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Equipment Discussions >> Observatories

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musicos
member


Reged: 06/16/10

Pier for rooftop observatory new
      #5670823 - 02/09/13 02:04 PM

Hi, I want to put close to 800lbs of gear (mount, photographic newton,...) on a pier 13.5' above ground. Ground is hard clay. We live in southern France, there is close to no frost zone. I wonder if it would be better to dig a deep foundation, or a large foundation. Also, I wonder about the dimensioning of the pier. I thought about a foundation 5x5', 3' deep (but I could do also 4x4', 5' deep). Then, a concrete column up to 8' above ground (size 2x2'). Finally, a 6' steel column, bolted on the concrete column, diameter approx 1', filled with sand. There are also ideas about building an enormeous tripod (or quadrupod), out of steel parts, from ground to top ("Eiffel tower"), or building a brick chimney and filling it only with sand (but how to fix the mount on it). My major issue concerns vibrations. Also, if I could find a solution which might be dismountable one day would be nice, but that is second priority. My observatory will be at the end in the 3rd floor of the atelier of my wife (who is a painter). I'll have to insulate it very well from heat influences...
You see, many questions, I'd be more than happy to get your different ideas and opinions.

best regards and a nice weekend

Torsten


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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: Pier for rooftop observatory new [Re: musicos]
      #5670905 - 02/09/13 03:19 PM

Quote:

Hi, I want to put close to 800lbs of gear (mount, photographic newton,...) on a pier 13.5' above ground. Ground is hard clay. We live in southern France, there is close to no frost zone. I wonder if it would be better to dig a deep foundation, or a large foundation.

Torsten




They have been building stone fireplaces and chimneys for thousands of years in your part of the world. Many of them are still standing. Some not to far from where you are.

Talk to the people who do the building. Any one of them will know more about what to do in your area than the entire CN group knows collectively.


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rimcrazy
sage


Reged: 03/03/12

Loc: Overgaard, AZ
Re: Pier for rooftop observatory new [Re: musicos]
      #5670950 - 02/09/13 03:56 PM

This is my custom pier.



It is on a 5'x5'x3' concrete block. The base is 48" in diameter. The height is 9.5' from base to the top. I plan on putting a 450lbs of telescope on top of this ( 20" PlaneWave with a AP1600 GTO mount). The base weight is over 12,000lbs.

A few qualifiers here. This is an imaging observatory only. Obviously with an eyepiece over 10' in the air, I'm not sitting around looking through it. I have access to custom metal fabrication. (My son is a ME with his own metal fabrication company. This helps A LOT!) The raised round concrete pier that you see is actually not by design, more evolution. This started out as a ROR observatory and morphed to a dome. With a ROR, a much shorter pier was too be bolted to the round concrete pier. Now it's just ballast. The level of the floor is actually the top of what you see as the round concrete pier. There is a 18" to 2' stem wall around the building. There is insulation between the floor and ground to keep the concrete slab thermally more constant.


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stmguy
sage


Reged: 10/11/12

Loc: Western NH
Re: Pier for rooftop observatory new [Re: rimcrazy]
      #5671981 - 02/10/13 08:57 AM

I would go with a concrete block pier for something that big..see Brian Lula's obs in New Mexico..scroll down
http://www.heavensgloryobservatory.com/observatory.htm

Norm


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csa/montana
Den Mama
*****

Reged: 05/14/05

Loc: montana
Re: Pier for rooftop observatory new [Re: musicos]
      #5672099 - 02/10/13 10:25 AM

Welcome to Cloudy Nights, and especially the Observatory Forum!

Rest assured; you will get many helpful suggestions from our great members here, that have built something similiar to what you are considering. There's a wealth of information here from our kind members that love sharing it with others. Members here have a lot of experience, and gladly share it; so keep asking questions, and our gracious members will help you along.


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1965healy
The Snarkster
*****

Reged: 06/23/07

Loc: San Antonio, TX
Re: Pier for rooftop observatory new [Re: csa/montana]
      #5673140 - 02/10/13 09:50 PM

http://www.cloudynights.com/ubbthreads/attachments/2314126-DSC00740.JPG

Concrete block pier for my Obs. Roof top ROR by BYO. The pier is about 7' tall, filled with cement and rests on the concrete slab of the garage. There is a steel pier bolted to the top where it is level with a hole in the Obs floor.
You could contact Scott at Back Yard Observatories and he might be able to recommend the proper dimensions for your application.


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musicos
member


Reged: 06/16/10

Re: Pier for rooftop observatory new [Re: 1965healy]
      #5674399 - 02/11/13 04:39 PM

Hi, thank's for all the comments!
I won't ask Back Yard, he's asking for money for advice. No good. I like the idea of a sand filled pier...but how to do the top plate ...

Torsten


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Raginar
Post Laureate
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Pier for rooftop observatory new [Re: musicos]
      #5674435 - 02/11/13 04:51 PM

Perhaps paying for advice isn't a bad option. He's got lots of professional experience in it.

How do you do a top plate? Honestly, I bought one. The bottom plate I made out of wood. My plate ties into a wooden pier so it's lag bolted in... if you were setting up a concrete pier you would put j-bolts in and create a steel plate around that.

Top plates are harder to make.. I'd recommend googling them and just paying for it.


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musicos
member


Reged: 06/16/10

Re: Pier for rooftop observatory new [Re: Raginar]
      #5674485 - 02/11/13 05:17 PM

Hi Chris,

I give advice for free, so I don't pay for any advice. Btw, I'm a professional astronomer, and I never had the idea of asking for payment... of any kind from amateur fellows...!

