Accurate Returning Boomerang From Plywood

Boomerangs are lots of fun to throw and to make. They are truly magical when they come back to you after a big, circular flight. Almost as if they remember where you are standing. But be warned: once you've made a returning boomerang, you can never get rid of it! If you throw it away, it always come back.

This is certainly not the first instructable about making boomerangs, but I've been making boomerangs for a while now, and wanted to share my experience with everyone. If you're thinking to make one to add to your weapons arsenal, I'll have to disappoint you. The real hunting boomerangs used by ancient tribes were of the non-returning kind and quite heavy. The returning ones were most likely for entertainment, and possibly to scare birds into nets (although written sources are non-existent). The boomerang we're making weighs only 80g (less than 3 ounces), so I doubt you'd be killing anything larger than a fly.

Let's get started!

Step 1: Get the Materials You Need

No boomerang without wood, so find a sheet of plywood first. I'm using a 5 mm (13/64 inch) special plywood called aircraft birch plywood. It has 2 layers per mm (10 in total), which makes it super strong but super expensive. It's the best there is for boomerangs, but don't worry if you can't find it. A good quality plywood from lumber stores should do nicely too. I recommend searching for a 6 mm (1/4 inch) plywood, with 3 to 5 layers. The more layers, the better. Also mind the quality, indicated by a letter. A or B are good, but BB and C are not because they can contain large knots and filled up voids. Those weak spots will make your boomerang break easily.

You will also need:

- an electrical jigsaw or scroll saw (or if you're up to the task: a coping saw)

- a wood rasp or a metal file (or both)

- sandpaper in 3 grits (coarse, medium and fine)

- 2 clamps

- acrylic paint

- wood varnish

- a boomerang template like this one:

Step 2: Cut Out Your Boomerang

Trace your template onto your wood, clamp the wood down and start cutting! If you're left-handed, flip the pattern upside down (later, you'll see why). If your plywood is chipping too much, use a blade with smaller teeth. Go slow, and let the blade do the cutting for you. Once you're done, take your coarse sandpaper and sand the edges to get rid of any imperfections.

Step 3: Add Wing Profiles

This is the most important step. A boomerang comes back because its wings are shaped like those of an airplane, but less streamlined (like in the 1st picture of this step). Believe it or not, but boomerangs come in right-handed and left-handed versions. They are mirror images of each other, and the right-handed one flies counterclockwise and the left-handed one clockwise. That's why you needed to flip the pattern upside down if you are left-handed. Look at the second picture in this step to get familiar with the terminology and to choose which one you will make. The boomerang in the photos is a right-handed version.

Get out your wood rasp or metal file and start removing wood (with this second picture in mind). How much you will say? It depends on a number of factors, including the density of the wood. That's why there are no guidelines printed on the template. You have to experiment a bit until satisfied. It's best to remove some wood, test how it flies, and if necessary remove some more. Removing too much wood can't be undone, so work in a progressive manner. As a general rule, don't go further than half the wood thickness for the leading edge, and don't remove more than 2/3 of the material from the trailing edge. For example, with a 6 mm thick sheet, don't go further than 3 mm for leading edge and leave about 2 mm for trailing edge. If the trailing edge is too sharp, the boomerang will fly unpredictably. The leading edge angle should be about 40 to 45° and the trailing edge angle is more like 20 to 30°. The bottom side remains flat.

When you think you removed enough wood, sand the boomerang a bit smoother (especially if you used a wood rasp, to get rid of those nasty marks). Use the coarse sandpaper first, then switch to medium grit. The leading edges need some round-over. Trailing edges are best left flat. On the bottom side, just give it a quick pass with medium grit to get rid of the sharp edges. Now your boomerang is almost ready for testing. Just one more step to go.

Step 4: Check How the Wings Are Bent

Plywood is rarely flat, so you must check how your wings are bent. Find a flat surface like a stone or glass panel and tap the wings while holding down the elbow (= middle of boomerang). If the wings make a tapping sound, they are bent slightly upwards and that's a good thing because it adds some lift to the boomerang. If on the other hand they make a sound when you flip the boomerang bottom side up, this might make the boomerang fail to return.

There's an easy fix to that: microwave your boomerang for 10 to 15 seconds (depending on the brand of microwave oven) and gently bend the wings up again. If you hear it crack, you've overdone it :-) If your wings were upwards way too much, you can bend them down a bit. The differences are very subtle. If the bending is very noticeable without a flat reference surface, you've probably overdone it.

