Fig. 8. Tool used for Cylindrical Turning
Turning Tool—Turning Work Cylindrical.—The tool used to turn the body to the required diameter is shaped differently from the side-tool, the cutting edge E of most tools used for plain cylindrical turning being curved as shown in [Fig. 8]. A tool of this shape can be used for a variety of cylindrical turning operations. As most of the work is done by that part of the edge marked by arrow a, the top of the tool is ground to slope back from this part to give it keenness. The end F, or the flank, is also ground to an angle to provide clearance for the cutting edge. If the tool did not have this clearance, the flank would rub against the work and prevent the cutting edge from entering the metal. This type of tool is placed about square with the work, for turning, and with the cutting end a little above the center.
Fig. 9. Setting Calipers by Scale—Setting by Gage—Fixed Gage
Before beginning to turn, a pair of outside calipers or a micrometer should be set to 21/4 inches, which, in this case, is the finished diameter of the work. Calipers are sometimes set by using a graduated scale as at A, [Fig. 9], or they can be adjusted to fit a standard cylindrical gage of the required size as at B. Very often fixed caliper gages C are used instead of the adjustable spring calipers. These fixed gages, sometimes called “snap” gages, are accurately made to different sizes, and they are particularly useful when a number of pieces have to be turned to exactly the same size.
Fig. 10. Views showing how the Cross-slide and Carriage are Manipulated
by Hand when Starting a Cut—
View to Left, Feeding Tool Laterally;
View to Right, Feeding Tool in a Lengthwise Direction