (some machines do not allow dosage to be changed). This activates a solenoid that opens a gate valve and the ground coffee is dropped into the brew group.
3 - Tamp into a “puck” The brew group's motor engages with the brew group's gears and it moves the dosing chamber laterally and then upward to press against the stationary tamping surface.
4 - Pre-infusion Board triggers the pump to engage for a small number of rotations of the water turbine in the flow meter and then opens the water path via a solenoid, delivering a small amount of water down onto the coffee puck.
5 - Extract espresso Board triggers the pump to engage for a longer duration that can be set by the user. Depending on how the volume is set, it correlates to a specific number of rotations of the water turbine in the flow meter in order to produce a shot of espresso of the user's desired volume. This range is generally around 1/2 oz to 8 oz.
6 - Clean-up After the extraction is complete, the brew group's motor engages the gears to lower the dosing chamber. This will also push up the bottom of the cylinder, so that the coffee puck rises up and, when the chamber moves to “home” position, the puck slides into the dregs box via a little chute.

Photographs courtesy of Seattle Coffee Gear.

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