In sharpening the pivots of a drum clock balance, hold the axis of the balance by one end in a pin-vice and sharpen the centre of the other end on an oilstone, at the same time revolving the pin-vice rapidly in the fingers with a twirling motion. This will keep them circular and prevent flats being formed. Watch and clock drills are also held in a pin-vice for sharpening and carefully rubbed on the oilstone. An inspection of a new drill will show the correct shape and angle for the cutting edges.