Fig. 837.
[Fig. 837] represents a similar chuck for all sizes between 4 and 15 inches, the designated sizes of the chuck being 6, 9, and 12 inches, these diameters being the largest the chucks will take in.
Fig. 838.
[Fig. 838] represents a Horton chuck with outside bites for opening out to grip the bores of rings or other hollow work.
The term scroll chuck is applied to universal chucks in which the jaws are operated throughout their full range by means of a scroll thread such as was shown in [Fig. 817]. The objection to this form is that the threads on the jaws cannot be made to have a full bearing in the scroll thread.
