Synthetic Materials Used In The Production Of Boomerangs

For some time now, other materials have been used in the production of boomerangs along with the traditionally used wood. Generally they are synthetic materials which in turn represent a wealth of types and characteristics. However, some few synthetic materials have been fully accepted in the production of boomerangs.
These are :
polycarbonate (Makrolon),
acrylonitrile-butadien-styrole (ABS),
polypropylene (PP),
paxoline (hard paper),
glass-fibre reinforced synthetic materials (GfK),
carbon fibre (CFK).

Below the advantages and disadvantages, the treatment, characteristics and main use are mentioned in detail. The details are based on the experience in the production of boomerangs made by the authors themselves.


Polycarbonate (PC- Makrolon)

Density: 1.2 kg / dm³

Applications: For throwing disciplines such as Trick Catch, Accuracy, Australian Round.

Macrolone is a material as clear as glass and has a shiny surface. It shows high strength, is impact resistant and also very hard. So it is a material which is suitable for the production of boomerangs, but is generally not used very often.

Macrolone is a little hard to work, as it is very hard. It can best be worked using a right-angle grinder and abrasive disk with a 60-80 grain. Of course, filing is also possible, but it takes much more time. For precision work it is best to use sand paper (finely grained paper, dry and wet sanding) or else you can use a scraper which is also highly suitable. It is hardly possible to bend the material when it is cold. To bend it into the desired shape, it must be heated (the bending temperature is reached at approx. 210° C) and afterwards -absolutely necessary- be cooled when it is in the desired shape. The material is available in large sheets, though it can easily be mistaken for acrylic glass.


Polypropylene (PP)

Density: 1,0 Kg / dm³

Application: For throwing disciplines such as Fast Catch, Endurance, Trick Catch, Doubling, Accuracy.

Polypropylene is a thermo-plastic synthetic material, i. e. when heated it gets increasingly smoother and finally begins to melt. It is worked into lots of industrial products. Many commercial boomerangs are also made of polypropylene, so is f. e. "TriFly" by Eric Darnell. This material is appreciated and used very often in the production of boomerangs. It is also quite cheap. As it is slighly heavier than wood, very durable and nearly unbreakable it can be bent easily and can be kept in shape by additional bending, especially in warm weather. With cold weather (< 0 °C) polypropylene gets rather stiff and brittle, though. You should not tune the boomerang too often when it is frosty to avoid unpleasant surprises. It comes in sheets of 1 x 2 m in various colours, but mostly beige/grey or transparent (milky). The common strengths are 4 and 5 mm. Further advantages with this material are that you do not need to wear a protection mask when working the material, as it emits no poisonous vapours and produces almost no dust. The chippings are only grains and flakes

The working on polypropylene is a bit hard. You saw it with a rough fret or jig saw (attention: saw with a low number of strokes per minute, because the material begins to melt quickly and then sticks together). The melting point lies between 160 °C and 180 °C. For the rough profile you should use a rough rasp or a or a power file with grain size 80. When working on the profile you should try to work beginning from the middle and proceeding to the edges and then cut the bulge jutting out with a knife. According to our experience, it is best to use a power file or a small grinding role for the drill when hollowing out the wings. To obtain a smooth surface you should work with an eccentric grinder with grain size 100. Then the surface will look smooth, but is still a little rough and therefore has a good grip. The final piece does not need to be painted, because polypropylene absorbs virtually no humidity. If you work without using electric tools, it will take about 4 to 5 times longer. It is highly recommended to use a scraper, because you can cut away material where it is necessary and you will get a very smooth surface.


Acrylonitrile-Butadien-Styrol (ABS)


Density: 1,0 kg / dm³

Applications: For throwing disciplines such as Fast Catch, Endurance, Trick Catch, Doubling, Accuracy.

ABS is made of styrole with addition of acrylic nitrile and butadiene. It is a very hard and rigid material, but which is also slightly brittle. It comes in sheets in various thicknesses and colours. When ABS is worked, unlike polypropylene it emits a disagreeable gas, which may damage your health.

The process of working is similar to that of polypropylene. As ABS is much harder, it is easier to grind. We recommend using a scraper for the precision work. You need to wear a protection mask. When cutting, you should use a fine saw blade, because the material is very hard and therefore can splinter a little bit.


