Wednesday, December 26, 2007

Iron Bridge

The world's first cast iron bridge, the aptly named Iron Bridge was built in 1779 over the river Severn. The designer of the bridge was experimenting with a new material, previous bridges had been made from stone or wood. Construction techniques had not yet been developed for cast iron so the designers looked to wood lore and constructed the arch using dovetail joints and dowels.
The same principles apply in the construction of cardboard automata. Many of the designers of card models come from the world of wood and leather and brass. Boxes are made by constructing pillars from square section tubes and joining these to boards made by folding round card into complex tray like flats. Hinges are constructed with square section tubes rotating in circular holes rather than simple scored card flaps and handles are complex construction of rolled card tubes with multiple tabs joint.
As cardboard engineers we need to understand the material we are using. We need to look at each mechanism afresh; to construct it based on the strengths and weaknesses of the material that we are using rather than fitting existing designs to the material.
Dovetail joints don't suit card.

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