Rally,
Seeing that pier and scope mounting systems are a hobby thing and there are no actual building standards to go by, I can only make my comments from personal experience.
My pier was put in as a temporary quick fix and is very light weight in comparison with most that I have seen on this forum. Minimal concrete used , but my ground is hard compacted sandy loam. Top plates are 8mm thick and rat cage bolts 10mm. The only vibration spike that I have been able to detect is when the dog has barked next to the pier, the walls of my pier tube are too thin and sharp noise resonates there. I have since constructed a shorter pier with a thicker steel tube that doesn't seem to have that issue. Considering how many people here have rats cages as part of their pier that there would be more comments about their unsuitability for the purpose? The weakest link still is the single central bolt holding the mount and scope down.
Quote:
Originally Posted by rally
Rick,
The strength requirement of a pier is the easy part of the pier design, and what you say is true.
But the other main function of a pier (at least for astrophotography) is also to transmit any and all movement and vibration to the ground, that requires much greater rigidity, which has the unnecessary byproduct of being over engineered as far as strength is concerend.
So there is a point to it, but its not for strength.
Of course if there are weak links in the chain - eg rats nest on little M12 threaded rods, mount backlash and high PE then the quest becomes less useful, but its all about progression, so building the cheapest part of the system (pier) to be a strong link rather than a weak link makes sense as you are only arguing about loose change by comparison.
Maybe $50-100 or less and a bigger hole = more labour !
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