DIY Bow Project VIII – Do Not Cable Bow With Nylon!

Today, I broke a bow again. It might sound like a failure, but actually it was a new experiment which gave me the results I needed. As a conclusion from the latest test, if you are going to make a real and powerful Inuit bow, do not use nylon for cabling, even though the internet is full of nylon cabled bows!!! In some sources, nylon ropes are considered to be similar with sinew, material the ancient people used in their bows. Still, nylon is too elastic for carrying the tensile stress a bow experiences. So far I haven’t seen any, and I mean any serious strong bow cabled with nylon. Why? For understanding how the proper cabling should work, one can imagine what will happen if a bow is cabled with a rubber band. When the limbs are bent to maximum, the rubber band is not even close to the point where it will stack and pull the tips of the limbs together (compress the wood). If the bow is enough strong, short and/or made of poor material, the tensile stress will break the back fibers and finally the whole bow. Instead, one can imagine a sheet of composite where the back is made of wood and the belly from a sponge. If the wood is bent, its belly becomes compressed, naturally. Because of the relative softness of the belly, the sponge does not stretch at all from any point, it will only become compressed as the neutral plane is fully inside the wood, or in the “backing”. Thus, for making a proper cabling one needs to use a strong cable, not elastic! The dynamic performance, like how fast the bow can cast an arrow or how to avoid the stacking effect during the pull, is another issue, which could demand for moderately elastic materials. But if one wants to use the cabling for its original purpose for securing a bow, a strong cable is the key to success!

So, about the experiment. After I have broke many sorbus bows by using a nylon rope, I tried to make a quick flat pyramid bow from an ordinary pine board. Even though the growth rings were cut, the flat cross sections of the limbs shared the stress more evenly in the wood. Instead of nylon, I used the same material I’m going to use as a string, Dyneema. Dyneema ropes are stronger than a steel wire, but still extremely light. An excellent choice I say! I made strong nocks in the ends of the limbs which I enhanced with a light metal sheets, special wood glue and leather straps. I almost managed to broke the nocks by the high pressure the cabling produced, but I managed to notice the initial failure before it was too late, and make the mentioned reinforcements. Then, for the very first time in my short but serious bow building history, I managed to see compression failures in the wood! The bow did not crack from its back, which means that the cabling really worked! The draw weight was under 30lb, but still this fragile pine board did not snap from its back, what a relief! Next, I need to go to my friend’s forest and find myself a lylymänty, which means a reaction pine. Ancient Finns used lylymänty in their biocomposite bows as a belly. I’m already excited, as it feels quite interesting project to combine two distinct, but northern and ancient engineering master techniques together in the same bow, a Finnish way to use tough lylymänty and the Inuit way to cable bows. And of course, a modern high technology material, Dyneema, will finalize the coming bow 😀 Here are the latest photos about my bow project, enjoy!

IMG_5606 Dyneema cabling for Inuit bow, not nylon. IMG_5612 Dyneema cabling for Inuit bow, not nylon.

Dyneema cabling for Inuit bow, not nylon.

The nock before the final reinforcement.

Dyneema cabling for Inuit bow, not nylon.

Cutting and bending the light metal sheet for protecting the nock from the high cabling pressure.

Dyneema cabling for Inuit bow, not nylon.

Dyneema cabling for Inuit bow, not nylon.

After gluing.

IMG_5793

All the metal sheet, leather strap, Dyneema cabling and string in their places and the bow is in a tillering tree.

Dyneema cabling for Inuit bow, not nylon.

A compression failure, before this fragile pine board snapped from its back! This means that the Dyneema cabling really works, unlike the nylon cabling which is good for making toy bows. Next, I need to get lylymänty in my hands, follow my ancestors, and combine all these ancient northern master techniques together 🙂

2 thoughts on “DIY Bow Project VIII – Do Not Cable Bow With Nylon!

    • Hi, and many thanks for your interest!

      Unfortunately, I made the bow long time ago, why I don’t remember the details anymore. Furthermore, the bow was a failure as you can see in the last image (the compression failures).

      Best wishes, MND

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