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Once you have got hold of something that looks like a suitable material, you now have to form the boomerang! This is a two stage process..a) Cut the shape / blank / planform, b) File the profile
What Shape?
At first it is best to go for a fairly traditional two bladed affair, maybe like the ones shown above The angle between the two arms is typically 60 to 110 degrees. Boomerangs need to be bent to keep them stable as they spin. Larger boomerangs are heavier to throw and catch but don’t need as much flick of the wrist when thrown and so respond well to new throwers, but don’t necessarily go further. Smaller ones are quicker, cheaper and lighter to make, but take more flick of the wrist to throw. A simple first boomerang might have arms around 10" / 25cm long with a gentle curve at the elbow. A good start is always to copy a boomerang that you like. How do you cut it? Draw your shape on paper first, then trace it onto wood. To actually cut it, an electric jig saw is ideal if you can get hold of one. They are straight forward to use and relatively effortless, but mind the kitchen table. If you don’t have an electric jigsaw, then hand tools can be used. If this is the case, choose a design with straight edges, so a regular (panel) saw can be used as much as possible. For the curved elbow use a coping saw, or It is even possible to drill loads of holes side by side and bodge out the shape like that. Don’t worry too much... the shape isn’t too critical, lots of other factors come into it. Smooth the edges / corners if you need to.
It is the profile / cross section of the arms that really make a boomerang work, a banana shape is not enough! The arms should be shaped into an ‘aerofoil’ shape like a wing.
The picture shows the sort of cross section to aim for on the left, but also the way the layers of ply look when viewed from the top... they act like contours on a map, and guide you, as you file the plywood. Each arm has a leading edge and a trailing edge, these are shown above for a right handed boomerang, but use the mirror image for a left handed boomerang. The arms are often refereed to as the ‘lifting’ and ‘dingle’ arms.. for some reason. To file the shape its best to clamp the blank to a bench or table, but you can hold it under your foot on a chair as you work (I used this method). Start with a coarse file or even rasp / surform, and keep checking the contour lines in the ply. Finish with a finer file, and maybe even a bit of sand paper. Try throwing it before you do too much sanding / finishing. However, by far the easiest wasy is to get a Black and Decker power file. It makes shaping the airfoils incredibly easy and quick.
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