How to build a wheeled tripod

With this ingenious portable base for your telescope, you can observe from anywhere in your garden and cut down on the time it takes to set up.

Written by Dr Peter Wilby.

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Image Credit: 
Peter Wilby

Are you thinking of buying or building an observatory? Well, don’t! At least, not before considering our inexpensive alternative: a tripod mounted on retractable wheels that you can easily move to different parts of your garden to get the best views.

The advantage of an observatory, of course, is that it gives you a solid pier (base) on which to mount your telescope and a permanent home for your equipment. But constructing an observing dome or shed can be difficult and long-winded. They can also introduce unwanted thermal currents, leading to poor seeing, and will obscure part of the night sky.

Building a tripod is much easier and far less expensive. And if the views from your garden are less than perfect, this wheeled design gives you a great deal of flexibility, which can come in handy for following objects in different parts of the sky.

Many tripods are fairly flimsy – they’re built that way so that they’re not too heavy. But while they’re sufficiently portable, a heavy telescope mounted on a flimsy tripod will wobble around like jelly. A heavy tripod has disadvantages too: its sheer weight is a severe disincentive to hauling it out of the box every time you want to observe.

That’s why we’ve chosen to construct our wheeled tripod out of wood. It is, in many ways, the best material for a tripod. Not only is it stiff, light, strong and easier to work than metal, it is also better at damping vibrations. Our tripod is designed around three identical, vertical A-frames, joined together at their lower extremities by small, six-sided plywood footplates. This tripod structure, constructed from triangles, is extremely strong. On top of the A-frames, there is a chipboard platform that the mount head and telescope sits on. Below that, there’s a circular tray for spare eyepieces and other observing or imaging equipment.

The crossbars of each A-frame support a lower plywood platform, which can carry a power-pack or an extension lead with multiple sockets for the various power supply units your setup may need. This can be plugged into the electricity socket indoors, with another extension lead if needed. For safety, it’s a good idea to have an earth-leakage circuit breaker or residual current device fitted to the mains supply you’re using to power your setup.

Our wheeled tripod is carrying a Meade ETX-125, but it would be suitable for telescopes up to 250mm aperture. Bigger telescopes would need a suitably scaled-up tripod with bigger wheels. Here we’ve used 150mm-diameter wheels available from ironmongers and DIY shops.


What you need

Fixings

10mm pivot bolt with two nuts

Three 6mm levelling bolts with six nuts

Wood screws

Three 5mm bolts with spacers and wing nuts

Hardware

305mm-diameter circular tray

Four 150mm-diameter wheels

Matt black acrylic paint

Timber

12x12mm, 34x34mm, 18x44mm, and 44x44mm planed softwood sections

12mm-thick chipboard sheet

6mm-thick plywood sheet

10 and 25mm hardwood dowels

18x240mm disc for plinth (optional)

Tools

Measuring tape

Power drill and bits

Ratchet screwdriver

Set square

Spirit level

Tenon saw and mitre box

Workbench and vice

Observatory deployed

The photo above shows the tripod ready for observing. The wheels have been retracted and the towing handle folded down to make a useful shelf for star charts. The tripod is resting on the points of three 6mm-diameter bolts, inserted through the three footplates to provide fine adjustments for getting the tripod level. If you have patio slabs, you can place the levelling bolts in the gap between the slabs as shown in the photo above. This enables the scope to be repeatedly put in its level ‘home’ position, ready to carry out Go-To alignment. Alternatively, you can mark the position of the footplates to place the tripod correctly for alignment on future uses.

To make the tripod ready to be wheeled around, the towing handle is straightened out, pulled forward and locked in place with two pegs. The rear wheels are lowered by raising the lower rear handle. When raised, the weight of the telescope holds this handle against the tripod without the need for a latch, though a latch can be added for extra security if you need to pull the tripod over a low step, for instance.

In transport configuration, the tripod runs freely on its wheels. It can then be easily rolled away and steered to its home, leaving the garden clear for daytime uses.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 1 - Make three A-frames from 34x34mm planed softwood, with a slant height of 560mm and a base angle of 60º. Brace the top angle with a truncated triangle shape made from 12mm chipboard. Drill pilot holes when screwing parts together, so screws won’t split the wood.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 2 - Make the footplates out of 6mm plywood, then fit the levelling bolts. Screw the footplates to the bottom of the three A-frames, and screw the 12mm-thick chipboard mounting platform on top. Adjust the bolts to level the platform, then lock with 6mm nuts.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 3 - Cut two pieces of 18x44mm softwood 760mm long to fit under the tripod. At each end of these, fit a 44x44mm length of wood across, 202mm long at the front and 372mm long at the rear. The rear 44x44mm bar is screwed, the front one is held with the 10mm pivot bolt.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 4 - Make the front handle and wheel assembly. The 10mm dowel front axle is glued in place, and the front wheels rotate independently on the ends, which project out. Two pegs fitted in the 18x44mm bars stop the front wheels turning too much and rubbing against the tripod.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 5 - Make the rear handle and wheel assembly. Each rear wheel has its own short 10mm dowel axle held between two pieces of 18x44mm wood. The lever action at the pivot makes it easy to lift the 25mm dowel handle against the weight of the scope and tripod.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Step 6 - To make your scope easy to remove, mount it on a wooden plinth, spaced at finger depth above the upper platform and secured with three wing-nuts. Otherwise, secure your mount head with its own bolts fitted through holes drilled in the mounting platform.


This 'How to' originally appeared in the August 2010 issue of BBC Sky at Night Magazine.

 

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