Step 5: Testing

This is it: the moment of truth. Test your boomerang to see if it needs further adjustments. Of course you'll need to know how to throw it first:

Step 1: Find a big open field with soft terrain (like football field, park, beach etc.). A boomerang easily goes out 25 to 30 m (27 to 32 yards). So make sure you have enough space around you in every direction, and no bystanders in the way.

Step 2: Determine the wind direction (e.g. throw some grass in the air, use a flag) and throw about 45 degrees to the right of the wind (see picture). In other words, if the wind comes from 12 o'clock, throw somewhere between 1 and 2. For lefties, throw somewhere between 10 and 11 o'clock.

Step 3: Hold the boomerang between thumb and fist with the profiled side facing you. Doesn't matter which arm you grip. It's a matter of preference.

Step 4: Throw pretty vertical with a slight inclination to the right (to the left for lefties). Never throw horizontal like a frisbee!

Step 5: Throw with lots of rotation. That's what makes it come back to you, so you can never have enough spin. If it wants to do an extra loop, you probably threw it too hard.

Step 6: It will come back horizontal. Do a sandwich catch by clapping your hands together. It should have slowed down enough to make an easy catch. If it comes in too fast, don't bother catching.

Tips:

- if it lands to the left of you, try throwing it more to the right and vice versa.

- if it lands in front of you, try throwing with more layover (further away from vertical, with a maximum of 45°)

- only throw in low winds. If the wind is a bit too strong, you can make your boomerang less efficient by adding rubber bands to one or both wings. The closer to the tip of the wing, the more effect. Never throw in high winds! The boomerang will come back way too fast and might injure you.

If these written instructions are not entirely clear to you, try watching this excellent video:

Here's a video of me testing my boomerang:

Step 6: Further Modifications (if Necessary)

If your boomerang doesn't fly like you want it to, you can try to vary your throwing style. For example, you could alter the angle to the wind, the height and power of your throw, the angle at which you hold the boomerang or a combination of these. If that doesn't help, there are a few things you can do.

Does your boomerang fly too high or does it fly too low so that it crashes to the ground about midway? This can be adjusted by bending the wings. Bending upwards results in higher flights, and bending down in lower flights.

Does your boomerang fall short? If it tries to make a circle, but slows down and drops dead prematurely, it is most likely that your boomerang does not have enough lift. There are a number of ways to increase lift. Bending both wings up a little more could be enough to generate that extra lift. Do this first because you can always bend them down again. This modification also affects the height of the flight, so if it was already flying high, I recommend doing something else. Removing more wood from the trailing edge will also increase lift. But don't make the edge too sharp. A third option is to remove some wood from the underside of each leading edge, as shown in the picture.

Does your boomerang try to make an extra loop? Try throwing it with less force. It might be that your boomerang has too much lift. You could try to remove more wood from the leading edges. Other than that, there's nothing much you can do except start over. That's why it's important to gradually remove wood and test each time, because you can't undo removal of too much wood.

Regardless of the modification you make: a little goes a long way. Small modifications can make huge differences, so don't overdo it, and try 1 modification at a time.

Step 7: Painting and Varnishing

Once you're satisfied with the flight of your boomerang, you can go ahead and paint it in whatever colors you like. Before you do that, give it a quick sanding with the fine grit sandpaper to get it extra smooth. But be careful not to sand too much, because you don't want to change the flight characteristics anymore. I use acrylic paint, because once it's dry, it doesn't wash away with water (like water color paint for example). Spray cans would also work.

I use a polyurethane wood varnish for protection. I give 1 coat on both sides and let it dry 24 hours. Then I do a quick sanding with the fine grit to get rid of any irregularities. Just a couple of passes will do, because you don't want to sand your paint away. Then you give a final coating on both sides (respect the drying time for each side) and your done!

Step 8: Go Outside and Have Some Fun!

Once your varnish is dry, go out there and throw! Bring your friends and show them how magical it can be to throw something that returns to you.

It would have been impossible to include everything there is to know about boomerangs in this instructable, but feel free to ask me any questions if you run into trouble. If your boomerang doesn't work, it might be tricky to know if it's a faulty design or if it's you who's throwing it wrong. It might be a good idea to buy a returning boomerang first, until you get the throwing right. But beware: a lot of boomerangs you can order online do not return as advertised. I can point you in the direction of some good sellers.

Check out my facebook page (in Dutch) to see some photos and videos of my boomerangs:

www.facebook.com/bossyrangs

I've entered this Instructable to the Outside Contest. I you liked it, please vote for me.