The post below is most informative on the subject of pier design.
http://www.iceinspace.com.au/forum/s...d.php?t=132544
The nett conclusion is that large diameter steel pipes with gussets as described by Avandonk and bolted down as described by him are best.
With this in mind my pier will be 9 inch diameter steel pipe with 10 mm wall thickness and will be 4 feet tall, the gussets are planned to be 3 feet tall.
The main unresolved design question is the reflection of vertical vibrations from the mount back into the mount at the top of the massive pier.
My neighbour, who is fabricating the pier has so far made the 25 mm thick base plate and drilled the holes, placed at Avandonk's suggested places.
He has volunteered that he can machine an internal taper in the pipe, starting at the top of the gussets and reducing to a wall thickness at the top of the pier of 5 mm.
My question is, is this likely to reduce the vertical vibration reflections?
Also, is it likely to introduce other unwelcome dynamic effects?
Chris