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TAPESTRY SUPPORT STRUCTURE by Cyril Granger

Evolution of the Design

At the outset, the embryo Co-ordinating Group considered sewing small individually worked tapestries together to create one large tapestry but this quickly developed to include collages. Initially, it was hoped that approval might be obtained for this large work to be wall mounted in St Mary's Church. However, after local enquiries, the idea was abandoned because it was feared that any delay for approval might jeopardise the timely completion of work to meet the Millennium deadline. Consequently, an alternative arrangement was considered with advice from a group of men co-opted to undertake the design and construction of the support structure. This took the form of a free standing 3-panel folding screen but it was soon rejected due to the size and the likely weight of the individual panels which were calculated to require four women for lifting.

Thoughts then returned to the single large arrangement but using a horizontal bar supported on two vertically mounted posts instead of wall mounting. After considerable discussion this idea was also discarded on aesthetic grounds and also because it was thought that the single piece of fabric would be too large and heavy to handle during assembly. This led naturally to the final arrangement that replaced the single piece of fabric with three separate vertical panels supported between four posts. The outer posts were to be angled towards the viewer from the line of the centre panel. Furthermore, each post was to be free-standing with sufficient base weight to carry the head load safely under all conditions of storage, assembly and display. It was decided that the maximum weight of any individual component of the structure was to be 14 lbs., which is within the safe lifting capacity of the average healthy woman.

Some Design Details

The Co-ordinating Group decided at a very early stage that the support structure should employ durable, beetle resistant, hard wood of mid-tone colour. After looking at a wide range of wood samples a Brazilian Mahogany was selected and used.

The posts were to be nominally 3 inches square with chamfered corners and, for reasons of aesthetics, the bases were to be octagonal in shape. Theoretical calculations indicated that simple wooden bases would not provide sufficient weight to provide stability under adverse conditions. The design criteria chosen for this was that an adult accidentally falling against one of the posts of the structure would not cause the system to collapse. In practical terms this meant that the base width and weight would have to be such that, for a head load of 12 lbs. per post, the system would not topple until the angle of tilt exceeded 35 degrees. This was achieved by using a 14 lb. metal base tray which included a post socket. The metal was to be largely fabricated from angle iron and the significance of the tray was that it was to carry four lead weights, each of about 12 lbs. These were to be moulded from scrap metal to fit the octagonal shape. A total base weight of 62 lbs. was deemed adequate to satisfy the toppling criteria.

The final weight of each fabric panel was just under 4 lbs. and, taking the additional weight of the poles and horizontal bars into consideration, was well within the design assumption of 12 lbs. for the head load. These calculations assumed that horizontal iron bars would be used but ultimately, when the fabric panels could be weighed, it was decided that wooden bars would adequately meet the deflection criteria.

The entire metal base was to be covered by wood similar to that used for the posts.

Source of Main Materials

Wood: Brazilian mahogany from Ternex, Ayot Green Sawmill, Ayot Green, Welwyn.

Lead: Scrap lead from H. Williams, Wallace Way, Hitchin - Lead moulding by men of the support structure team.

Support Structure Team

Dudley Gentle, Barrie Simmons, Graham Gibbs, Geoffrey Welch - sadly, Geoffrey and Cyril Granger died during the project.