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The first thing I did was to find a good view of the southern and eastern skies. I removed a
cherry tree and had the ideal location to start with construction on the Ash Observatory. My view of the northern skies
is not the best with a moderate sky glow from Philadephia, still I have a good view of Polaris for polar aligning.
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The next step was to start digging the hole for the concrete pier. The measurements are 3' x 3' x 4' deep.
I welded up a rebar cage and placed it in the hole. The 16" diameter sona tube that I used was extended 1' below gound level.
This gave me a massive 3' x 3' x 3' block of concrete below grade with the 16" diameter pier extending 52" above grade. This
gave me a final pier height of 32" once deck was framed and flooring installed.
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Within the form (sona tube) I added a 1" PVC pipe that comes out of the side 6" below ground level and again
at 16" above floor grade. This PVC pipe will be used to run 115v and 12v power over to the pier. No wires running across floor
to trip on.
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Deck was constructed using 2" x 6" pressure treated lumber and is about 12" above grade so no animals will
likely built nests under observatory. Final pier height was established. Note the 1" PVC pipe coming out the side of sona
tube. This will be trimmed once sona tube is removed and will supply the power lines to pier.
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Here I made up a sundial to find true north using the shadow of the sun at transit (solar noon). Constructed
from a scrap piece of plywood with a 1/4" hole drilled thru middle. This same drill bit was inserted in hole and squared to
the plywood. I looked up the transit time of the sun for my location and using the shadow of the drill bit to mark the sona
tube for true north. This mark will be used as a reference mark when placing the pier plate into concrete. You can also
hang a plumb bob above and centered on sona tube and use strings shadow.
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The Readi-Mix truck arrived early Saturday morning. Took all of 15 minutes to pour concrete. I used the
pier plate with the j-bolts attached to place j-bolts into the wet concrete. Using the true north reference mark to align.
I placed to 2 pieces of 2" x 3" lumber on top of sona tube to establish pier plate height. All went very well.
Note: The wooden ring that is inside sona tube was placed there to give last 1 1/2" of pier a 45 degree
angle.
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After waiting 3 days for concrete to cure the sona tube form was removed and the pier plate installed and
aligned.True north for my area is about 11 degrees from magnetic north as can be seen on the compass. My j-bolts are nearly
in the center of the adjustment slots of the pier plate, using Sun's shadow at transit put me right on the money for alignment.
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The 3" diameter PVC pipe coming up along pier and running under floor joist to the back wall is to run video
cables out to the pier. This isolates them from the power cables and keeps them from running across floor being a tripping
hazard. Power PVC tubing can be seen coming out of pier below grade.
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Next step was to apply the floor. I used 3/4" tongue and groove chip board. I cut an extra 1/4" off between
floor and pier to isolate any vibrations being transmitted to pier from floor. This gap is later filled with silicon chaulking.
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After concrete cured for 10 days I couldn't wait to install scope and establish my wall height. Here is
the Meade LX200GPS/UHTC 14" is polar alignment. The wedge used is the Meade Super Wedge.
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With the Meade LX200GPS/UHTC 14" installed it was determined that I could make the walls 5' in height and
still view to the horizon. This height also provided a good amount of wind protection. The walls are standard 2" x 4" stud
construction. Assembled using deck screws, much better holding power then nails.
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Next step was to add the outriggers that the roof will roll out onto. For this I used 2-14' x 4" x
4" pressure treated lumber and 4- 8'x 4" x 4" pressure treated post. I dug out 3' deep holes 12" in diameter at the post locations
and filled to ground level with concrete. Inserted a 16" 1/2" x 13 threaded rod into concrete with about 6" exposed. A nut
and large washer was added to threaded rod. I drilled a 9/16" diameter hole 6" deep in the center of the 4" x 4" post.
The post then slipped onto the exposed threaded rods. With this setup it is easy to adjust for level on the top plates accurately
and if needed in the future for any settling. 2' pieces of 4" x 4" lumber was cut a 45 degrees and added between post and
top 4" x 4" for added support.
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For the roof rolling system, I decided to go with the V-groove 4" rollers. To the top plate on the side
walls I added a 3/16" x 5" steel plate. This plate was first clamped in place, next 1 1/2" angle iron was placed onto steel
plate. Four V-groove rollers were bolted to a 2" x6" for each side. Another 2" x 6" was clamped across the two side 2" x 6"
rails to hold everything together while final adjusts wre made to center everything up. Once everything was aligned and roller
easily a pencil line was used to mark angle iron location on steel plate. Everything but steel plate was removed. Holes were
drilled between the pencil marks and steel plate attached to walls using lag bolts. Next the angle iron was realigned
with pencil marks and welded to steel plate. Frame with V- groove rollers was lifted into place. I'm happy to say it rolls
very nicely.
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With the side walls being 5' tall, I wanted to be able to stand up and work inside with the roof closed.
A total of 12" was added to the roller base frame to give me a rolling second wall of 21". This would provide 6' 9" clearance
inside. Roof framing was added with a 1' overhang all around for added weather protection.
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Ash Observatory is all framed in with the 14"er sitting inside. Getting cold outside so tarps were applied
to frame work for protection over the winter. Sheet metal to be applied in the spring.
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