To do the metallic work of a topplate is not easy, but not really difficult. The hard work is to link it correctly to the pier, and if the pier is made of sand, it's even more tricky...

Torsten


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csa/montana
Den Mama
*****

Reged: 05/14/05

Loc: montana
Re: Pier for rooftop observatory new [Re: musicos]
      #5674549 - 02/11/13 06:01 PM

Quote:

I give advice for free, so I don't pay for any advice. Btw, I'm a professional astronomer, and I never had the idea of asking for payment... of any kind from amateur fellows...!




FYI; Scott has graciously offered advice many, many times on this forum without asking for payment, as he is also an astronomer & member here. His expertise has helped many here!


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Scott Horstman
Vendor - Backyard Observatories
*****

Reged: 03/11/04

Loc: Here, There and Everywhere
Re: Pier for rooftop observatory new [Re: musicos]
      #5674590 - 02/11/13 06:31 PM

Quote:

I won't ask Back Yard, he's asking for money for advice. No good





I don't know where you get your information but many here can verify that I've never asked for a bleddy cent to help folks out if I can.


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*skyguy*
Carpal Tunnel
*****

Reged: 12/31/08

Loc: Western New York
Re: Pier for rooftop observatory new [Re: musicos]
      #5674617 - 02/11/13 06:53 PM

Using concrete blocks makes a strong and very cost effective way to build a tall pier. I built a 14' chimney block (16"x16"x8" blocks) pier 12 years ago for my 12" SCT ... mainly for astrophotography. I have about 140lbs. of equipment mounted on the top ... not 800lbs. ... but my pier has been proven to be very capable as a photographic platform.

Observatory and Pier

Pier Cap

12" SCT on Pier


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mikey cee
Postmaster
*****

Reged: 01/18/07

Loc: bellevue ne.
Re: Pier for rooftop observatory [Re: *skyguy*]
      #5674814 - 02/11/13 09:12 PM

Maybe Musicos believes there would be a conflict of interest asking a vendor for "free" advice. He probably feels awkward being that forward with someone who makes a living doing this sort of thing. Hell I don't know. Mike

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musicos
member


Reged: 06/16/10

Re: Pier for rooftop observatory new [Re: mikey cee]
      #5675175 - 02/12/13 02:13 AM

@ Scott. Sincere apologies! I (mis-)understood from a too quick reading of your webpage that your offer concerns astronomy shag building advices (for purchase). Now I went back on the other pages of your site and discovered all the BYO observatories you propose, and they are really very nice!

Edited by musicos (02/12/13 02:33 AM)


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csa/montana
Den Mama
*****

Reged: 05/14/05

Loc: montana
Re: Pier for rooftop observatory new [Re: musicos]
      #5675768 - 02/12/13 12:39 PM

You may be referring to Scott's very detailed plans (blueprints) for observatories. These are on paper & sent to those buying them; much different from advice.

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musicos
member


Reged: 06/16/10

Re: Pier for rooftop observatory new [Re: csa/montana]
      #5676126 - 02/12/13 03:48 PM

I would like to come back to the question of the pier... :-))


Edited by musicos (02/12/13 03:50 PM)


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Mary B
Vendor - Echo Astronomy and Electronics
*****

Reged: 05/21/10

Loc: Minnesota
Re: Pier for rooftop observatory new [Re: musicos]
      #5676240 - 02/12/13 04:40 PM

I have read much of scott's advice that has been posted in this forum, it really should be compiled into a sticky.

With that much weight I would consult an engineer but a poured column would work.


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Scott Horstman
Vendor - Backyard Observatories
*****

Reged: 03/11/04

Loc: Here, There and Everywhere
Re: Pier for rooftop observatory new [Re: musicos]
      #5676241 - 02/12/13 04:41 PM Attachment (19 downloads)

We've always done them like 1965Healey's link. Preferably with a base as shown in the picture below. An isolated base can be poured but we've found that going right to the existing slab is fine.
In the picture the rebar was added right into the fresh pour and the ground was scooped out so the concrete there was a couple feet thick. You can use wedge anchors with steel added to help hold the block to the floor and once you get the whole thing poured solid, it's not going anywhere.
Another thing I like about using block is that you don't have to worry about doing a continuous pour (just add rebar at the joint) or the form blowing out.


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musicos
member


Reged: 06/16/10

Re: Pier for rooftop observatory new [Re: Scott Horstman]
      #5676267 - 02/12/13 04:51 PM

Hi Scott, and thank's for the advice!
I have the situation that my original slab is only 4" thick.
I will therefore have to cut out the existing slab, dig in depth, etc....I did not know beforehands that I would one day
construct a rooftop observatory at this place!

best regards and thanks
Torsten


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Scott Horstman
Vendor - Backyard Observatories
*****

Reged: 03/11/04

Loc: Here, There and Everywhere
Re: Pier for rooftop observatory new [Re: musicos]
      #5676380 - 02/12/13 06:10 PM

I won't say that digging a 3'x 3' hole wouldn't be better but a 4" slab is generally 2500psi so technically if you did a 32"x32" block column right on the slab, providing your fill is solid, you can have 256,000 lbs (if I'm doing the math right, it's been a long day, someone correct me if I'm wrong) sitting there with no worries.

Back in the day we used to run block service chimneys from the basement up through 2 floors and out the roof and those sat right on the slab.


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