skyandtelescope.com • SEPTEMBER 2019 73
What makes it so massive? The size
of the parts, for one. The right ascen-
sion axis uses an 11.5-inch bronze
worm gear with 576 teeth, and the
declination axis incorporates a 9-inch
worm gear with 450 teeth. (He designed
and machined both in his own shop.)
The axle shafts, outer case, coun-
terweights, and mount base are all
machined from stainless steel. Brush-
less DC motors direct-drive the worm
shafts on each axis, with servo feedback
provided by an optical shaft encoder
having 40,000 pulses per revolution.
That alone is a machining marvel,
but Tom then proceeded to comput-
erize the whole thing, using a small
Raspberry Pi for a controller, industrial
pic-servo motion control boards from
Jeffrey Kerr LLC (jrkerr.com), and an
Ultimate GPS module. He wrote the
control software in Python and has
made it all available as open source on
GitHub.com. SkySafari running on a
smartphone connects to the robotic
tTom photographed the
2017 solar eclipse with his
homemade 10-inch New-
tonian on his homemade
equatorial mount.uThe mount is too heavy to
carry, so Tom built a forklift
to move it.controller over WiFi to provide touch-
screen control of all Go To functions.
A mount this hefty requires a hefty
tripod. Tom uses a Software Bisque
Paramount Pyramid Portable Pier. As
Tom says, “You can’t be too solid for
astrophotography.”
So how does this magnifi cent
concert of machining and electron-
ics perform? Like a dream. Tom took
it to Smith’s Ferry, Idaho, to view
the total solar eclipse of 2017, with
photographic results seen below at left.
Plus he has imaged many other deep-
sky objects, and the mount performs
beautifully.
It took 18 years from start to fi nish,
but the experience has been one of con-
stant reward. Of his long journey, Tom
says, “It’s interesting to note that when I
began in 1999, many of the technologies
that have made my project such a success
did not yet exist.”
And now, thanks to
Tom’s persistence and
adaptability, BlueShift
not only exists, but
excels and astounds.
When I jokingly notedthat this mount could probably make a
Volkswagen track if you could just bolt
it on, Tom’s response was, “The angular
contact bearings on the right ascension
axis are rated at over 16,000 pounds
static load each, so a Volkswagen would
be too easy!”
I’m gobsmacked.
Anybody have a spare
Hubble to put on this
thing?
Watch a video of
Tom assembling Blue-
Shift at https://is.gd/
blueshift.
Contact Tom at
[email protected].■ Contributing Editor
JERRY OLTION would
supply the Volkswagen
just to watch it happen.pThe Go To controller is built around a small
Raspberry Pi computer.BC D