Fig. 1965.
Fig. 1966.
To cut V-shaped grooves in cylindrical work, when it is required that one face or side of the groove shall be a radial line from the centre of the work, two methods may be employed. First we may form the cutter, as in [Fig. 1965], the side b of the cutter being straight and the point of the cutter being set over the centre of the work. The objection to this is that the finished groove will have a projection or burr on the radial side of the groove, as shown at d in the figure, entailing the extra labor of filing or grinding, to remove it; furthermore, that face will have fine scored marks upon it, as denoted by the arcs at c, these scores showing very plainly if the cutter has any high teeth upon it, and more especially in the case of cutting spirals, as will appear presently. The reason of this is that the side b of the cutter being straight or flat the whole of the teeth that are within the groove have contact with the side c of the groove, that is to say, all the teeth included in the angle e in the figure, because the teeth on the side a tend, from the pressure of the cut to force the cutter over towards the side c of the groove. The second method referred to, which is that commonly adopted for cutting the flutes of tapes, reamers, milling cutters, &c., is to form the cutter on the general principle illustrated in [Fig. 1966], and set it to one side of the centre of the work so that one of its faces forms a radial line, as shown in the figure, the distance to which it is set to one side depending upon the angle of its cutting edge to the face of the cutter.
Fig. 1967.