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September 2009 Newsletter

Dead espresso machines turn up in my office every now and then,
usually donated by customers. When time permits I pull them to
bits to try and work out why they've failed.

A recent slow day gave me the opportunity to demolish a 6 year
old Baby Gaggia (too easy, a large portion of the inside of the
boiler had dissolved and blocked the narrow tube to the solenoid
valve), a Chinese made superauto and a Sunbeam EM6900.

The Gaggia went back to its owner with a note suggesting she get
a replacement boiler. The superauto had a burn mark and blown
fuses on its circuit board, presumably a dud component. The
EM6900 had two problems; first, the steam had stopped working,
then it became impossible to brew a shot without leaking around
the group.

After ratting the Sunbeam, it appeared that the steam solid state
relay had gone, and some of the screws which attached the
thermoblock/group to the group collar had stripped.

It was at this point that I sat down and thought hard about the
whole design philosophy behind the Sunbeam 6900 series and the
Chinese superauto. These were incredibly complex machines,
precision engineered up to a point, which unfortunately seemed to
be a price point. The plumbing was a good example: the Sunbeam
"brew" thermoblock is connected by an exquisitely intricate set
of copper and brass compression fittings, a miniature version of
commercial machine piping.

On the other hand the steam thermoblock is connected by crimped,
fabric covered silicone hoses, the worst possible engineering
solution for the highest temperature, highest pressure area. The
group/group collar mating is frankly cheap and nasty, and in my
opinion unnecessarily so. 5 fallible screws could have been
replaced by 4 bolts and matching nuts, a no-fail solution.

The thing that really annoyed me about the group collar casting
once I got it off was that it would have been trivially easy to
have shaped it to fit industry standard 58mm portafilters instead
of just the Sunbeam one, potentially reducing production costs
and increasing market appeal. A major lost opportunity.

The superauto had 6 (!) microswitches, a failure in any one
shutting down the whole machine, and microswitches fail all the
time.  One thing that both the Sunbeam and the superauto had in
common was that disassembly to reach the failure points was a
drawn-out, complex process. It took me almost an hour (and
machine techs charge $100.00/hr) to get to the point where I
could undo the remaining three screws holding the group collar in
place.

"NOT designed to be repaired" is the only way I can describe
these machines. Unlike Gaggias, Lelits and Silvias there is a
presumption that things won't fail, coupled with bipolar design
decisions that ensure they will, and complex and expensive
disassembly routines.

The Sunbeam "Brain Box", a work of art including transformer and Solid State relays. One of the SSR's had scorch marks on the solder at the back. Complex, precision made, expensive? Cheap group collar casting and attachment points. This is the most stressed part of the machine, all the pressure ends up concentrated here.

Finally, this month's special coffee is the second most popular
(after Yemen Mokha) special we have ever offered. The second of
my "boat" specials, it is:

Costa Rica Tarrazu Miel
$45.00/kg

Smells like coffee, tastes like coffee, it's the coffee-est
coffee we've ever offered. Makes a killer single origin espresso,
too. No quantity restrictions since I placed my bid for this lot
in Dec. 2008 and got all I bid for. If you want to know what
coffee should taste like, try this.

Alan