Fig. 784.
Fig. 785.
Mandrels or arbors are sometimes made adjustable for diameter by forcing a split cone upon a coned plug, examples being given in the following figures, which are extracted from Mechanics. In [Fig. 784], a is a cone having the driving head extending on both sides of the centre so as to balance it. Over its coned body fits the shell b, which is split, as shown in [Fig. 785], the splits c, d being at a right angle to splits e, f.
It is obvious that the range of adjustment for such a shell is small, but several diameters of shell may be fitted to one cone, the thickness being increased to augment the diameter. The diameter of the shell should be made to enter the work without driving, the tightening being effected by screwing the nut up to force the shell up the cone.
