Читать книгу The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking - Paul N. Hasluck - Страница 100

The theoretical aspect of this matter has been dealt with already. After the saw is filed, and all the teeth made as uniform as possible in shape, length, and gullet, comes the important operation of setting the teeth so as to afford a ready clearance for the saw-blade. The “set” consists of the setting over, or bending, of each alternate tooth to one side. The set should be as little as circumstances will allow, on account of the amount of labour it entails in working the saw. For dry, hard, thin wood cut lengthways, a very little will suffice; but for soft, wet, thick, or resinous material, a larger amount of set is necessary to free the saw. This is easily understood when it is remembered that the set causes the kerf, or groove made by the teeth, to be slightly greater than the thickness of the plate, so that the broad surfaces of the latter shall move through the wood with the least possible amount of friction. The blades of the best saws are thinned slightly towards the back, but this does not obviate the necessity for setting. Some idea of the set of a hand saw can be obtained from Figs. 289 and 290, p. 75, which, however, somewhat exaggerate the amount of set. No more set should be given to a saw than is absolutely required, as the more the set the greater the power required to work, and the greater the loss of wood. A saw should have only just enough set to clear itself; if it has too much it is not properly guided by the kerf; it wastes too much wood, and does not cut smooth or easy. If the setting is not uniform, power will be wasted. The longest teeth, having the greatest set, are rapidly worn down, and the work turned out, is scored and rough, and at the same time the saw will run from the straight line to the side on which there is most set. if a saw is properly and uniformly set, the teeth should form an angular groove, easily seen when held up to the light and looked at from point to heel.

Fig. 295.—Saw-set with Blunt End.

Fig. 296.—Saw-set with Pointed End.

Fig. 297.—Saw-set with Gauge.