Pier base size
- I Am Marsha
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Pier base size
I have a POD observatory that's been on a deck for several years. I'm going to remove the deck and have a cement slab to put it on. I want to put in an isolated base for a pier. How big an area should the cement base be to bolt the pier into?
Thanks for any info you can give me.
Thanks for any info you can give me.
Marsha
Coronado SolarMax II 60mm BF10, DoubleStacked, Cemax EP, Lunt Zoom EP
Zhumell 12" Dobsonian, 'Alien' EQ platform
Celestron NexStar 6 se, 8" orange tube on CGX EQ mount, solar filters, EPs
ZWO ASI120mm, ZWO ASI120mc, ZWO ASI130mm
Skyshed Pod observatory
Coronado SolarMax II 60mm BF10, DoubleStacked, Cemax EP, Lunt Zoom EP
Zhumell 12" Dobsonian, 'Alien' EQ platform
Celestron NexStar 6 se, 8" orange tube on CGX EQ mount, solar filters, EPs
ZWO ASI120mm, ZWO ASI120mc, ZWO ASI130mm
Skyshed Pod observatory
- sdbodin
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Re: Pier base size
OK, I did not isolate my pier base, the pros don't in the big domes either, but rather integrated the base mass into the slab. The base is a cubic yard filled with rebar under the slab with the J-bolts cemented in place to hold the pier. I can have the scope imaging at 8000 mm efl and jump up and down and barely detect a wiggle in the image on the laptop. Of course, I normally just move gently around the scope when imaging, no sense being an idiot.
Clear skies,
Steve
Clear skies,
Steve
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
- KathyNS
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Re: Pier base size
I think mine is a 36"x36"x18" block, with its base four feet down to get below the frost line. On top of that is a 16" diameter column with its top 6" above ground, with J-bolts embedded in the top. A plywood pier column is bolted to the top of the concrete.
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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Re: Pier base size
I live on top of a hill that is all ledge within 12 inches below the surface. That's the depth that I have to work with. If the base of the pier is 12" diameter then is that what the diameter of the footing should be also? Or should I make it bigger? The idea is to separate it from the slab so I won't be walking on it when I'm at my scope.
Marsha
Coronado SolarMax II 60mm BF10, DoubleStacked, Cemax EP, Lunt Zoom EP
Zhumell 12" Dobsonian, 'Alien' EQ platform
Celestron NexStar 6 se, 8" orange tube on CGX EQ mount, solar filters, EPs
ZWO ASI120mm, ZWO ASI120mc, ZWO ASI130mm
Skyshed Pod observatory
Coronado SolarMax II 60mm BF10, DoubleStacked, Cemax EP, Lunt Zoom EP
Zhumell 12" Dobsonian, 'Alien' EQ platform
Celestron NexStar 6 se, 8" orange tube on CGX EQ mount, solar filters, EPs
ZWO ASI120mm, ZWO ASI120mc, ZWO ASI130mm
Skyshed Pod observatory
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Re: Pier base size
If you have bedrock 12" below the surface, then use that as your base. If you can drill into the rock and epoxy rebar into it, then your concrete pier will be well attached to something very, very solid.
The concrete column should be big enough that the bolts attaching the pier to it are well inside the concrete. You want the bolts to be 1" to 2" inside the concrete. So if the mounting flange for the pier is 12" in diameter, the bolts are likely at a radius of 5". So you would want the concrete to have a radius of 6"-7", so a diameter of 12"-14".
The concrete column should be big enough that the bolts attaching the pier to it are well inside the concrete. You want the bolts to be 1" to 2" inside the concrete. So if the mounting flange for the pier is 12" in diameter, the bolts are likely at a radius of 5". So you would want the concrete to have a radius of 6"-7", so a diameter of 12"-14".
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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