The surface may be turned at either end of a cylinder, when held between centers. That next the popit head is first finished, almost, but not quite, to the center; leaving a small central projection for the support of the point, which is treated as in turning a cone, standing the same way as the point of the popit head. The two are then carried on simultaneously, the surface being finished to the center and the little cone to its apex, which separates them one from the other. The point of the popit head is then advanced to make a fresh center in the finished surface, to afford support to the work while turning the surface at the chuck end. A small portion of the wood against the prong chuck is sacrificed, turned to a cone in the same manner and separated from the back surface, at the moment the latter is completed to its center, when the work falls free from the chuck. This method is constantly followed, either for surfaces or other forms, and presents no difficulty, except that the work may become disengaged from the cone which carries it at either end, before the surface is sufficiently finished.
When the work is mounted in a plain driving chuck, figs. 346, and 349, undivided attention can be devoted to the management of the tools, the work is secure, with or without the support of the popit head, and in the latter case, the front surface neither requires the supporting cone, nor shows the center mark left by the point of the popit head. The surface at the chuck end of the cylinder is turned with still greater ease and convenience, when the work permits of being reversed and re-chucked, in a plain wood chuck or in a spring chuck, when it occupies the previous position of the front surface.
The back surface when turned as such, is commenced by a division in the material fig. 346, which may be made by a series of cuts with the gouge, held on its side and turned over between every cut, as shown by the dotted lines. The surface end of the gap is made nearly perpendicular, the bevil of the tool being directed in agreement with that plane; the gouge is followed by the chisel, to finish the surface, and separate it from the portion next the chuck. The division may be made entirely with the chisel, fig. 349, when thus made, it is narrower and wastes less wood, the tool does not require turning over, but only that its angular direction be changed, when withdrawn from the work between every cut. In other respects the tools are held and managed as upon the front surface, except that the work being now left-handed, the angular positions are reversed.
The back surface is finished with the chisel down to the bottom of the division, until found correct or flat as tested by the straight-edge, when it serves as a guide for the chisel while turning away the neck, to finish its center. The cutting bevil of the chisel, is then made to traverse the completed portion of the back surface without cutting, that is, in exact agreement, until the lower angle reaches the neck, into which it is made to enter a short distance, by pressure, with the coincidence of the bevil and the finished surface undisturbed. The edge of the chisel therefore, without touching the finished portion of the surface, takes it up exactly at its termination and prolongs it towards the axis, the depth it has entered the neck. The tool is withdrawn from this surface cut and presented again, just clear of the surface, the under side of its lower angle exactly radial, with the top edge of the blade a little inclined towards the chuck. In this second position the tool acts upon the neck alone, reducing the part touched by the tool to a cone, to the depth of the preceding surface cut. The chisel is next returned to the surface, which it prolongs a little further towards the center, followed by a second cut upon the cone, and a succession of these alternate cuts carefully taken, finishes the surface to the center and at the same time separates it from the piece in the chuck. When the work is of moderate size, the left hand is usually removed from the tool at the last cut and placed around the work, to catch it as it falls from the chuck.
When the cylinder is in excess of its required length, the softwood parting tool, figs. 333. 334, may be used to divide it from the piece remaining in the chuck. The parting tool is mounted in either a long or short handle according to its size, and is presented to the work the blade resting exactly vertically upon its edge, the grooved side beneath, with the apex directed radially. The two sharp points at the angle, formed by the grooved side with the plain ground bevil, divide the fibres, cutting square across them like the point of a knife; the material removed is ploughed out by the angular groove between the points, which1 when keen leave the sides of the work fairly smooth.
As the parting tool approaches the center of the work, it is slightly retarded, greater care being taken to prevent the tool deviating from and falling below the radial line; should it do so, the tool pushes forward and becomes wedged beneath the small neck formed in cutting off the work, to the probable damage of its delicate points. When so misplaced it cannot regain its radial position by being forced upwards, for the rest acting as a fulcrum, the points would be forced into the neck and broken; to free the tool, the point is still further lowered, the tool withdrawn from the work without stopping the lathe, and the cut recommenced.