Scrapers. Hand-scrapers are made of saw-plate - material of about the thickness of a panel-saw blade, and having the same degree of hardness. They are usually rectangular, and about 4" X 5", but may be of almost any size and shape. The cutting edge is most easily formed by the production of a surface at right angles to the sides, as indicated by ab, Fig. 107, thus giving two cutting angles, cef and dfe. When a more acute cutting edge is desired, the form shown by Fig. 108 may be adopted; but, as a rule, there is little gained by the keener cutting edge, and double the labor is required to keep it sharp. Scrapers are sharpened by filing or grinding. If smooth work is to be done, the roughness of the edge may be removed on an oilstone, but the rougher edge will cut faster and, generally, will be more satisfactory.

Fig. 109 shows a scraper mounted somewhat like a plane. The scraper blade A, by means of the two nuts B, B, may be changed from a position inclined to the face, as shown, to one perpendicular to the face.

Fig. 107

Fig. 108

Fig. 109

Boring Tools.