2013-11-01

The manual for the Buon Caffé model 330 claims that the machine “provides outstanding steaming power”, but experience has shown it to be lacking. Fortunately, it can be made more powerful by exploiting a mechanical design flaw.

On the front of the machine is a dial with stops at Steam, Ready, and Brew:

At Ready, the heating element is regulated by a thermostat so as to maintain a steady internal steam pressure. At Steam, the heating element is unregulated and a valve is opened to allow steam to escape:

Position	Heating element	Wand valve
Ready	Regulated by thermostat	Closed
Steam	Unregulated	Open

Behind the dial, these simple “programs” are encoded in a plate cam. Rotating the dial causes the cam to press and release switches that control individual components such as the heating element or a solenoid valve.

There is a slight flaw in the transition from Ready to Steam, however. At this unlabeled position—

—the heating element is unregulated but the escape valve is not yet opened:

Position	Heating element	Wand valve
Ready	Regulated by thermostat	Closed
Unlabeled	Unregulated	Closed
Steam	Unregulated	Open

Once set to this position, a clock is ticking. Steam pressure builds up with no escape, and left unattended the machine would self-destruct. But this power can be wielded.

Taken to the brink of catastrophe, but released in time, the model 330 can provide outstanding steaming power indeed.