Cut the can down to the line A, then take up a small sharp-cornered file and file completely through the rolled rim at the corners marked C and C on the line B. Use the edge of the file and make a triangular cut. This filing will greatly simplify cutting the rolled rim which is hard to cut through with the shears.
Then cut into the rim on the line B, cutting from the line A. Bend the two halves of the can open far enough to admit the shears and cut across the bottom of the can on the dotted line B. Cut very carefully so that the part of the can at the line B, forming the bottom of the hood, will rest flat on the bench all around. If it rests flat on the bench, it will rest flat on the tin frame of the truck where it is to be soldered in place.
The next thing to do is to punch the holes to form the radiator. The front of the hood is rested on a block of wood and a very sharp punch should be used for punching the holes, such as an ice pick or a very sharp-pointed nail.
First mark off the radiator in regular squares, using the depressed line usually found in the bottom of this type of can as a boundary line for the squares. Divide up the space into squares as indicated in Fig. 60, A, leaving a clear border of tin all around the space to be punched.
Find a block of wood that will fit inside the hood as shown in [Fig. 60], C, and place one end of this in the vise. See that the end is sawn off square before placing the hood over it in the position shown.
Take up the punch and carefully punch the holes as they are marked by the dots in [Fig. 60], A, at each line intersection. Then punch a hole in the center of each square and then a hole should be punched between every other hole on all the lines forming the squares, see [Fig. 60], B.
Care should be taken to punch all the holes of the same size and to get them in regular rows. This makes a neat and workman-like job.
Cutting the Vents.—Vents may be cut in each side of the hood with a sharp chisel. An old wood or carpenter’s chisel about an inch wide will do very well or a sharp cold chisel may be used.