Jump to content


Another request for Pier design guidance.....


Recommended Posts

Hi all,

There've been a number of recent posts about pier design, but I'm struggling to find the information I'm looking for and, rather than hijack someone else's thread, decided to post afresh.

I'm at the very early stages of obs design, mainly due to current cash-flow constraints, but planning ahead is good fun and will hopefully result in a better design, rather than making it up once construction has started!

I've been able to acquire a couple of lengths of galvanised spiral air-con tubing, which I plan to use as the basis for a concrete filled pier. The tubes are of different sizes and I'm struggling to know which would be best suited. I'd be grateful for advice from others who've used similar designs.

The tubes diameters and lengths are:-

6" x 6'6"

11" x 4'3"

I hope to mount an EQ6 on the top, to hold a 10" newtonian.

My dilemma is -

1. The 11" would be really solid, but the length means I couldn't sink it very far into the concrete base without losing vital height. Is this likely to be a problem? The other consideration is - might the mount/tube fowl on the pillar in certain positions.

2. The 6" is plenty long enough to embed in the base block, and would not cause fowling problems with the mount/scope, but compared to the 11" it looks very thin. Would it be strong/rigid enough?

Any advice would be really appreciated.

Needless to say, when I eventually do start the build I'll be posting lots of lovely piccies.



Link to comment
Share on other sites

Not sure if you have seen this thread of mine:


Might help to shed some light, the link to the CN article makes interesting reading!!! Basically depending on the height the tube diameter will vary and this will vary depending on the chosen deflection arc seconds you want.

Based on this article I ended up with a 12" diameter pier which seemed very chunky, especially given other piers that I had seen. So I decided to do some more research and ended up settling on a 200mm diameter pier (8").

As said above, the 6" should be suitable for what you want given it is going to be a concrete pier. Based on that can you not cut the tubing down in length?


Link to comment
Share on other sites

If its being filled with concrete it doesn't matter how much or little is sunk in the ground its only holding the concrete firm until it sets, make sure you have some steel rod/rebar up the full length, a piece of scaffolding pole hammered into the ground would be good.

Mine is 10 inch in diameter so your 11 inch will be fine.






Link to comment
Share on other sites

Mine is 10 inch in diameter so your 11 inch will be fine.

Thanks George. Beautiful mount you have there. Great to see the pics of the build also.

With a wide pier, one of my worries is that the OTA may hit the mount when passing the meridian when pointing to the zenith. Is this ever a problem?


Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.