In all of the examples which have so far been given, the work has been done in a horizontal plane, but we shall describe a few cases which are handled in a vertical plane on the vertical turret lathe. As this machine has a turret slide which can be traversed horizontally, it is evident that no special attachments are required for plain recessing or grooving, but there are conditions which may be decidedly out of the ordinary, under which a special arrangement for recessing may be used to advantage, for example, any sort of groove which is deep down in a hole, multiple grooving at a considerable depth, or any other condition of a similar nature. When the groove is very deep, there is naturally a considerable overhang of any tool which may be used for the work. If the overhang is excessive, it follows that there is apt to be more or less vibration, and vibration means chatter. If, however, a tool or bar having an excessive overhang from the turret is supported at its lower end, the tendency to chatter is at once overcome; but, if support is provided at this point, the horizontal movement of the turret slide cannot be used. Therefore, some method which will give a radial movement to the grooving tool must be used when the bar is to be supported at its lower end.

Fig. 8 shows a piece of work at A which is set up so that it can be machined complete in one setting. The casting is held by the inside of the rim in special chuck jaws B, and is supported at three points on the steel buttons C which rest in pockets in the jaws. The inner ribs of the casting act as drivers against the sides of the jaws. The three grooves E are to be machined and the tools G, H, and J are correctly spaced to perform the work. These are secured in the bar D by means of the set-screws K, and accurate adjustment is provided by screws L. The bar D is shouldered at the turret face and is driven by a pin in the turret in the usual manner. The tool 0 in the side head turret is used for facing while the inside work is being done, as this brings the cutting action of the outside and inside tools in opposition and therefore tends to overcome vibration. If very fine feed is used on the turret traverse, good results may be obtained with this method, although there is a tendency to chatter due to the excessive overhang. Slight variations in the depth of the grooves may also be found on account of the spring of the bar.

Fig. 8. A Multiple Recessing Tool used in a Vertical Turret Lathe.