During the week, I took my learning experiences from last Saturday and continued building and improving the jig.
I still hadn't finished by Friday evening and had to complete some of the jig construction out on site on Saturday.- mainly the head attaching to the square extension.
The first column near Ian's side went in uneventfully even if it was a slow process.
With the jig in place and accurately set up I was able to drop a plumb bob down to mark the column position on the screw pile, measure the length, cut and tack weld while clamped and eventually prop the column up with some scrappy timber I brought with me.
At the end of the day I had to find the energy to reattach the roof edging.
After a leisurly start the next morning, I was out on site again.
This time I ground back the new screw pile cap and welded it in to position.
I put a lot of care in to the welding and ended up with a good clean result.
Then I needed to build two right triangles with the left and right hand jigs.
I found that there were a number of problems with the stands I was using (pipe in to umbrella stands, with angle iron clamped on).
Firstly it was very difficult to unclamp, lift the angle iron with the load on top, stop the angle iron falling away, and reclamp.
Secondly, there was not a sufficient safety landing zone on top of the support and on a number of occassions the 3m arm simply fell off the stand.
Eventually I was to the point where I had both triangles set up and then just needed to lift in place the extension square.
This proved to be a time consuming job as the square was heavy and fragile - I needed to gradually walk it up the two A frame ladders.
Just when I though I was almost ready to measure up the corner steel, I heard the whole structure fail above me as I made a small adjustment on one of the stands.
I scrambled out frantically to avoid being hit by pieces of falling steel.
A number of the components of the jig were bent and I felt like giving up.
After cleaning all the debris away I still needed to spend about 45 minutes attaching the roof edges again in the gathering gloom.
After some reflection over the next day I realised that the majority of my problems was caused by the stands I was attempting to use.
On Monday morning, the first day of a week off that I am taking, I went to see "Jonny English Reborn" at the cinema and then visited the Midland Bunnings.
In the gyprocking secition of the trade department I found some adjustable 3.9 metre telescopic stands capable of taking a 30 Kg load.
I will give these a try next
Armed with my new telescopic support arms I had another go at errecting the jig.
Before I could start I needed to spend an hour or so fixing up the bent and damaged components of the jig.
I also realised that without the hypotenuse piece, the 4m are would be completely unstable sitting on the new support arms (they can pivot at top and bottom)
I realised that I need a rigid safety support arm, fixed at an approximate height, to stabilise the jig until all the components were bolted together.
I could then use the fine adjustment on the telescopic arms.
This all went pretty well. I only had one small collapse at one stage while I was attempting to lift an hypotenuse in to place - this left me with a chunk of skin grazed out of one hand (still smarting today).
I had also learned from my mistakes last Sunday and changed my procedures somewhat for installing the corner square part of the jig.
As a precaution, I checked out the height of column needed using the laser level as well.
The physical jig height and the laser height agreed to within 2mm which was very pleasing.
I tack welded the column in to position and as night fell, I propped it up with timbers and took down the jig.
I packed up in the dark and left about 8.00 pm.
So far it has been a very slow process using the jig but now that I have established the difficult column, I am hoping that this Saturday I can install the remaining 5 columns on the back veranda relatively quickly.