1) Use the right blade for the right material.

 

If you are cutting paxolin, lexan, or glass fibre use the blades recommended for metals. Also ensure that you use the finest finish blade that you can buy - the one with the most teeth per cm. This can make the difference between a nice clean cut or your materials shattering.

 

When cutting anything else use a blade recommended for wood. This is obvious for ply but less so for ABS or polyprop. Anyone who has struggled through ABS with a blade recommended for metal will know that the material melts and then reseals itself behind the blade... but if you use coarser blades recommended for wood you avoid this problem.

 

Also, whenever economic, replace your blades as they do wear out.

 

2) Remember that most shapes are made by people drawing round boomerangs.

 

If you draw round a boomerang you will be adding a millimetre to each side of the boomerang. Therefore if you faithfully follow the shape you will end up with a boomerang bigger than the original. The width of the wings will be larger and the weight will be slightly higher. You may find that it doesn't quite make the distance, or it falls short. Therefore make allowances for the fact that the pattern has come from a boomerang that has been drawn around. Otherwise you can see that the logical conclusion is that copies of booms will get bigger and bigger each generation.

 

Also remember that the opposite allowance needs to be applied to holes. If people draw within a hole they will leave a pattern that under-represents the size of the hole.

 

3) Make photocopies of the shape of a boomerang

 

This can either be to save drawing round a boomerang or to replicate the copied pattern of a boomerang. Making photocopies will allow you to cut out a pattern from the paper and stick it to the material you are going to cut the blank from. It also allows you to mess around with scaled enlargements and reductions which can yield good results when you want to translate a shape to either thicker or thinner materials, e.g. you want to take a shape that works in 3mm pax and recreate it in 2mm pax, therefore you may want to experiment with a reduced overall size of the boom.

 

4) Make your boomerangs upside down

 

This not a homage to Australian roots, just an observation of where the chipping occurs. When you are cutting pax, thin pax in particular, you will find that there is a tendency for the underside to crack and splinter more than the upper-side when cutting. Seeing as you are more likely to remove material from the top of a blank to make an aerofoil, then the chips are more likely to fit in with the intended shape of the topside of the boomerang.

 

5) Weigh your boomerangs

 

It is not enough to say that you have made a perfect copy of an Ice Runner from 4mm 10 ply. The density of the materials that you have used may be very different from the original. The best plans give the weight of the finished boomerang and you should hope to end up with a similar result.

If you do not end up with a similar result and you end up with a lighter boom the way head is not simple. NB I have found this to often be the case with plywood that the grades of ply that us Brits have used are less dense than the referenced Finish Birch Ply that the Germans have been using. So we find our booms don't quite make the distance, and we decide the best thing to do is weight them up.... but however we weight this will effect the behaviour of the boomerang: e.g. add weight to the tips of the arms and the rotation will increase increasing the distance and the lift; if  we add weight to the centre we will cause the boomerang to layover more and therefore be more likely to fly upwards in the last third of it's flight.

 

The material isn't everything but having the right density really helps and this is perhaps why the original Nightglow Trifly's are so sought after as they have the correct density for the 20m boom events.

 

6) Beware (or Be Aware ) of the grain and bend of your material

 

Almost every material will have a grain which will mean that it is easier to bend in one direction than another. The result of this for boomerangs can be that depending on how you cut your blank out certain wings will either be relatively stiff or floppy. This is even true of pax and it is a factor that I am sure makes the difference between booms cut out of the same sheet of material. I cannot quite put my finger on it .. and invite comments on how we should use this info....

 

7) Use the natural bend in your sheet of material

 

If the sheet has an inbuilt bend make sure it complements the expected tuning of the blank that you are cutting out of the material. The less tuning you have to give to boomerang and the less it needs tuning as a result of seasoning the more stable the tuning will be.

 

8) Don't throw a boomerang away until you understand why it does not fly

 

It takes effort to make a boomerang, and it is disappointing if it does not fly as you had imagined. Therefore you owe it to your self not to throw the boom away until you find out what you did wrong. Often if you make the airfoils a little sharper you can turn a bad boom into a reasonable boom.

 

9) Tune in the oven first

 

If you know the rough tuning of the boom you are making it is best to try and set it after you have heated the boom in the oven. For ply this is a melting and resetting of the glue, and for pax it is insurance against breaking. The latter point is one that took me a long time to learn...... But one February weekend I noticed that I was breaking more booms than usual through tuning and suddenly it all made sense - materials are more pliable when they are hot and less pliable when they are cold. Doh..

 

 

10) Experiment with shape

 

There are a lot of folk out there who understand the theory of why a particular shape does this and another shape does that. That said, you can, and should follow your hunches as to what should fly. All the good makers of boomerangs admit to tons of failed experiments.

 

Go on - have a go !