Sky & Telescope - May 2020 - 72

ASTRONOMER'S WORKBENCH by Jerry Oltion

Drew Sorenson can
haul and set up his
portable pier mount
as easily as he can a
truss Dobsonian.

Pipe-Fitting
Mounts
An old idea is still going strong.

is a refractor nut. He's also an amateur
telescope maker. So, not surprisingly,
he's made several refractors, his largest being a 6-inch f/10 with lenses he
ground himself.
But I'm not here to tell you about
his telescopes. I'm writing about his
mount!
Drew contacted me after he read my
article on "Hobby Killers" (S&T: Dec.
2019, p. 36). He said, "I am very frustrated to hear so often that people don't
consider larger refractors because they
would need a mount that would cost
over $1,000. I think the hobby is at least
'stunted' (maimed?) when people don't
think they can enjoy what refractors
can contribute visually because of lack
of an expensive mount." He proceeded
to show me a mount that costs about
$75 in parts and works like a charm
even for a large refractor.
To fully appreciate this mount you
need a little history. Back in the early
days of amateur telescope making,
nearly every scope was placed on a German equatorial mount. Commercial
mounts of any sort were rare, however,
and expensive, so most ATMs built
their own mounts as well as their own
scopes. They used the easiest, simplest
materials that would do, which more
often than not meant pipe fittings.
Pipe fittings work great for equatorial mounts, especially for people living
around latitude 45°N. You can use a
simple 45° elbow to angle the polar axis,
and a tee off that for your right ascension and declination motion. The screw
threads act as your bearings: With a
u The permanent mount is solid as a rock . . .
because it pretty much is a rock, with a pipe in
the top.

72

M AY 2 0 2 0 * S K Y & T E L E S C O P E

little grease and tightened until they're
just snug, they provide plenty of motion
- and smooth motion at that - to aim
a telescope anywhere in the sky.
With the advent of the Dobsonian
mount, however, since most ATMs were
making reflectors, they abandoned
pipe-fitting mounts in favor of plywood
altitude-azimuth (alt-az) mounts, with
the result that you don't see many pipefitting mounts today.
Drew is an exception to that rule.
He has been using the same pipe-fitting
mounts for more than 30 years, and

they still work beautifully after all this
time. Where Drew parts way with tradition, however, is in the "equatorial"
part. He went alt-az from the beginning, preferring the intuitive up-down,
left-right motion and the simple construction of an alt-az mount.
And because he likes looking
straight through his telescopes (no
mirrors!), that means getting them
high off the ground, so he built his
mounts into piers. He has two that he
uses all the time: a permanent concrete
installation and a portable PVC-andplywood one.
The permanent one is a two-step
pier, with a vertical pipe embedded in
the top. A simple 90° elbow atop the
pipe provides the azimuth motion, and
a nipple in the other end of the elbow
provides the altitude motion. Drew
welded the nipple to a chunk of wide
channel iron, but a person without
a welder could bolt a pipe flange to it
just as well. The telescope is held to
the channel iron with a simple rubbercoated cable.
The portable pier uses 2″ × 8″ legs
and an 8-inch-diameter PVC tube.
Notches in the tube keep it from twisting, and guy-wires keep it stable. The
upright iron pipe at the top screws into

DRE W WITH SCOPE: A .J. SORENSON;
MOUNT: DRE W SORENSON

IOWA AMATEUR DREW SORENSON



Sky & Telescope - May 2020

Table of Contents for the Digital Edition of Sky & Telescope - May 2020

Contents
Sky & Telescope - May 2020 - Cover1
Sky & Telescope - May 2020 - Cover2
Sky & Telescope - May 2020 - 1
Sky & Telescope - May 2020 - Contents
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