Fig. 960.
Fig. 961.
When the tool is very narrow at c, [Fig. 960], or long as in [Fig. 961], it may be strengthened by being deepened, the bottom b projecting below the level of the tool steel, which will prevent undue spring and the chattering to which this tool is liable.
To enable the sides of the tool to clear the groove it cuts, the width at c should slightly exceed that at d, and the thickness along the top a should slightly exceed that at the bottom b.
When the tool is used to cut a wide groove as, say, 3⁄8-inch wide, in a small lathe, it is necessary to carry down two cuts, making the tool about 1⁄4 inch wide at c, which is a convenient size, affording sufficient strength for ordinary uses.
