Shoe last machining using virtual digitising

Shoe lasts are the moulds used in the footwear industry in order to mount the shoe. Moss of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived in the shoe last market but their accuracy and efficiency is no better than traditional machines, and so it is difficult to persuade rite industry to adopt new systems. A tool-path generation algorithm that takes advantage of traditional copier systems that do nor fulfil the CNC standards is presented in this paper. The tool path is computed from a "virtually digitised" model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy, and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised for shoe-lass making. Finally, some illustrative examples are given.