=45. The upright blow= is delivered so that the hammer strikes the metal in an upright position and fully on the anvil. Such blows force the metal equally in all directions, providing the surrounding dimensions are equal. They will also reduce the thickness of the metal in the direction in which they are delivered, the reduction depending upon the amount of force put into the blows. They are used for drawing where the metal is supposed to spread equally in all directions and for making smooth surfaces.
[Illustration: FIG. 22.—THE UPRIGHT BLOW.]
Figure 22 shows an upright blow as delivered on a piece of flat material. If the material is as wide as the face of the hammer, or wider, the force of the blow will spread the metal equally, but if it is narrower, the blow will lengthen the material more rapidly, because the hammer will cover more in length than in width.
=46. The edge-to-edge blow= is delivered so that the edge or side of the hammer face will be directly above the edge or side of the anvil. When blows are delivered in this manner (_a_, Fig. 23), the hammer forms a depression on the upper side of the metal and the anvil forms one on the bottom.
[Illustration: FIG. 23.—THE EDGE-TO-EDGE BLOW.]
When a piece of metal is to be drawn to a smaller dimension, with shoulders opposite each other, on either two or four sides, these blows will produce the required result to the best advantage. They are more effective if the metal is held at a slight angle across the edge of the anvil face, but then the hammer blows must be delivered a little beyond the anvil edge, so that the upper and lower depressions in the metal will be formed exactly opposite each other, as shown at _b_, where the depressions are indicated by the broken lines.
In forming shoulders such as are required on the hasp exercise (page 64) the first pair may be formed as shown at _b_ and the second pair as shown at _c_. In the latter case the metal is held across the nearer edge of the anvil face and the blows delivered in a manner similar to that described in the preceding paragraph. Hammer blows of this class may be used on any edge of the anvil as required.
=47. The overhanging blow= is delivered so that half the width of the hammer face extends over the edge of the anvil. (See Fig. 24.)