Last updated on
4/11/
2006

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A Pier You Can Build
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If you get deeply involved in astrophotography, at some point you will want a permanent pier upon which to mount your scope.  This has the advantage of “freezing” the polar alignment of your scope; when you carry your scope out to the permanent pier you won’t need to do another time-consuming polar alignment before starting to take photographs. (Note: if you’re not in a situation where you can mount a permanent pier, you might find it useful to make a dolly to move your complete scope and tripod assembly out from its storage location to your observing location.  Duane Deal has a nice modified dolly shown on the equipment page of his Macintosh Astronomy web site.)

You can make a permanent pier out of wood, metal, or concrete. It’s hard to say which material is best - from what I can tell any one of these options works better than a standard tripod, and is certainly easier to walk around at night without tripping over a tripod leg.  Note however that a hollow steel pier does not damp vibrations well unless the tube has a thick wall - it’s best to fill it with concrete.  I’m contemplating building my pier out of pressure-treated wood because wood damps vibration well, it’s easier for me to work with wood, and I live in an arid climate.  After installing a pier, your only other requirement is to purchase an equatorial wedge that remains permanently bolted to the pier and thus remains in permanent polar alignment. 

Here are some Links to help you design a pier for yourself:

Wood
Sunny Choi’s Pier
Leo Taylor's Wood Pier
Bill Arnett's Temporary Pier (note that he didn’t set his wood pier in concrete - he just backfilled it with dirt - and says it isn’t very stable. Set a wood pier in concrete just like a steel or concrete pier, and then its stability will be just fine.)

Metal
Chris Heapy’s Telescope Pier

Concrete
Andrew Cooper & William Lofquist’s Backyard Pier
Bert Katzung's Pier

If you decide to make a pier, you can easily make a top plate on which to mount your scope’s equatorial wedge.  Get a 3/8” thick, 8” square aluminum plate from McMaster-Carr or OnLineMetals.com; aluminum is a soft metal and easy to work.  Drill and tap the three 5/16”-18 holes in the plate for the three mounting bolts for your wedge. (The proper drill for a 5/16”-18 tap is a ‘letter F’ drill, but a 17/64” drill will work for the tap hole.)  If you use a Celestron wedge, you also need to place a 5/16”-18 bolt up out of the bottom of the center of the pier top plate, about which the wedge rotates when you make the incremental axumuth adjustment for polar alignment. If you plan to mount the top plate on a wood pier, drill and counter-sink a number of holes in the top plate for flat-head wood screws. Use a belt sander to round the corners of the top plate (a belt sander works just fine on aluminum), and an orbital sander to finish it. You can spray-paint it for a durable finish - be sure to screw (sacrificial) 5/16”-18 bolts into the holes you tapped before you spray-paint the top plate, to keep paint out of those holes.

Here’s a photo of the pier top plate I made for myself, with 2.5” long #12 brass wood screws in place, to mount it to a wood pier (perhaps more screws than are really needed <g>).  I’m using Jim Mettler’s wedge which uses a different pivot arrangement than the Celestron wedges, so I don’t have a center hole in my top plate.


 

Important information for do-it-yourselfers:
The threaded holes in the base of the Celestron fork mount, that mount the scope to the Celestron wedge, are 3/8”-16 threads. The threaded holes in the top of the Celestron tripod, to which you mount the wedge, are 5/16”-18 threads.
 

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