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Posts Made By: John Schultz

August 5, 2022 10:50 PM Forum: Home Observatories

My first pier

Posted By John Schultz

wondering how you aligned the pedestal to true north.  I have seen lots of methods but they don't seem very precise. Thanks. 

August 22, 2022 03:54 AM Forum: Home Observatories

Suggestions for a permenant pier before I pour concrete

Posted By John Schultz

I have an MEII and purchased a SB 24" permanent pier.  I have dug a 48" deep by 24" dia hole and will use a  concrete tube to extend the 24" dia concrete about 12" above the ground level (5' of concrete total or about 0.6 yds^3) to allow future observatory floor installation.  I was going to sink J bolts into the wet concrete for attaching the pier.

Questions:
1. as shown in the Software Bisque permanent pier drawing, the slots for the permanent pier are 3/4".  Should I use 3/4" J bolts or 5/8" to allow some adjustment.  I can find 5/8".  Not sure if i can find 3/4".
2.Are galvanized J bolts adequate or should I try to get stainless? These will be exposed to Minnesota weather.  Right now I have 10" x 5/8" galvanized.
3. Any comments on rebar in the concrete?  I inherited 1/2" rebar (long story) and was going to put the rebar in vertically with horizontal members at the top and bottom. Right now I have a rebar frame consisting of 3 rectangles, each about 16" wide and 4' 4" tall and the three rectangles wired together so the outer "diamter" is a rough hexagon. I'll check they fit in the 24" tube tomorrow but probably OK.  Need to lift them off the dirt at the bottom of the hole.   Working on that.
4.Last but not least is 12" above the ground enough - the MEII and Celestron C14 telescope will be OK with the 24" pier height but it is easy to make the concrete taller before I pour the concrete.  Obiously not easy after I pour the concrete :-)  I don't do visual observation.

Thanks.