Backyard Observatory project

Project Steps

  • Planning
    • Include de-commissioning strategy
  • Building Permits
  • Pier
  • Deck
  • Enclosure

Decisions Needed

  • Pier construction: concrete or steel
    • Need to initiate purchase if steel & seek cheap shipment opportunities
    • Also affects choice of pier-to-head mounting adaptor
  • Height of platform above ground
    • Try to clear snow cover and gain hedge clearance
  • Dimensions of platform
    • Trade-off room for enclosure with visual impact on yard
  • What to do about power
    • Permanent exterior conduit or just a convenient extension cord?

General Concepts

  • Pier-mount G11
    • Height suitable for SCT and refractors
    • Concrete-mounted pier
      • Commercial steel pier in concrete, or concrete pier?
      • DIY concrete
      • Some commercial options
  • Cedar deck standing surface surrounding pier
    • Height of deck chosen to:
      • (With pier height) raise scope someone to improve horizon over hedge
      • Raise surface above normal snow cover depth to facilitate Winter work
  • Eventually, cover with SkyPOD
      • Something like this (from skyshed gallery):

Deck Design

Dimensions need to fit the eventual dome.

Dimensioned overhead view of 3-bay dome:

  • So, minimum dimensions of deck 120″ by 140″, but I’m going to use 140″ square to allow movement for offseting pier in North-South direction.
  • Top of Pier 40″ above deck surface
    • Note that my original target height was 48″ since this is equivalent to the height of the tripod. Wayne at Skyshed recommended against this for both convenience and stability — he says they rarely go above 40″. I am going with his recommendation, knowing that I can always add a pier extension if more height is needed.
  • Pier location on deck?
    • Offset approx 10″ from centre of dome to allow zenith view
    • Horizon opposite the pier offset suffers, so offset pier toward North since Southern horizon is blocked by house anyway

Pier

Decided on “SkyShed Pier” — steel pier to be concrete mounted. Corresponding with owner Wayne I settled on their largest — 8″ in diameter. It arrived a couple of weeks after ordering. Wayne suggested ordering a Losmandy G11 Pier Adaptor rather than having them make a custom G11 mounting head — it would work as well and be a little cheaper.

It’s big and very sturdy. Heavy enough to be hard to lift. The bottom is drilled with 4 holes for securing to concrete.
There is a heavy adaptor plate that fits on the top and is rotateable. 3 side bolts will secure it against the pier once rotated into position, and 3 long double-nut bolts between two sectioins allow for leveling of the top surface.
To mount the G11 head, the top plate will hold a Losmandy G11 Pier Adaptor. The holes in the top plate didn’t match the adaptor, so I drilled a few extra in the right spot.
The adaptor is secured with a main centre bolt and several counterbored socket screws.
The bottom will be secured to concrete by J-bolts set in the concrete. To establish their spacing and hold them while the concrete dries, I made a wooden form drilled where the holes in the pier base are. The form will sit in the concrete this way, with the heads of the bolts up. The 1″ thickness of the wood will prevent the bolts from sinking into the concrete too far.
The J-bolts are just 8″ long bolts bend at the end.
They will be pushed into the wet concrete of the pier footing and the “J” section prevents them from being pulled out once the concrete sets.

Journal

July 20, 2009
I’ve decided to use a prefabricated SkyShed Pier, concrete-installed to sit flush with a low deck. I wrote to SkyShed seeking prices and advice on pier size. Overnight I received a reply from Wayne, recommending the 8″ pier and giving  templates and photo-instructions for the footing installation. He advises targeting pier height of 40″ above the raised floor, not higher.
July 20, 2009
Last year we had our sundeck rebuilt and I was very impressed with the workmanship of the contractor, K-Deck, who did it. And very impressed with how hard it was to dig the holes for the concrete footings in our rock-laden soil. So I expect digging the footing for the pier to be a major bit of work. To help plan and budget, and to convince myself to do-it-myself, I’ve written to him for a quote on having him do the whole job (footing and deck) and having him do just the concrete. I estimate it’ll be about $8000 for the whole job (which will convince me to do it myself) and under, but near, $1000 for the footing. Then I’ll get prices on concrete, tubing, and renting suitable tools for do-it-yourself, and make that decision.
July 23, 2009
Calculated dimensions for pier offset (and some flexibility) and sketched layout of deck. Posted in the Yahoo group a question testing my assumption about offsetting the pier toward the South.
July 24, 2009

Repies on the Yahoo group indicate I had the offset wrong — with a Southern blocked horizon, I should offset the pier toward the North, not the South.

Mike of K-Deck responded he’d be happy to do either the whole job or the concrete, and is coming on the weekend for details.

July 25, 2009
Mike K visited. He’s going to do 3 levels of quote:  (1) just the central concrete pier; (2) also the deck, done on surface-mount deck blocks; and (3) full job including proper concrete footings for deck.
July 28, 2009
Received quotes on various degrees of professional help, and the prices were better than I expected.  I believe I’m going to have the pro do both the concrete for the pier and the surrounding deck.
July 30, 2009
Ordered SkyShed Pier — 8-5/8″ diameter (their widest), 40″ tall, with G11 collar and concrete base.  Response from Wayne said two to three weeks.  Also he sent the template for the wood form for the base mount, so I can build the base in advance.  I won’t do the concrete work, though, until the real item arrives — I’d want to verify that the template matches the real base.
August 1, 2009
Wayne at Skyshed says before end of Aug for Pier delivery. Contacted Mike at K-Deck to get in queue for deck construction for September. Purchased some plywood and J-Bolts at Home Depot to make the J-bolt concrete jig before work begins. (Need to finish cleaning up flood mess in workshop first.)
August ??, 2009
Pier delivered — see images above. Made wood form to hold J-bolts while concrete sets. Drilled pier top plate to match holes in Meade Field Tripod Adaptor.
August ??, 2009
Signed contract & paid deposit to set pier and deck construction in motion. Estimated start date is end September.
Oct 1?, 2009
Started a separate web site for the observatory — take up the log and construction progress there.

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