The Octagonal Observatory

Base Detail

Decided to make a few changes from the grand plan:

1. The corner joints are less fancy - straight diagonals rather than the two cuts:
   
2. Attached the centre supports at 45 degrees to the two base boards rather than in line. I guessed that this would be stronger but in the end needed to add an extra support in the middle:
   

The cross-over joints were fairly straightforward - set the circular saw to the right depth and then drilled a hole for the jigsaw to cut across (couldn't figure out how to do the plunge cut).

Screwed all the base supports together and to the base boards with decking screws.

The base supports are 24" met-posts - rather than drilling holes and using concrete. Why? Quick and easy plus I'm putting the observatory on top of an old tree stump (tried digging it up but the roots are everywhere). If these foundations are not good enough I can easily replace with concrete and bricks.

I've put fence posts high enough to clear the stump and mounted the base. It's rock solid at the moment (I've jumped up and down on it and I'm no lightweight! - 120kg).