Fig. 1627.
[Fig. 1627] represents a centre chuck to enable the cutting of spirals. The principle of the design is to rotate the work as it traverses, and this is accomplished as follows:—
Upon the bed of the machine alongside of the table is bolted the rack a a, into which gears the pinion b, which is fixed to the same shaft as the bevel-gear c, which meshes with the bevel-wheel d. Upon the same shaft as d is the face plate e, and in the spindle upon which d and e are fixed is a centre, so that the plate e answers to the face plate of a lathe. f is a bearing for the shaft carrying b and c, and g is a bearing carrying the spindle to which e and d are fixed. h is a standard carrying the screw and centre, shown at i, and hence answers to the tailstock of a lathe. k represents a frame or plate carrying the bearings f and g, and the standard h. l represents the table of the planing machine to which k is bolted. The reciprocating motion of the table l causes the pinion b to revolve upon the rack a a. The pinion b revolves c, which imparts its motion to d, and the work w being placed between the centres as shown, is revolved in unison with e, revolving in one direction when the table k is going one way, and in the other when the motion of the table is reversed; hence a tool in the tool post will cut a spiral groove in the work.
To enable the device to cut grooves of different spirals or twist, all that is necessary is to provide different sizes of wheels to take the places of c and d, so that the revolutions of e, and hence of the work w, may be increased or diminished with relation to the revolutions of b; or, what is the same thing, to a given amount of table movement, or a stud may be put in so as to enable the employment of change gears.
Fig. 1628.
[Figs. 1628] and [1629] represent a universal planer chuck, designed and patented by John H. Greenwood, of Columbus, Ohio, for planing concave or convex surfaces, as well as ordinary plane ones, with the cross feed of the common planer.