Piers made from a Highway Light-pole
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
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.
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.
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
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.
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.
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.
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.
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.
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.
materials cost less than $50, for bolts, angle stock and the abrasive
blades to cut them.