Fig. 252. [↑]
Fig. 253. [↑]
Fig. 254. [↑]
The principal objection to the metal propeller is the bending that is liable to occur when the model lights, unless there are lighting devices underneath, and they all add weight. The hub propellers may have metal or hardwood veneers for fans. The hub may be round or square; see Figs. [252] and [253]. Very good propellers may be made in this way. Extra curvature of the outer ends of the fans is possible, [Fig. 254].
The veneer propeller must be steamed and pressed. This is by far the most difficult to make. The 1/16” hardwood veneer is the best. The propeller is not reinforced to make up for the extra thickness of the carved propeller, but is of uniform thickness thruout. The veneer is first cut to shape in outline and then is steamed and twisted to shape. [Fig. 255] shows a pattern for a propeller blade. The veneer should be steamed or soaked in hot water until the wood is very pliable and soft. A form should be ready so as to get both wings with equal twist from the central portion. I will suggest one, others can be devised. A clamp is necessary for the center, which may be made as follows: take a one-inch piece of wood about 1¼” wide and any length. Set it up edgewise. Make a cut 1/16” deep and one inch long across the upper edge, [Fig. 256], and screw a small piece over top as a clamp. After thoroly steaming the propeller blade until it is very pliable, insert it into the clamp at the center and twist from the straight side, one fan up, the other down. It is not easy to get the two sides just alike, so I recommend the bending of one side at a time, and when that is dry, remove, and reverse the ends, being sure to keep the straight edge to the front, or the same as before. To be accurate, there must be a guide block to bend to. For a nine-inch propeller, a block like [Fig. 257] would be about right. Place guide in position, press blank down to the oblique surface and secure there until dry. Repeat for the other end. It will be seen that the guide block and clamp are both secured to a board for a base; they may be secured to a table or bench-top. A clamp might be devised also that would hold the propeller in a vertical position with guide blocks on either side of center so as to bend and secure both ends at the same time.