It All Starts With The Mount
At some time or another, most amateur astronomers acquire through some
means or another a telescope that doesn't have a tripod. Or, in some cases,
a telescope with an inadequate tripod.
If you've done much shopping for telescopes and accessories, you know by
now that a decent tripod costs a couple hundred dollars or more. That's kind
of a costly experiment, to buy a tripod for that money in the hope that it will
work.
This page describes a tripod that I built for a couple of my telescopes.
The total cost was only about $50 a few years ago. I get double duty with
this design, and if I happen to lay hands on another small scope to play with,
it'll be easy to add an attachment to carry that telescope as well.
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The Basic Tripod
Shown at left is the basic pipe fitting tripod design. It consists of a section of
2" pipe for the basic stand.
A 2" flange is mounted to a double-layer 3/4" plywood base.
Three 1" lengths of copper pipe extend from the center pipe to the
extremes of the triangular base. Copper was used because the ends could
be flattened for easy fastening to the center pipe and base.
An even more solid mount could be made by welding pipe legs onto the
center pipe, and letting them extend to the ground. This would eliminate
the plywood base.
I choose this design at the time because I didn't have a welder in my
tool arsenal.
On top of the tripod is mounted a head designed to support a 2" refractor.
It would easily support a 60mm refractor, and likely a 70mm to 80mm refractor.
By going to 2 1/2" or 3" pipe instead of 2", it could be
sized up to handle a larger telescope.
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The Tripod Feet
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The tripod feet are shown in this image.
First I mounted three 3/4" flanges to the underside of the plywood
base.
Then I simply screwed in three short (each the same length) nipples into
the flanges, and capped them to prevent them from digging into the ground.
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The result is a stand that is portable enough to be easily moved around
the yard, yet very sturdy.
In addition, about the only tools I needed was a pipe wrench or large
pliers, and a drill.
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The Tripod's Refractor Head
Shown is the head that can be mounted on the tripod to support the
2" refractor telescope.
It consists of a coupling that connects to the base, an extender to
accommodate the length of the telescope, and the bearing sections.
The azimuth bearing is formed by a 90 degree street elbow.
The street elbow screws into a flange that is mounted to a wooden bracket
that holds the telescope. This makes the elevation bearing.
To make the thread bearings work smoothly, I polished the threads with some
valve grinding compound obtained at a local auto parts store. The valve
grinding compound is a kind of gritty, greasy paste.
I put some of the compound on the azimuth threads, then screwed on the
street elbow. I tightened to hand tight the street elbow and backed it off
repeatedly. The grinding compound polished the threads of both the extender
pipe and the street elbow. After a few minutes, I was able to turn the fitting
a couple of turns further before the street elbow would be tight. Once
you've gained a couple of additional turns, the threads are probably
polished enough.
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I then removed the street elbow and cleaned the extender and street elbow
threads, applied a light coating of grease, and screwed the street elbow
back on. It now turns smooth as butter.
I did the same to the elevation bearing formed by the horizontal
section of the street elbow and the flange.
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The Tripod Supporting Refractor
This image shows the tripod with the refractor head in place, supporting
the 2" refractor telescope.
It is, admittedly, an altazimuth mount, but one that is sturdy and has
smooth bearings.
While not light as a feather, the unit is light enough that I can leave
the tripod and telescope assembled together, and still carry it out to set up,
or move around the yard.
That provides some pretty short setup time, and lets me squeeze in some
fun observing even if I only have 45 minutes or so for the entire session.
The telescope moves easily and smoothly to each target, and remains in place
from the slight stiffness in the large bearings. Pointing adjustments on target
are made with light taps to the telescope tube. Vibrations from the alignment
tapping stop immediately due to the mass of the tripod.
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Tripod With Resuscitated 60mm Monolux
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One nice thing about this simple but ample tripod is its flexibility.
Since mounting refractors involves nothing more than a hose clamp or two,
it's easy to switch from one telescope to another.
As an example, here's the same refractor tripod head with a resuscitated
60mm Monolux telescope in place. The Monolux is an old Japanese designed
telescope with a classic air-spaced objective. With a bit of loving care and
the addition of a hybrid star-diagonal, this telescope still makes a fine
performer, and is supported very well by the pipe-fitting tripod.
Below the telescope, you can see the eyepiece table that's recently
been added to the tripod. It's simply a 1/4 inch thick piece of plywood
with several 1 1/4 inch diameter holes drilled into it, and fastened to
a wooden mounting ring that clamps to the tripod post.
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Adding Setting Circles
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One thing you might consider as a refinement to your pipe fitting tripod
is to add setting circles. While setting circles are more commonly a thing
found on equatorial mounts, you can definitely use setting circles to find
celestial objects with an altazimuth mount.
