COFFEE
The variable I chose to attack was the problem
of tamping. I’d heard about automated tamping
systems, which remove the guesswork of manually
pressing grounds into the portafilter with a hand-held tamper, and instead consistently provide
30 pounds of uniform pressure. This is great, but
automatic tamping machines cost hundreds of
dollars. One clever member of the home-barista.com
forums scoffed at the price tag and built his own,
using a manual lever juicer as the platform.
I decided to give it a try.
I considered a few requirements for my auto
tamper: a way to know when I’ve hit the magic
30lbs, a way to secure a commercial tamper base
to the down-shaft of the juicer, and a method of resting different portafilters with their oddly shaped
undersides on a load-bearing surface.
Through some informal research, I determined
that the most common method of indicating correct
pressure in a commercial auto tamper is with a
“clicker” system. This is a calibrated spring and ball
bearing mounted at a right angle to the shaft. One
great feature of these systems is that they stop all
downward pressure after the threshold has been met.
Home baristas have more commonly opted for a
heavy spring mounted over the juicer shaft, kind of
like a car’s coil-over suspension. Enlisting the aid of
a bathroom scale, they test for the 30lb depth and
then mark a calibration line on the shaft. This is an
elegant, simple design, and they’ve reported excellent
results. Another simple method, suggested by a
gearhead friend of mine, would be to replace the lever
handle on the juicer with a torque wrench adjusted
to pop when 30lbs are measured at the tamper.
While the torque wrench would have functioned
well, I was also concerned with aesthetics. I wanted
to maintain the quasi-steampunk look of my
espresso machine, with its beautiful pressure
gauges front-and-center. I wondered how I could
use an analog dial to read out my tamping force.
After another brainstorming session with my friend,
we had it: a pressure gauge connected to a hydraulic piston coupled between the juicer’s down-shaft
and the tamper base.
To set these plans into motion, I began sourcing
parts. The foundation for the project is the juicer. It
can be had for about $20 at T. J. Maxx or Marshalls,
and I also found many on eBay — just search for
“manual juicer.”
The piston, gauge, and fittings proved a bit harder
126 Make: Volume 12
MATERIALS
Manual lever juicer around $20 from department
store clearance sales or ebay.com
Total cost should be $60–$100, depending on
where you find your parts.
TOOLS
Needlenose pliers to remove lever handle
retention clip
to track down. I found many sources online, but
they were all too expensive. I finally hit the jackpot
at Norton Sales ( nortonsalesinc.com), an aerospace
scrap yard in North Hollywood, Calif. There, I picked
up a stainless steel actuator piston for $5, a 100psi
gauge for $7, and the pipe and fittings for a few bucks.
I went to Industrial Metal Supply ( imsmetals.com)
for scrap aluminum stock. A neat little store in
