Fig. 1276.
Fig. 1277.
As the knurling tool requires to be forced against the work with considerable pressure, there is induced a strain tending to force the tool directly away from the work, as denoted by the arrow in [Fig. 1276], and this, in a weighted lathe, acts to raise the lathe carriage and weight. This is avoided by setting the tool at an angle, as in [Fig. 1277], so that the direction of strain is below and not above the pivot on which the cross slide rests. This is accomplished by pivoting the piece carrying the wheels to the main body of the stem, as shown in [Fig. 1277].
Fig. 1278.
For use by hand the knurling or milling tool is fitted to a holder and handle, as in [Fig. 1278], and the hand tool rest is placed some little distance from the work so that the knurl can pass over it, and below the centre of the work.
Knurls for screw heads are made convex, concave, or parallel, to fit the heads of the screws, and may be indented with various patterns.