Fig. 2024.
In this machine the drill is rocked on the line b, [Fig. 2023], as a centre of motion, this line corresponding to the axis of the shaft of lever f in [Fig. 2019] upon which the chuck swings, and to the line b in [Fig. 2024]. As a result the surface is ground to the form of a cone as denoted by the dotted lines in [Fig. 2024]. The results of the two systems are shown in [Figs. 2025] and [2026], which represent the conical holes made by a drill.
Top View.
Section.
Fig. 2025.
Top View.