Paxoline

Density: 1,4 kg / dm³

Applications: For throwing disciplines such as Fast Catch, Endurance, Trick Catch, Doubling, Accuracy, MTA, Long Distance, Australian Round

Actually "hard paper" is the right term. Pertinax, Paxoline, Bakelit are "only" trade mark names. This material was already produced industrially early in this century as one of the first sythetic materials and was used for various utility objects. This material is a layered composite material of paper which is soaked with an adhesive resin layer by layer and then pressed under heat and high pressure, hence the name hard paper. Along with paper, also fabric is used for pressing; the material is then called phenolic. Paxoline has become very popular in the sport of boomerang throwing in the past few years. The main area of application today is the production of printed boards and model construction. Paxoline exists in various qualities and sheet sizes, which may differ with different producers. The colour is mostly brown or sometimes black. The most frequently used strengths range from 1-4 mm. An advantage of this material is that it gets only slightly softer when heated, unlike PP. Also, it is much stiffer and heavier. It is therefore possible to construct larger boomerangs, which is also of great interest for far-throwers (strength mostly 4 mm). With paxoline it is possible to throw up to 30 m farther than with wood. Also, with MTA (1.5 - 2 mm strength) paxoline has been generally accepted. When compared to wood, it shows a higher stability concerning wind as well. And also in the Australian Round and the Trick Catch/Doubling, paxoline in strengths of 2mm (TD) and 3mm (AR) is seen more and more, but not so often in the Endurance, Fast-Catch and Accuracy. The tuning of paxoline objects however is somehow problematic, and now we are talking about a serious disadvantage: the brittleness. The material fails mainly at the border area between paper and resin. When tuning it, the material now and then breaks without "prior warning". Under steam e. g. it is easier to tune boomerangs of strengths between 1.5 and 3mm. The bend mostly keeps its shape. With thin pieces it is necessary to tune again from time to time. Objects of 4 mm strength (far-throwing) are nearly "untuneable". Let´s talk again about brittleness. It is absolutely possible that a piece highly provided with weights breaks after a crash-down. This is the price for you have to pay for rigidity.

As paxoline is a very hard material, as said above, you should use a band saw or a fret saw. You also can use a jig saw, but the consumption of blades is very high. With grinding you can use the usual tools (rasp, file, tape grinder, power file aso.). The dust that arises mainly with grinding is extremely dangerous. There fore you absolutely have to wear a protective breathing mask (with gas and dust filter). We recommend a file or a rasp for the rough working on the boomerang. The worst dirt falls to the floor and does not stay in the air. Highly recommendable is also a scraper, because no dust will arise when working with the scraper.


Fibre Glass Reinforced Synthetic Materials

Density: 1,8 kg / dm³

Applications: For throwing disciplines such as Trick Catch, Accuracy, MTA, Long Distance, Australian Round.

Glass-fibre is a material which combines a high net weight with a small thickness. When sheets are produced, thin mats are put crosswise onto each other, soaked with resin and joined under high pressure. The characteristic features of the glass-fibre reinforced materials´s are determined by the resin and the kind of glass fibres used, and also by their percentage related to the total volume and their arrangement in the material. The stability increases with rising fiber content and the alignment of the fibers in one direction. Construction engineering and printed board manufacturing have been the main areas of application up to now. However, this material is used more and more in the automobile, the aircraft and the machine industries. It is available in sheets with thicknesses of 1-4 mm. Many far-throwers prefer using glass-fibre with thicknesses between 3 and even 4 mm for their boomerangs. Normally the density of glass-fibre is relatively high (see above) compared to other materials. The mechanical characteristics are excellent. It shows high stiffness, high strength and toughness. Glass-fibre reinforced materials are unbreakable. Apart from this, objects up to 2.5 mm can be tuned quite well. There is no need to fear that the material might break. Nevertheless it may happen, but only seldom, that the material is damaged by glass fibres coming off the resin in parts exposed to a lot of strain,when tuning or while throwing (f. e. far-throwing) heavy boomerangs. Microscopic cracks result from this which cause a loss of stiffness. The boomerang then becomes soft and wobbly at the spot concerned.

The material can not be cut without problems because of its high stiffness. However, there are coated fret saw blades with which you also can saw ceramics. They consist of a metal girder on which small granules of hard material are attached to the front edge, and with which you can work very well (highly recommendable). On the other hand you can grind it very well. You can work with a file, a belt grinder or a power file. Because of its toughness it can be tuned rather problematically with thicker strengths (from 3 mm), which means that it has to be bent from time to time (if necessary under heat). It is absolutely necessary to provide sufficient ventilation, when working in a closed room. Also a protective breathing mask must be worn, not because of hazardous vapours but as a protection against the very fine dust. The glass fibres might get into your lung. We also recommend to cover your body to avoid itching.

Carbon Fibre

Density: 1,7 kg / dm ³

Applications: For throwing disciplines such as Accuracy, MTA, Long Distance, Australian Round, Trick Catch, Doubling.

Carbon fibre is a very hard and tough material which can be compared with glass-fibre. It is not as heavy as the former, but much more compact. It is available in sheets of various strengths. However it is very expensive and is therefore not often used in the production of boomerangs. Tuning it is highly problematic. The material is used frequently in the automobile and the aviation industries.

The procedure of working this material is quite similar to that of glass-fibre. Wear a mask when grinding because of the very fine and dangerous dust. Additionally, here are a few tips for tuning, which is very problematic here: You should try to fix the blank in the desired shape, then heat it (approx. 190° C) and afterwards let it cool down. According to experience, it should keep its shape.

Authors:
Dietmar Reinig (D),
Tibor Horvath (CH),
Lorenz Gubler (CH)