The Proper Bevel—Position of Tools on Oilstone—Good and Bad Edge—Stropping—Paste and Leather—Careless Sharpening—Rubbing Out the Inside—Stropping Fine Tools—Importance of Sharp Tools.
Having given this brief description of the tools and materials used by carvers, we shall suppose a piece of work is about to be started. The first thing the carver will require to do is to sharpen his tools. That is, if we may assume that they have just come from the manufacturer, ground but not yet brought to an edge. It will be seen that each has a long bevel ending in a blunt ridge where the cutting edge should be. We shall take the chisel No. 10 and sharpen that first, as it is the easiest to do, and so get a little practise before we try the gouges. The oilstone and oil have already been described. The first thing is to well oil the stone and lay it on the bench in a position with its end toward the operator.
A. ANGLE FOR SOFTWOOD B. ANGLE FOR HARDWOOD Fig. 8.
Tools which are going to be used in soft wood require rather a longer bevel and more acute edge than when they are wanted for hard wood. Both angles are shown in Fig. 8. Lay the flat of the tool on the stone at an angle of about 15°, with the handle in the hollow of the right hand, and two fingers of the left pressed upon the blade as near to the stone as possible. Then begin rubbing the tool from end to end of the stone, taking care not to rock the right hand up and down, but to keep it as level as possible throughout the stroke, bearing heavily on the blade with the left hand, to keep it well in contact with the stone. Rocking produces a rounded edge which is fatal to keenness. C (Fig. 9) gives approximately, to an enlarged scale, the sections of a good edge, and D that of an imperfect one.
C. GOOD CUTTING EDGE D. BADLY FORMED EDGE. Fig. 9.
Practise alone will familiarize the muscles of the wrist with the proper motion, but it is important to acquire this in order to form the correct habit early. It should be practised very slowly at first, until the hands get accustomed to the movements. When one side of the tool has been rubbed bright as far as the cutting edge, turn it over and treat the other in the same way. Carvers' tools, unlike joiners', are rubbed on both sides, in the proportion of about two-thirds outside to one-third inside. When a keen edge has been formed, which can easily be tested by gently applying the finger, it should be stropped on a piece of stout leather. It will be found, if the finger is passed down the tool and over its edge, that the stoning has turned up a burr. This must be removed by stropping on both sides alternately. A paste composed of emery and crocus powders mixed with grease is used to smear the leather before stropping; this can either be procured at the tool shop, or made by the carver. When the tool has been sufficiently stropped, and all burr removed, it is ready for use, but it is as well to try it on a piece of wood first, and test it for burr, and if necessary strop it again.