Bore a hole centrally through the assemblage, and place therein a pin B. The contact faces of these strips should be previously well painted over with hot glue liberally applied. When they are then placed in position and the pin is in place, the ends of the separate pieces are offset, one beyond the other, a half inch, as shown, for instance, in Fig. 79.
This will provide ends which are eight and a half inches broad, and thus furnish sufficient material for the blades. The mass is then subjected to heavy pressure, and allowed to dry before the blades are pared down.
Fig. 79. Arranging the Strips.
MAKING WIDE BLADES.—If a wider blade is desired, a greater number of steps may be made by adding the requisite number of strips; or, the strips may be made thicker. In many propellers, not to exceed four different strips are thus glued together. The number is optional with the maker.
An end view of such an assemblage of strips is illustrated in Fig. 80. The next step is to lay off the pitch, the method of obtaining which has been explained.
Fig. 80. End view of Blank.
Before starting work the sides, as well as the ends, should be marked, and care observed to place a distinctive mark on the front side of the propeller.
Around the pin B, Fig. 81, make S-shaped marks C, to indicate where the cuts on the faces of the blades are to begin. Then on the ends of the block; scribe the pitch angle, which is indicated by the diagonal line D, Fig. 80.
Fig. 81. Marking the Side.
This line is on the rear side of the propeller, and is perfectly straight. Along the front of this line is a bowline E, which indicates the front surface of the propeller blade.