The Foundations

Having gathered the materials it was time to start.  First I built the two metre diameter decagon I decided on in the design phase, then I called on my neighbour.

My neighbour is a landscape gardener (I find it very useful to have friends who can do Things, as we shall see later in the project!) and coincidentally he had rented a mini digger and an auger for his own project and agreed to help out and dig the foundations for me.  Here he is scrapping the vegetation cover off the building plot:

Once the ground was cleared we marked out the position of the supporting piles and the centre point for the pier and then dug them out with a hydraulic auger (in the background you can see the decagon propped against the hedge).

Interestingly we found that the auger easily lifted large rocks out of the holes but would jam when it encountered a pocket of smaller fist sized rocks.

Having dug the holes we then filled them in again!  This time with concrete and some fence posts which were too warped for Martin to use in his work.  And here it is:

Here we can see another consequence of choosing the decagon over the octagon.   Due to the un-compacted nature of the soil and the inherent inaccuracy of the machinery we couldn't get a post under each joint in the ring, instead we had to go with every other joint which is less than ideal as it allows a lot more flexure in the bearer ring and a lot more stress on the unsupported joints, hence the reenforcing plates you can see sandwiching each joint top and bottom.  Had I built an octagon we could have had a post under each corner and a lot less faffing about with the joints (but even now I still hadn't realised the real problems that lay ahead in using this shape).  But nevertheless we have reached a milestone, we were out of the ground!

The central pier is worth talking about, in total it was two and a half metres long, of which a metre is buried in the ground.  We cut slots in the side and placed reenforcing bars through these slots and then poured about two thirds of a cubic metre of concrete into the pit making sure it went into the tube through the slots, once up to the level of the ground we poured more concrete into the tube to fill the inside to the same level as the outside.  Safe to say this pier is not going anywhere anytime soon.   Once the concrete hardened we had some fun playing tubular bells on the pipe, but since vibration is a very bad thing in a telescope mount I then filled the pipe with sand and grit to damp down the ringing to a dull thud when tapped.   The final touch was to skim some fine cement over the top of the concrete block and summon the family.

All hail the mighty pier!

The foundations are done! Onto the next phase.