Pier sizing assistance please

[Eruliaf]

Good afternoon all,

I am in the process of moving house and have had 'approval in principle' for a small observatory in our forever home. I am still in the planning phase of this, as I would like to ensure that it takes up the least space possible (looking at rotating or hinged roof options as opposed to ROR, although all much lower in priority than actually moving), however I have been offered an opportunity for a fabrication workshop to make me a pier from mild steel pipework (material as per attached image). This is typically used for water distribution systems and comes in a variety of sizes/thicknesses. I appreciate that the bigger the better (diameter) for stability, but to big would not be practical. I was thinking that 200mm dia would be a good compromise (available in 100, 150, 200, 250, 300+ mm dia). For reference, this is quite sturdy, the 200 mm dia is around 25kg per metre of length. I will request that this is fitted with flanges at both ends - one to allow fixing to a base and the other to a plate which will then have suitable holes drilled to fit an adapter plate for my HEQ5 mount.

So, the question is, with my current scopes (200P and 130PDS SW Newtonians) - what length of pier is required to retain the mount at a reasonable height for visual and photography use? What else should I be considering with this?

Thanks in advance

[fozzybear]

6" or 150mm  external around 168mm and a height of - 1050mm high would do with a tube wall of between 4mm and 4.5mm. those flanges in your picture are not cheap around 70 quid a go maybe go with a flat piece of steel at either end to cut down costs

[fozzybear]

have a gander at this video as well might help you

https://www.youtube.com/watch?reload=9&v=AOeLnecOMeg