The setting circles in this case were created with a perl script. The perl
script can generate setting circles of any given diameter, and marks them with
1 degree, 5 degree, and 10 degree tick marks. The perl script creates a
postscript file ready for printout. You can download a Setting Circle PDF file if you wish and print
out accurate circles for yourself. If the circle isn't the right size, perhaps
you can use a Xerox copier to copy it to a more appropriate size.
I made my circles to be 6.5 inches in diameter. The printouts of the setting
circles were mounted on 1/4 inch thick tempered hardboard and coated with Mod
Podge to protect them. The elevation settings need only be a quadrant going
from 0 to 90 degrees. The quadrant can be cut from a full circle.
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I cut the elevation quadrant and mounted it onto the bracket that holds my
telescope, as shown. To properly position the elevation pointer, I first
leveled the tripod using a level on the base. Then I set a level on the
telescope and rotated the elevation bearing until the telescope was pointing
level. Next, I mounted a pointer (a large nail) so that it pointed at the
quadrant zero reading while the telescope was pointing level.
I mounted the azimuth circle by mounting it onto a split ring cut from
plywood. The split ring was cut a tad too small to fit over the shaft of the
tripod, but with a cut through the ring (the split), it can be sprung open
enough to fit snuggly around the vertical shaft of the tripod. In this way, I
can turn the azimuth circle to proper position when aligning the telescope. I
added a pointer for reading angular position.
How Do You Use Them?
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The easiest way to make use of your setting circles is by using a
planetarium program on a laptop. Xephem, Stellarium, or Kstars on a laptop lets
you see a star map of what you might want to look at. You click on an item, and
the azimuth and elevation show up on the screen. For Kstars, a right click will
do it, then select details from the pulldown, then position.
For Stellarium and Xephem it's a left click.
To make easy use of azimuth and elevation values:
AT the Beginning of your observing session:
Level your tripod.
Point the telescope at Polaris
Rotate the azimuth circle to read zero azimuth
For the remainder of the observing session:
Select an item in your computer almanac, click to bring up azimuth and
elevation, then point your telescope to those coordinates.
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Generally, if you've leveled your tripod and zeroed your azimuth on
Polaris, an object will either show up in your telescope FOV with a low
power eyepiece, or be just outside of the FOV and easily found with a bit
of careful searching.
I have a program in an HP128 calculator that holds a couple of star
catalogs (the Messier and Caldwell lists). It does the same translations as
the computer planetarium programs, and gives me more portability. Pointing
by setting circle saves me loads of time, especially on the dimmer objects
that don't show in my finder.
I can also use my Old Laptop with Linux to make use of my setting circles. While the laptop
is old and has minimal resources (only 83MB of memory), it runs Debian
Etch with Xephem just fine. So you don't need to go out and buy an expensive
laptop for this duty. Get something cheap from Ebay and put Linux
and Xephem on it. If you get one as old as mine, likely Kstars and
Stellarium will be too big for it, but Xephem requires much less resource.
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Amazingly, a pipe fitting tripod with setting circles and an old laptop (or
calculator program) can automate your telescope to be nearly as handy as a
computerized telescope. Is that neat or what?
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The Cassegrain Wedge
This image shows a simple wedge I made to support my Meade ETX 90. I have
the older model that has a motor only on the right ascension axis, so to
get use from the clock drive the telescope must be in an equatorial
configuration.
The wedge is a simple triangle of wood cut to tip the telescope's polar
axis by my latitude angle. A bit more thought and I could have built an
adjustable wedge.
To the bottom of the wedge is mounted another 2" flange. The flange screws
to the telescope base, giving a solid yet portable mount for the Meade ETX 90.
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The Tripod Supporting Cassegrain
This is an image of the Cassegrain wedge mounted on the tripod base,
supporting the Meade ETX 90.
As you can see, the extender section of pipe isn't needed for the
Cassegrain telescope, so it has been removed.
I've found this to be a very solid mount for the ETX, and it would likely
support at least the ETX 105 as well.
Again, by scaling up the size of the pipe, a larger telescope could
be handled.
This is the mount that was used for the Meade ETX 90 when it was used
to make the moon images and planet images shown on the etx page.
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Personal Notes
If this cheap tripod design gives you some slack, money-wise, you might want
to take another look at some small Cassegrains, knowing that with simple tools
and tens of dollars you can make a fine tripod.
You could also take the risk on perhaps a 60mm to 70mm refractor. The 60mm
makes a great first telescope, but often is shipped with a flimsy mount. This
mount would cheaply transform an optically decent 60mm into a fine performer. I
use it often with a 60mm f/16.7 refractor and a 60mm f/11.7 refractor.
With a resuscitated old 60mm Monolux, my pipe tripod, and my setting circles
I have hundreds of targets within my reach then can be located quickly, and
hundreds of dollars or more of savings in my pocket.
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