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A Tripod for Tabletop Dobs: this sturdy platform for small telescopes is easy to make.

Tabletop Dobsonian telescopes are becoming increasingly popular. Instruments such as Edmund Scientifics' venerable Astroscan, Orion Telescopes & Binoculars's StarBlast, and the new Astronomers Without Borders's OneSky instrument (reviewed on page 60 of this issue) are excellent examples of this genre. Although they are wonderfully portable, they can also be a pain in the neck to use unless placed on a sturdy table. Unfortunately, not everyone has a suitable platform at their favorite observing spot. That's where Peotone, Illinois, amateur astronomer David Fuller's Super-Simple Tripod #2 (SST2) comes in.

"I wasn't using my collection of tabletop scopes very often," Dave says. "I don't like kneeling on the ground, and the picnic table in my yard is located under 80-foot-tall trees." He tried mounting his scopes on heavy-duty camera tripods, but found them too wobbly. That's when he decided to make his own.

Dave's purpose-built tripod has the twin virtues of being easy to make and highly functional. You can put one together in an evening or two, and customize it to have your scope's eyepiece at an ideal height. The SST2 consists of only a few parts--three legs made of 2x4 lumber, a round "table" made of 3/4-inch plywood, and a spreader/eyepiece rack also made of 3/4-inch plywood. Add three hinges, a length of threaded rod, some nuts, bolts, and screws, and your bill of materials is complete.

The most critical step in making the tripod is cutting the top edges of the 2x4s to an angle of 221/2[degrees]. This ensures that when the tripod legs are spread apart, they butt up evenly against the underside of the platform. As Dave advises, "Getting these cuts right is important--take the time to ensure the leg's top ends are flat and equal." A table saw is ideal for making these cuts, but even a handsaw will work if you bundle the three 2x4s together and make a single cut. The precise angle isn't as important as ensuring that the three legs are all the same. After that, trim the bottom ends of the legs to the length needed for the tripod height you desire. The "DIY Improvements" page of Dave's website (http://eyesonthesky.com) provides a handy table for determining the correct leg lengths for a given platform height.

Next, make the tabletop platform and the spreader. A jigsaw is very handy for these parts, but you can also use a coping saw. The size of your telescope's base will dictate the diameter of the tabletop. It's a good idea to make three recessed holes to accommodate the feet of your scope's base, but don't make these recesses too deep--you don't want the scope's base to end up resting on its center-pivot bolt. Next, drill holes for the threaded rod in the center of the tabletop and the center of the spreader.

Use wood screws to attach the hinges to the tops of the legs and the bottom of the table, taking care to position each leg 120[degrees] from its neighbor. Next, affix the threaded rod to the table with nuts and washers. With the legs extended outward, slide the spreader up the threaded rod and hold it in place with a washer and wing nut. Curved ends on the spreader lobes make it possible to snug up the assembly for maximum rigidity by rotating the spreader.

Dave says the tripod is far more rigid than any of the camera tripods he's tried. The legs fold up easily, and he can carry it and the telescope as a single load.

If you want to learn more about how to build your own SST2, you'll find patterns, detailed photos, and many helpful tips on Dave's website.

Contributing editor Gary Seronik is an experienced telescope maker and observer. He can be contacted through his website, www.garyseronik.com.
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Title Annotation:Telescope Workshop
Author:Seronik, Gary
Publication:Sky & Telescope
Geographic Code:1USA
Date:Feb 1, 2014
Words:638
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