As I wrote in a previous post, I have been using the expertise of Simon Butler, our brilliant metalwork technician at Bath School of Art and Design Bath Spa University, to advise me how to construct the mechanism that will enable to sculpture to spin.
As per Simon’s advice, I have bought two lengths of metal pipe – one to go inside the other – and two bearings with a three inch bore which will fit over the wider of the two pipes. As the larger metal pipe is 3 inches in diameter and the inner bore of the bearings is also 3 inches it will be too tight a fit so Simon is using the metal lathe to shave 1 to 2mm from the inside of the bearings.
When I ordered the metal pipes I asked for one to fit snugly into the other only to be told that they are not designed for this so there is a 6mm to 7mm difference in the bore of the 3 inch pipe to the outer diameter of the smaller pipe. So that they fit one inside the other better we are welding three lengths of flat metal section along the 3 meters of the narrower pipe.
This, below, is the point where the two 3 inch pipes will meet. The section on the left is 125cm and will be sunk vertically into the ground and the 200 cm section on the right will mostly be inside the sculpture except for 5cm which will extend below it so that the sculpture does not drag on the ground.
The bearings will be mounted onto the 3 inch pipe approximately 155cm apart.
The bearings are too stiff as they are not really designed to spin so Simon has removed the rubber seals that hold in the grease and they are now spinning well. As they will be well greased, secured inside the sculpture and running at low speed, we are not expecting the removal of the seals to be an issue.