A thin piece of work for electrical machinery, shown at A in fig. 11, has been completely machined with the exception of the groove B. At the time when the operation of grooving takes place, a revolving steel pilot G fits the previously reamed hole C and is held in its position on H by the nut and washer J and K. The upper portion of the bar F is shouldered at E and fits the turret hole, being kept from turning by pin D. A round bar N is flatted on two sides at O and is held in the side-head turret by the three screws R. The lower portion of the bar carries the grooving tool P which is held in place by the two screws Q. A tool-steel pin M is forced into the bar N and forms a sliding tie between the pilot bar F and the side-head bar N. The bushing L is inserted in the pilot bar to receive the pin. It will be readily seen that this method overcomes the vibration which would naturally be caused by the grooving tool acting on the thin and unsupported hub.

Fig. 11. An Arrangement for cutting a Groove on the Outside of a Sleeve.