Wooden Pattern used to make Steel Parts for the first Suspension Bridges including the Brooklyn Bridge and Golden Gate Bridge

When heavy machinery parts in the Roebling Steel Mill wore out from repeated use, they had to be replaced right away. These parts, including rollers, wheels, gears, were made on site. Steel replacement parts were milled in the machine shop and iron parts were a cavity that has been made in a pliable material such as sand. The cavity is shaped by using a precise replica of the object to be cast, called a pattern.

Pattern making was an unheralded but crucial aspect of making steel. The patterns were made of hard woods so they could stant up to repeated castings and they were made to exacting standards so the parts they turned out were precise duplicates. Pattenmakers were skilled craftsment whose trade bore similarities to tool and die-making and fine woodworking.