Document Qk2eDX9xm2R3ydj6NzzyDea8E

HAND AND PORTABLE POWER TOOLS hardened and tempered, only an emery wheel, grindstone, file, or oilstone need be used to keep the head in shape and the edges clean and sharp. Never gnnd hardened tools until after they have been drawn or tempered Gnnd in easy stages with no attempt to take off much metal at one tune While grinding, keep the tool as cool as possible with water or other cooling medium. Shock tools that require a soft or medi um-soft edge should be dressed as soon as they begin to mushroom (Fig 30-4) A slight radius ground on the edge of the head when it is dressed will enable the tool to stand up better under pounding and will reduce the danger of chips being knocked off. Tests have shown that a radius of 16 to %e in. is satisfactory on ordinary hand tools. A file, rather than an abrasive wheel, is recommended for re-forming screw driver tips and for sharpening pike poles and axes With a file, there is less danger of drawing the temper. A wood-cutting tool, because of its feath er cutting edge, should be shaped on a wet grindstone with plenty of water, or on a grinder having a wheel recommended by the manufacturer for that type of tooL To prevent overheating or burning, the tool should not be pressed too bard against the gnnder Frequent dipping m water will help to keep it cooL To shape wood chisels, an oilstone set securely m a wood block placed on a bench can be used The oilstone should never be held m the hand because a slip off the face of the stone could cause a severe hand in jury After a wood-cutting tool has been shaped, it should be whetted on a clean oil stone to produce a sharp cutting edge (Fig 30-5) Often a few finishing strokes on a leather strop will produce a keener edge Meta] cutting tools and hammer-struck surfaces, because they have greater body, can be dressed and sharpened on an emery wheel Care should be taken that the tool does not overheat from too much pressure against the gnnder The manufacturer's recommendations for type and kind of grind ing wheel should be Mowed, Each cutting edge should have the correct angle accord ing to its use and be finished off with a file. Fig. 30-5. This figure shows the correct way to whet a wood chisel or a plane Iron on an oilstone to produce a sharp cutting edge. The bevel should be placed on the stone with the back edge slightly raised. Handles The bandies of band tools should be of the best straight-grained material, prefer ably hickory, ash, or maple, and should be free from divers To make sure that they are properly attached, bandies should be fitted to tools only by an experienced per son Poorly fitted handles make it difficult for the worker to control the tool Loose handles in sledges, axes, hammers, cold cutters, and similar tools create a haz ard No matter how tightly a handle may be wedged at the factory, both use and shrinkage will loosen it In some cases, tapping the wedge will take up the shrink age. La others, the head of the tool can be driven bade on the handle and the protrud ing end of the handle cut off Eventually, any tool will have to be re wedged The wedge is picked out and the handle is driven off If the wood of the handle does not bear against the bead eye at all points, shave the handle until it fits snugly Then replace the handle in the tool and sight along it to be sure that the head is properly centered. After the handle is properly fitted into the head eye, replace the wedge. 30-6