After cutting the sides to build a fuselage, a jig can be used to hold the parts straight and squarely while they are glued together. Using a jig speeds up the construction process. Making a jig requires a little time but the final product being straight and square more than offsets the investment of time.
This jig is constructed of a flat piece of 3/4″ MDF. The base should be wide enough to allow some 2″ wide MDF strips along each side of the fuselage. 3/16″ dowels are used for holding the bottom or top firmly to the base.
The base piece should be a little longer than the fuselage and have both ends cut squarely to its sides. Draw a centerline down the length of the base piece. Be sure to get everything square here to achieve professional results later.
The end piece of the fuselage is made of the same width as the base and tall enough to allow it to be attached to the base vertically. Two slots are cut into the end piece to accept the front edges of the fuselage. The table saw blade is set to the thickness of the firewall plus 1/8″. The slots are cut on the table saw spaced to exactly the width of the top and bottom templates. Some fuselages are built with the bottom on the jig base and some are built turned upside down. Choose the side that is flattest.
The end piece is attached to the front of the base with glue and wood screws. MDF will split easily if a screw is inserted without the proper size pilot hole. So be careful and drill and countersink the screw holes.
Insert the two fuselage sides into the front slots. Lay in the top (or bottom) template onto the base between the two sides.
Cut two strips of 3/4″ MDF to 2″ wide about 2″ or 3″ longer than the length of the fuselage before it begins to taper. These are then placed firmly but squarely against the sides of the fuselage to press them against the part laying in between them. They are then glued or pegged into place. My jig uses the same 3/16″ dowels used for the fuselage jig to hold the MDF strips in place. If you use pegs it is important that the pegs are tight in the drilled holes. It is also very important to make sure the fuselage sides are kept square to the front of the jig before gluing or pegging the MDF strips to the base. Use the centerline to assist in keeping everything square.
The top (or bottom) fuselage must be held securely onto the base while gluing. Since there are already peg holes in the part, the existing peg holes are drilled into the MDF. Lay the top (or bottom) template onto the base and use the existing peg holes as a drilling guide. Be careful to properly align the template. Do not allow the part to move while drilling by inserting a peg into each hole as they are drilled. Check that the template stays properly aligned on the centerline as each hole is drilled.
Test fit the parts on the jig. Make any adjustments before any gluing begins. The parchment paper was test fitted here too. It will protect the jig from glue run out. It did not affect fitment.
The next step is to make some former templates. See the former templates posting.
Fuselage Jig Use:
With all the formers cut, the fuselage buildinging can begin. The jig will be used to hold everything in place. CA glue will be used to tack everything together. Use of too much glue can glue the fuselage to the jig if the glue runs out. Parchment paper can help you avoid that.
First install the top or bottom onto the jig base securing it with dowels. The one in this example is built with the top side down. The top side is attached to the jig.
Next the fuselage doublers are glued onto the sides. Again pegs are used to align the two parts while gluing. The doubler should leave room for the front of the fuselage sides to fit into the grooves on the jig. Also the doubler should rest on the edges of the top side while the fuselage sides fit beside the top side edges. This keys the top onto the fuselage.
Install the two sides with the doublers already attached into the front end slots. Be sure they are fully in the slots and that they are resting on the MDF base.
Now the formers can be glued in their proper locations. Use a square to keep them vertical while the glue sets. At the place the fuselage sides begin to taper, use some wedges to force the bends to be tight bends.
Tack glue strategic locations to keep everything together.
CA will be dripped into the corners of each piece later to finish the gluing. The firewall is glued in later with epoxy and aluminum angle supports.