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skyandtelescope.com • JUNE 2019 75
Most of the upper end is 3D-printed.
Robert used a carbon-fi ber-infused
nylon material that’s lightweight,
durable, and stiff. The interior space of
most pieces is honeycombed rather than
solid, so they’re considerably lighter
than wood, and they have almost zero
fl ex. The biggest challenge with binocu-
lar scopes — keeping the images merged
as you move the scope around the sky —
is a non-issue in Robert’s scope.
The bottom end is
more conventional, with
aluminum trusses and
plywood mirror box
and rocker box. Why
didn’t he 3D-print all
that, too? “Because all
that stuff is best real-
ized in other materials
using other processes,”
he explains. “Plus 3D
printing is relatively
expensive over large
volumes.” However, the
parts of the scope that
aren’t 3D-printed were
CNC-routed or laser-
cut, so all the design
could still be done in
one piece of software.
Robert bought his
mirrors but designed
his own cells to support
them. And rather than fi ne-tune the
image merging by tilting the primaries,
as most binocular scopes do, he chose
to do his image merging at the tertia-
ries, where the adjustment knobs are
easy to reach.
Given the stiffness of the carbon-
fi ber-infused nylon building material
and the telescope’s overall rigid design,
there’s very little adjusting necessary.
A tweak after setup and the view is
often good all night. The scope can
move from horizon to zenith without
the images separating, and switching
eyepieces doesn’t affect merging until
Robert gets to his highest magnifi ca-
tion. Even then, it’s a simple matter to
re-merge.
One of the biggest bugaboos of
binocular scopes is their complexity in
setting up. Setting up Robert’s scopetakes about a minute: Place the scope
and base on the ground, slide the top
end upward and lock it into place, pop
a couple of eyepieces in, fi ne-tune the
merging, and you’re ready to go.
The eyepiece holders are another
great innovation that neatly solves a
common frustration with binocular
scopes. Set screws and compression
rings tilt the eyepieces, especially when
the eyepieces have safety undercuts. In
a binoscope, that plays
hob with image merg-
ing. Robert solved that
by printing individual
collars for each eyepiece.
The collars incorporate
neodymium magnets
that click them neatly
into place — exactly the
same place every time,
completely eliminating
set-screw tilt.
Robert also designed
fi lter cartridges so he
can pop various fi lters
in and out of the light
path without remov-
ing eyepieces. Those,
too, are held in place
magnetically.
That’s the beauty of
designing the scope dig-
itally and 3D-printing
it: the ability to refi ne the user experi-
ence. Robert says, “With my binoscope,
I wanted people to be able to just walk
up to it and use it intuitively.” He has
largely succeeded. I’ve watched people
use it at star parties, and they fi gure it
out within seconds. To adjust the eye-piece separation for their own eyes, they
just grab the eyepieces and push them
together or pull them apart. The focus
knobs are right where you expect them
to be. You grab the top end of the scope
to move it around the sky.
Robert calls his scope the “Drifter”
because it’s supremely suited to simply
scanning the sky in search of beauti-
ful sights. In a wide-fi eld binocular
scope, every view is a stunning view,
but there’s a sense of special delight in
sweeping across, say, the Double Cluster
or the Dumbbell Nebula without spe-
cifi cally looking for them.
That sense of delight is what it’s all
about. As Robert says, “I didn’t build
a telescope because I wanted to try 3D
printing. I started 3D printing because I
wanted to build a binoscope that never
existed before.”
We’re on the threshold of a new
design revolution. I’m convinced that
Robert’s experience, both the build-
ing method and the end result, will get
more people into amateur astronomy.
And there are still a million unique
scopes waiting to be imagined and built.
For more information, contact Robert
Asumendi at [email protected].■ Contributing Editor JERRY OLTION is
a big fan of binocular scopes, 3D-printed
or otherwise.pThe top end of the Drifter is mostly 3D-
printed. One side is uncovered to show interior
hollows and secondary spider design.pRobert’s computer is his workshop.pThe focuser design can be dis-
played as a wire-frame drawing or
as a solid object.