American Scroll Chuck
This chuck is made upon the same principle as the Warwick Drill Chuck—namely, a flat spiral so acting on three jaws sliding in radial grooves as to make them recede from the centre to admit any object between certain sizes, and then to be tightened upon it. Fig. 1 is a plan of a 4-inch chuck. Fig. 2 is a vertical section of the same. Fig. 3 is a view of the outside of the chuck, and Fig. 4 is a separate section of the principal part a, a, taken through the line z, z (Fig. 1).
In Fig. 2, a, a is this piece, b, b, has the spiral cut on it which actuates the jaws 1, 2, 3 (Fig. 1), c, c screws on the piece a, a to keep b, b in its place and d, d is the plate which screws on the mandrel, and which is fixed to c, c, by three countersunk screws, one of which is shown in section.
If the foregoing observations are carefully studied the further practice of plain hand-turning in wood will not be difficult, and we shall proceed to speak of metal turning, before passing to a description of the Slide Rest and other apparatus usually added to the lathe. We may, however, observe here, that, for ivory and hard wood—especially the former, the first roughing down cannot be done with the gouge. A point or small round-ended tool must in these cases take its place, to be succeeded by one or more of those tools which rather scrape than cut, as described in detailing the process of hollowing out boxes and similar work.