chapter  15
Making and Fixing Arch Centres
Pages 7

Figure 15.1: A beam compass or a radius rod is required to set out the full-size shape of the centre, either directly onto the rib material (single and twin-rib) or onto a hardboard or similar setting-out board (four-rib and multi-rib centres), from which a template is made of the common rib shape. The beam compass consists

a radius rod can be easily made, consisting of a timber lath with a panel pin or nail through one end, the other end drilled to hold a pencil firmly.