Dahlegren lathe with countershaft, cutters and specimens of work and accessories

This special lathe, patented in 1891 by Messrs Dahlgren & Svensson of Sweden, is for turning such sections as squares and hexagons. This it accomplishes by revolving the work between centres in the manner usual in turning, while using as a cutting tool a revolving cutter with several cutting points arranged in a circle and uniformly rotated.

The speed of the cutters depends upon the number of facets to be produced, and upon the diameter of the cutting path, and they revolve in the same direction as the work. Although the facets produced are not true planes the deviation can be reduced to an amount that is scarcely perceptible with a straight-edge. The action of the lathe is made clear by a model.

As set up for cutting hexagons, the revolving tool consists of three cutters, carried on a spindle at the back. The work, which revolves at half the speed of the cutters, is carried between centres mounted on a saddle by which the distances between the work and cutter axes can be altered. Both headstock spindles are connected by gearing to a lower belt-driven shaft, swinging arms being introduced to carry change-wheels, and give a flexible connection. The headstock holding the work is moved longitudinally by a screw thus automatically feeding the work along. It also has an arrangement by which the correct setting of the work in relation to the path of the cutters can be effected.