Jigsaw with saw blade - has blade driven by belt round pulleys, with cam and belt tensioner

摘要

The jigsaw consists of a housing in two halves containing four pulleys, three of which (B,C,D) are idle, while the fourth is a driving one, oscillated by a cam and connecting rod. The saw blade (L) is attached by fixings (G) to the ends of a belt (S) which passes round the pulleys and is kept under tension by an additional tensioning pulley (PT) inside the housing. - As the driving pulley oscillates, the saw blade moves up and down between the jaws of the jig. In variants the driving pulley can be made of different dimensions, with the cam located in an aperture in the pulley or outside the housing.