Screw arbor chucks are used for works already partially completed such as discs and wheels, which may be fixed in this manner whilst their edges are turned or cut into teeth; in such cases the stability of the arbor chuck may be sometimes advisedly increased by the support of the popit head. Many similar contrivances are made to run between centers, or in the square hole chuck, these are usually for some definite purpose, such as the spindles for saws, circular cutters and similar tools.
Surface chucks for fixing works in contact with their faces vary in material and dimensions, but all present a plain flat surface, to which the work is fixed by different methods ; they are used both for wood and metal turning, and are essential to a large proportion of the latter works. The Cement chuck used for wood and ivory, is usually a plain boxwood chuck from about one to four inches in diameter; the face of this is turned to a surface, and subsequently, for the better adhesion of the cement, the surface is slightly roughened or else scratched full of rings, turned upon it with a point tool or an outside screw tool. A stick of turner's cement, prepared as described, page 160, Vol. I., is pressed hard against the chuck while in rapid revolution, until a uniform coating of about one sixteenth of an inch thick, is melted upon it by the friction. The work held in the fingers is then in turn pressed against the chuck, still in rapid revolution, the friction from which again softens and renders the cement adhesive; with the friction still continued, the speed of the lathe is next very considerably reduced, to enable the position of the work to be quickly examined, both edgewise and for centrality. If untrue in either direction the work is at once adjusted before the cement cools, and in a minute or so after the hand is withdrawn or the lathe brought to rest, the cement becomes entirely set and holds the work sufficiently fast for turning. The adjustment for center may be obtained more exactly when required, by means of a fine wire placed in the center of the chuck, entering a hole made in the axis of the work, it is then only necessary to examine the truth of the work edgewise. The turner's cement effectually sustains the ordinary resistance to the turning tool, but it cannot withstand a sudden blow or jerk, a little care not to take too heavy a cut therefore is alone necessary; the work is readily removed by a slight blow on its side, or by the edge of a tool thrust between it and the chuck.
Work in both wood and ivory, is constantly fixed upon the Wood surface chuck by ordinary joiner's glue, and this method is in every respect preferable, except that it requires time, not being instantly available like the cement; but when several pieces are required, they may be generally mounted upon as many chucks at one gluing. The contact between the two is intimate and consequently truer, the position can be more deliberately adjusted, and the hold is so secure that the work is often with difficulty removed from the chuck. Their separation is assisted by a piece of thin paper placed between the two surfaces when glued together; the insertion of a thin tool or the blade of a knife then splits the paper and detaches the work without risk of accident.
Gluing the work upon the wooden surface chuck, is constantly resorted to for slabs of wood and ivory, both in plain and ornamental turning; for the latter, in which flat pieces are frequently pierced or cut into various figured outlines by revolving drills or cutters, this practice is adopted both for the solid support obtained, and also that the point of the tool may cut through the work into the surface of the wood chuck, without itself receiving damage or splintering the under surface of the work. The piece of paper is sometimes interposed, but it is not usually employed with the more delicate of these works in ivory, which are detached by standing the work and chuck in a shallow vessel of cold water until the glue dissolves.
Wood, ivory and some light metal works, are also fixed to the wood surface chucks by ordinary joiner's screws, passing through holes made in portions of the work that will be subsequently hidden or removed; if the work have permanent apertures the screws may be passed through them, small metal washers of different widths being placed beneath their heads to bear upon the work. When the entire surface of the work has to be turned, the screws may sometimes be placed in from behind the chuck and allowed only to partially penetrate the work. In addition, all the various methods of fixing metal work, central or eccentric, described for the metal surface chuck, may be copied for wood turning upon the wooden surface chuck; only, the apparatus required is less strong, and is otherwise modified by the difference of material in both chuck and work. Instances of the further employment of the wood surface chuck, for the production of eccentric and other turned forms used for ornament, will also be found among the examples of combined plain turning.
Thin metal works are frequently cemented upon metal surface chucks. The cement used is made of a mixture of rosin and beeswax, usually without other ingredients and in the proportion by weight, of three of the former to one of the latter, melted together. The chuck having being first warmed, a thin layer of the cement is poured on the face and spread level, the work is then adjusted in position, and both it and the chuck equally heated to remelt the cement. Plates and pieces of metal of less size than the surface chuck, may often be sufficiently firmly cemented to it and with more accuracy, by applying the surface of the work directly to that of the chuck, and then pouring the hot cement in the angle around the margin of the work; or, the cement may be melted into the angle by a tinman's soldering iron. Metal works of moderate size that are thicker, or require a more secure hold than that afforded by cement, are generally attached to the metal surface chuck by soft solder, introduced between the two cleaned surfaces. The whole has then to be heated to the melting point of the solder.