There are some circle layout jobs that ordinary compasses just aren't suitable for.
A beam compass (or trammel) is much more practical especially when drawing large diameters accurately.
Using a single beam section, the Veritas beam compass deals with circles from 38mm(1.1/2") to 610mm(24") in diameter. Additional sections take you up to 2,030mm(80") for circular tables, rockers, arches, etc.
It has carbide-tipped points that readily scribe metal as well as wood, although the pencil head is usually used for marking out on wood. A micro-adjust feature quickly gives accurate settings. Comes in a fitted wooden case that even includes a small brass centre pivot disc for use where it is important not to damage the work surface. The beams are steel and the fittings are all solid brass.