The Grinder
A typical blade grinder produces a mind-shattering crackle when it first
turns on and can burn the beans. You also have to scrape out the oily
grounds that get stuck in the chamber. A burr grinder is better, but
good electric ones are expensive and a pain to clean. Luckily, Julie had
a grinder made for camping, and it heroically donated its ceramic burrs
to the cause.
To power it, I used a Pittman 12v gearmotor I'd been tripping over for
years. At 218.4:1, the speed was far too slow but since they come in
several speeds I figured the gearboxes were modular. Sure enough, a bit
of rearranging of the gears yielded a usable ratio.
The grinding chamber is three pieces of machined acrylic bonded
together. The top of the chamber locates the motor and has a complex
"funnel" opening to accept the beans. The bottom locates the grinder and
also tapers to guide the beans into the burr. Coupling and shaft are
stainless steel.
