There's a few suggestions in the following thread by people who have done their own piers:
https://www.iceinspace.com.au/forum/...d.php?t=213080
My hole is 600mm square and 700mm deep so I could put some gravel and cement powder in to prevent the clay sucking the moisture from my concrete mix and cracking/weakening it when I get to it. The 3/4" rebar is driven in around 1 metre at between 40 and 60 degrees radiating out from the hole at each corner, it should never move. I'm not an engineer (not that kind) so it may not be as solid as I'm hoping but maximum weight will be pier (heavy) pus EQ5 Pro head and a 152mm x 1200 Skywatcher Achromat refractor plus maybe Nikon full frame camera or my 8" GSO f5 Newt and Nikon. The pier is the heaviest part. I think if it moves once installed we've had an earthquake.
I have everything almost ready to go (for too long now) and have had something just come up which is going to keep me occupied for the next few weeks so hopefully late February it will be complete. Then it probably wont stop raining (half of my problem already).
I used to often see mention of 1 cubic metre of concrete, 1x1x1. When I looked into it, that's a LOT of concrete, more than I'm mixing in my wheelbarrow. In saying that my pier is solid and heavy but my equipment isn't, so the pier is over klll but I got it cheap locally and it saved me having to weld my own despite having pipe, plate (up to 1.25") and steel bar ready to go. If I ever get a better mount and heavier gear (finances permitting) the pier will eventually handle it.
