Sooner or later, the stones of the Vitruvian Mill will need to be dressed. When I lifted the Runner back into position I used two 6-metre long, 9” X 3” wooden beams which I brought from home, supported on the top of the wall on the North side and a steel frame I’d made on the South side. This was only ever meant to be temporary, and those beams would pass through where the Horse and Hopper now are. The beams are extremely heavy, and difficult to install or dismantle and put away when not in use. The roof beams are definitely not strong enough to lift the stones which I guess weigh near a tonne each.
So my idea is to permanently install the same pair of beams, horizontally, with ‘legs’ parallel to the rafters of the roof, down to the same bearing point on the top of the North wall, and instead of the metal framework at the South end, something similar, made from old wooden beams saved from a demolished house in Yzerfontein by Hennie Richter and kindly donated to the project. This is one, after the many layers of paint had been removed:
The idea was to saw them up into planks for the elevator, but there are too many nails in them.
The first job was to determine the exact angle of the rafters:
A combination square clamped to the rafter and a level taped to its rule did the trick! 36 degrees to the horizontal.
One doesn’t lightly cut across a 6-metre beam of old imported cold-climate pine, so I applied the rule: Think three times, Measure twice, Cut once! I needed to know that, once the ‘leg’ was cut off, there would be enough wood remaining to reach the wall at the other end. There had to be enough head-room to walk easily under them and I still need to be able to operate the control beam for the trap-door in the launder outside.
I also needed to satisfy myself that the cut would assemble at the correct angle, with the ‘offcut’ turned over:
The join will be the vulnerable point, so I was ‘thinking in chalk’, of all the possible options to reinforce it. I will pin it twice across the joint and strap it top and bottom with thick steel flat bars with tie-bolts between.
I started sanding the as-sawn beams, but it was taking too long, so I used the electric planer first, and soon the rich colour of the old pine came through. The aroma was magic, reminding me of sneaking into the Organ Loft at school, when it was playing!
Using the first as a template, I cut the second:
The difference between the as-sawn wood on the left and planed and sanded on the right is already noticeable. I brought the whole lot home to work more comfortably:
Once the first pair was planed and sanded, I laid the two components out and glued and clamped them together. They’re located with panel pins only at this stage, just to prevent them moving while the joint dries. The glue is more to make the pair more manageable while I drill for the two pins and fix the steel bands top and bottom:
The lengths of the planned steel bands are marked in chalk. I intend to use 60 X 8 or even 10mm thick flat steel bar, bent very sharply.
The second beam is being glued on top of the first, to make sure the angle is the same. The lengths of the steel bands are measured, so the ends of those on the outside and inside are even. I plan to drill two 14mm holes through each joint and tap a 16mm thread right through each, and then screw in a piece of M16 redibolt (threaded rod) with plenty of glue and cut it off at full length, before fitting the bands. It would be nice to use square bar for the tie-bolts holding the bands to the wood, rounded off at the ends for the threads, similar to the U-bolts used on Elim’s wheel:
4th October 2009