by timo888 on Wed Oct 31, 2007 7:24 am
Joking aside, there is such a difference in the way manual levers and spring levers do their thing to the coffee that I consider their visual similarities to be a superficial resemblance.
Brew pressure profile is one of the core attributes of any espresso machine. A very adept barista might be able to mimic with a manual lever the brew pressure profile of a spring lever ( H-B member jepy has done so with a computer-controlled pump machine IIRC) -- but except for that scenario, the two classes of domestic lever are radically different in how they bring pressure to bear upon the puck, and these differences produce significant differences in the cup.
Where the spring puts an absolute limit on the brew pressure (domestic spring most likely 6 to 7 bars) and the spring lever's pressure trails off towards the end of the pull owing to the dynamics of the decompressing metal, the manual lever's pressure can ramp up slowly or quickly, oscillate, wobble, dip and dive, or go high enough to bust a gasket.
Speaking of gaskets, home-maintenance is much more challenging with a domestic spring lever.
But I still like spring levers a lot. Don't get me wrong. The Lusso's temperature stability puts it in a duty-cycle (domestic) class all by itself ... at least until some other domestic spring lever with a thermosyphon struts down the pike.
Regards
Timo