The E66 by Faema was the first machine to have adjustable volumetric controls.
The first use of electronic flow-meters in an espresso machine was described in a 1978 patent lodged by Rancillio. Their 1978 patent describes a مقياس التدفق very similar to the kind used on modern machines, with a pair of magnets mounted on an impeller that spins as the water flows past it.
The advent of electronic controllers in espresso machines from the 1980s onwards paved the way for much more precise and complex control of espresso machines.
In the 1990s, Seattle café owner David Schomer was extremely vocal in calling out traditional manufacturers for their failure to achieve temperature stability. He published his theories in a column in Café Olé magazine in the ’90s and in his 1996 book Espresso Coffee: Professional Techniques.
Schomer’s book convinced many users of the influential alt-coffee forum of the importance of temperature stability. In February 2001, Schecter posted on the alt-coffee forum about his successful attempt to install a PID controller on his Rancilio Silvia prosumer espresso machine.
Because a PID varies the amount of power used, the heating elements do not have to run at their maximum energy output for long periods.
In 2001, the Dalla Corte company of Milan, Italy, built the Evolution, which featured an independent PID-controlled brew boiler in the top of each group head.
In 2004, Scace produced the Scace Thermofilter for measuring the temperature at the group head, which gave rise to a widespread awareness of the successes and failures of different machines.
In 2012, the Simonelli Aurelia II, by Nuova Simonelli, achieved a temperature stability of ∓0.1°C.
In 2017, La Marzocco redesigned the classic lever mechanism to make it safer and more temperature stable, with a PID-controlled heating element embedded into the bayonet ring of each group.
To achieve temperature stability at the group head, Decent Espresso combines 110°C (230°F) water with room temperature water just before the water mixture enters the group.