The manipulation of the hand turning tools for metal, in many particulars greatly resembles that of the tools employed both upon hard and softwood, while the analogies between the cutting action of the wood and metal tools, are generally close and apparent. The correct management of the turning tool however, can be far more readily appreciated in wood than in metal turning, on account of the more decided and visible cutting action exhibited in the removal of the wood shaving, and also, from the more tangible, successful or faulty results obtained upon the work. Whence it is found that success in hand turning in metal is more easily acquired, if preceded by a moderate proficiency or even some little practice in turning wood.i

Some of the analogies between the metal and wood turning tools, have been pointed out in the second volume, and with some others, will be recognized in the following pages and in practice; although they may be to some extent obscured, by the different modes of holding the tools and the different cutting angles, necessary from the increased hardness of the material. The latter circumstance also very greatly reduces the quantity removed by the tool at each individual cut; but on the other hand in metal turning, less of the material usually requires reduction. Unless the finished work nearly approaches the cylindrical form, it is seldom produced direct from the cylinder by the removal of the superfluous portions, so convenient a mode in wood turning. A near approach to the form is usually first given, either by forging or casting, and the use of the turning tool is thus limited to reducing the different superficies to their required dimensions and concentric truth. The slide rest with a fixed tool is very generally employed for turning metal, and by its rapidity and truth of execution, largely supersedes the more painstaking use of the hand tool. The lathe may however be unprovided with this valuable adjunct, while for many works its use may be neither convenient nor necessary, so that a large quantity of metal work remains that requires execution by the hand turning tool alone.

The more general of the forms turned in metal are principally composed of the external cylinder and surface; very frequently, several different dimensions of both superficies, together with others, being combined more than once in the same solid. Cones and curves are less frequent; the first being usually working fittings, and centers of motion ; curves, being very generally employed merely to connect the cylinder to the surface, to break an external or internal corner and for ornament. The internal forms are the corresponding apertures, the smaller, produced by boring or drilling, the larger being generally first cast or forged in the material; both are enlarged or finished to size with the turning tool, and sometimes by grinding or other means as required. The above mentioned plain forms, and a few familiar examples of their combination, are proposed as illustrations for the manipulation of the hand turning tools for metal. The different methods of chucking these various forms will be found in a preceding chapter.