I do love to tinker, and even my observatory is not immune to my attention.  I had spent quite a bit of time designing the original obs, and was very pleased to have it featured in a Sky & Telescope article about “backyard observatories you can build yourself” (Nov. 2004).  The design was a bit short, (48” high) and the lift off roof, while quite functional, seemed a bit awkward.  I have changed the roof to a more traditional roll-off style.  I also wanted to raise the walls a bit to give more head-room, and to block some neighborhood lights.  

I kept the original structure and added 18 inch additions to the bottom of the walls.  I also changed the door from the inward-opening double doors to an outward opening single door.  The doorway is now high enough (68” by 32”) to walk through easily when the roof is closed, as compared to the rather tight duck one needed before.  The top of the door way has a cross-piece now, and one needs to be careful not to bang into it, particularly if you are over 6 feet tall, as I am.  This crosspiece provides a much stronger structure, however, as it braces the walls to either side.  The red “rope light” I use in the interior now crosses the door frame, providing a reminder to duck.

The roof has been refinished with a elasto-roofing paint, providing a better seal.  I also changed the somewhat elaborate interior roof support with a much simpler one.  It is much easier to fabricate and lifts the roof high enough so that it can pass over the walls without lifting.  The single roller of the lift-off model was replaced by 4 castors, 2 to each side.  These castors run on a rail made from an edge-up 2X4 with a flange made of pressure-treated decking stock.  The flange runs on the inside of the rails on both sides, and keeps the wheels from falling off the 2X4.

The castors are not too strong, so when the roof is closed, they rest in slight pockets in the rail.  This lets the roof support settle down upon the wall’s top plate.  The castors only need support the lightweight roof when it is open.  When opening or closing the roof, the front castors simply bump over the indent.  It takes very little effort to move the roof.

When the roof is opened completely, the castors are stopped by blocks of wood at the end of the rails.  Attached to these blocks are pieces of ¼“ aluminum bar stock that fit through the castors and cover the wheels.  In this way the roof is effectively locked open and held down against any sudden gust of wind.  

When the roof is fully closed, it is held in place by two turnbuckles that are attached to the inside walls with an eye-bolt.  The turnbuckles have a hook that pulls down cables anchored to the roof support.  

The higher walls prevent viewing lower than 20º above the horizon, but the surrounding trees and building make that a non-issue.  I am about to install an alcove into at least one wall under the roof supports, as there is little room for shelving in the 7 ½ foot diameter enclosure.  I plan to have the alcove big enough to hold a computer and monitor, as well as reference material and accessories.  The alcove will also shelter it’s contents from dew.

I am quite pleased with this new model, and will likely keep it as is for at least this winter.  Come spring, who knows?
 
     
     
     
     
     
     
     
     
   
 
   
 
   
 
   
Telescope Piers made from a Highway Light-pole
Marc Stowbridge  
[8/3/2005]

 I have a small backyard observatory and, having no desire to trip over tripod legs, I wanted to make a pier.  Looking for suitable material, a friend (actually, his wife) gave me a broken 30-foot aluminum light pole they had in their backyard.  I cut it into 6-foot sections with a reciprocating saw and carted it home.  

Cutting big, tapered stock square with its axis can be difficult, so I built a jig by mounting 2 sets of castors to a 7-foot long 2-X-10.  These cradled the pole and allowed it to turn on its axis against a stop.  I then built a U shaped support out of scrap wood that straddled the pole and held a circular saw with a metal-cutting blade.  By turning the pole under the unclamped saw, I made near-perfect and polished cuts at right angles to the poles axis.  
  
I used a belt sander while the stock was still on the castors.  The belt turned the tube like a lathe and made cleaning and polishing the pier quick and easy.
To make the flanges for mounting the pier, I shaped three pieces of angle aluminum stock I bought from a local boat-dock builder.  I mounted them inside the tube with one bolt, thus preventing them from rotating and kept them quite rigid.  The 5/8” inch holes aligned with 3 imbedded eyebolts protruding 2 inches above the surface of a 5 1/2-gallon bucket of concrete (weight: about 150 lbs.).
  
A plywood circle sits inside the pier, resting on top of the flanges.  This provides a seal for the tube, and can support sand or concrete filling for dampening vibration.  
To level the pier, I put washers under the flanges, resting the pier directly on the concrete base. This reduced vibrations dramatically when compared to putting adjusting nuts under the flanges, and supporting the pier on the bolts.  
To mount the scope to the pier, I cut 6 pieces of ¾ inch plywood into rough circles the size of the inside diameter of the top of the pier.  After gluing them together, I turned the resulting plug on a lathe and drilled out the center to accommodate the ½ inch rod that fits the LX90.  Scopes with smaller bases would need to have the upper-most piece of plywood to be a bit bigger, to act as a flange.  In-fact, this top piece could be much larger, or it could be a cake pan like the one pictured, providing a very handy eyepiece and accessory tray.

The plug mounts under the scopes base, just as if one was putting it on the tripod.  The plug is then secured to the top of the pier with threaded knobs.  
I have made piers for a C-11, LX90, a 10” Newtonian and a C-8, both on a GEM.  If the scope bolts to something, it likely can be accommodated by such an arrangement.
        
This plug is for a Super Polaris G.E.M.  A screw on the side of the plug fits a notch in the pier.  This screw, once installed when the scope is aligned, lets one replace the plug in the same orientation, preserving one’s polar alignment.
The materials cost less than $50, for bolts, angle stock and the abrasive blades to cut them.