Fig. 1952.
[Fig. 1952], which is from an article by John J. Grant, represents a gang of cutters arranged to mill out the jaws and the top faces of a head for a lathe; and it is obvious that a number of such heads may be set in line and all milled exactly alike.
The Number of Teeth in Mills or Cutters.—The teeth of cutters must obviously be spaced wide enough apart to admit of the emery wheel grinding one tooth without touching the next one, and the front faces of the teeth are always made in the plane of a line radiating from the axis of the cutter.
In cutters up to 3 inches in diameter, it is good practice to provide 8 teeth per inch of diameter, while in cutters above that diameter the spacing may be coarser, as follows:—
| Diameter | of cutter | 6 | inches, | number of | teeth in cutter | 40 |
| „ | „ | 7 | „ | „ | „ | 45 |
| „ | „ | 8 | „ | „ | „ | 50 |
Fig. 1953.