A rather peculiar condition is shown in Fig. 4, the work A being an automobile flywheel having a semi-circular recess at B. Attention is called to the fact that this recess is put in at an angle of 45 degrees with the center line. It is evidently only a clearance groove for the male clutch member and it is not known to the writer why some other style of groove would not have answered the purpose just as well.

Fig. 4. A Recessing Tool used in machining an Automobile Flywheel.

The work A is held by the inside of the rim in special jaws. The body of tool D is made of cast steel and is fitted to the dovetailed face of the turret, the gib G securing it firmly by means of the collar-head screws H. A tool-steel pilot E enters the bushing C in the chuck and assists in supporting the body against the pressure of the cut. This pilot E is shouldered and forced into the body at N. A small hole 0 is drilled to avoid air compression when forcing in the pilot. If this is not done the fitter may be deceived into thinking that he has secured a good fit at this point when in reality it is the air compression which causes the stem to fit tightly. A cover plate F tends to strengthen the body and overcome the weakening effect caused by the cutting of the angular slot, and also assists in preventing the entrance of dirt and chips. Tool J is of square section and is held in the sliding block M by two screws L. Hole K is for machining purposes only. The operating screw P is squared up on one end to receive a wrench, while the other end is shouldered at R and threaded to receive a hexagon nut. There are two thrust washers shown at Q. The screw has four Acme threads per inch, right-hand, and meshes with the angular rack cut on the under side of the tool-carrying slide M. It is evident that the rotary motion of screw P will cause movement of the block, in its longitudinal direction, thus feeding the tool into the work at the desired angle. The forged tool 8, held in the tool-holder T on the cut-off slide, is slowly fed across the rim while the recessing operation is taking place.