Fig. 945.
Fig. 946.
In [Fig. 945] the point of the tool is made considerably lower than the point b, and as a result the cutting would rise somewhat vertically as in [Fig. 946]. Indeed the heel b may be raised so as to cause the cutting to move but little to the right, but rise up almost vertically, being thrown over towards the work, and in extreme cases the cutting will rub against the surface of the work and the friction will prevent the cutting from moving to the right, hence it will roll up forming a ball, the direction of the rotation occasionally changing.
Whatever irregularities may appear in the coil of the cuttings will, if the tool is not dulled from use, arise from irregularities in the work and not from any cause attributable to the tool.
The strength of a cutting forms to a great extent a guide as to the quality of the tool, since the stronger the cutting the less it has become disintegrated, and therefore less power has been expended in removing it from the work.
The cutting speed for wrought iron should be sufficiently great that water being allowed to fall upon the work in a quick succession of drops as, say, three per second, the cuttings will leave the work so hot as to be almost unbearable in the hands, if the cut is a heavy one, as, say, reducing the work diameter 1⁄2 inch at a cut.