Hopefully eventually, not yet, cable backed bamboo bow

[pcoutin]

I am buying some flat bamboo to try to make a long cable backed static recurve, hopefully my first "real" bow. An experimental one at that.. could say it'd be sort of eclectic, mix of Inuit, bhutanese, and Han/central asian long ear bow, I guess.

I plan to make it without V-splices, just gluing and wrapping bamboo on top of bamboo to make the static ears. Or would V-splices be really worth it? Something like this. Though setback handle could be nice. And I think it will be around 61", not 87" long.



Would like it to be takedown, would make the bamboo rough around the handle so it can be held together just by cord wrapping.

Maybe 87" is way too much. 75" or so is likely more than enough, and something like 60" is probably enough for 33" draw if done right... No idea how heavy I could make it.

With inuit style cable backing of nylon braided cord, which is stretchy like sinew. Don't know if small bridges for the cable would be worth it (about 1/4" tall??..) maybe I could make taller ones out of fir as well as a handle reinforcement out of fir I have laying around.

Hopefully this thread won't be a total waste :p So, terrible idea or no?

Should start with something simpler... but... but.. might start with something like a bhutanese bow with no ears or recurves, cable backed with no bridges. Hopefully that bamboo is good for bows if cable backed.

my source of inspiration: http://i178.photobucket.com/albums/w241 ... bow002.jpg

[Bede]

Nylon is much more stretchy than braided sinew. Artificial sinew is great for sewing and binding but it is totally unsuitable for tension members in a bow. I wouldn't even use it for bowstrings. You could try it by pre-stressing it, but it is very elastic. Dacron might work since it is a less stretchy form of nylon.

Tennis racquet gut (the real thing made from sheep intestines) is about 1.27 mm in diameter and it very good at storing energy. I made a bowstring for a heavy flight bow out of it and it lasted for years.

Twisting up sinew string is another pathway, though you would end up selling more than you would use.

[pcoutin]

I don't have nylon but I have hemp, maybe I will try reverse twisted craft store hemp. It doesn't stretch at all, but if very reverse twisted, maybe it will? The bamboo breaking or not will tell me :p Seems like Amazonian archers might've used plant fibers for cable backs.

You probably don't want a string to store energy? Though that's good to know, maybe it's a good natural alternative to polyester (dacron) and silk. I've read that nylon has properties very similar to sinew and a paper claiming that it could serve as a substitute, but after handling a piece of sinew I can see your point. It's not nearly as stretchy as the nylon thread I have. May try some thicker nylon cord or gut if the hemp doesn't work out.

I've started carving out some bamboo, but the only knife I have here is not sharp enough. I need a rasp. I won't make a static tipped bow first, just a simple D bow, cable backed.

[mikekeswick]

Hemp fiber has the opposite properties to what you require. Hemp is great for bowstrings but not for a cable back as it has very little stretch, this will cause your bows belly to be overstrained.
Bede's suggestion of using tennis racket string is a very good idea.
Nylon is too stretchy and would require a large amount of it to give the resistance to stretching you need.

[pcoutin]

Thanks a lot for the suggestions. But all the tennis racquet string that is not synthetic I've seen after a bit of looking up is a bit too expensive for me. Maybe I could try making gut strings and cord from sausage casings. Hope it's cheap. Just read that cattle gut such as from cows is the strongest, and what's used for tennis racquets. Wonder how the stretch and strength/weight compares to rawhide strings, and where they were traditionally used for bowstrings.

http://www.primitiveways.com/cordage_backed_bow.html

This is nylon..

http://paleoplanet69529.yuku.com/topic/19738

This is also nylon, and does not look like a lot. Have you had issues using nylon for cable backed bows? I think if I "apply" the nylon while the bow is reverse-braced, it should do fine.

..Wonder how polyester (dacron=polyester) braided cord would do. I could just buy a spool of nylon and a spool of polyester and see what happens. Wish I had more time for this stuff.

[Bede]

The best tennis racquet gut is made from sheep. 3 Rivers Archery sells gut for hafting, but it is not really suitable. It has variations in width and thickness that make a good looking binding but are not effective for a cable backing. Sausage casings a pig intestines, if they are natural. To make a string out of the full intestine, you need to split it from end to end to make a long ribbon. After that you stretch and twist it while wet. Drying under tension reduces its tendency to stretch more.

Lots of things were used for backing. It depends whether the backing is designed to store energy or to prevent the bow from breaking. Rawhide was useful for breakage prevention, but did not contribute to the energy storage and its weight slowed the limbs down. Polyester/dacron bowstring material would be a good experimental start. It should perform well enough to make a bow that will shoot and won't break. Later if you get access to better material, you can always replace the backing. That is an advantage of a cable backed bow.

One of the articles made some points on the Inuit not being able to make hide glue because of lack of resources. This is probably not accurate since, if you can cook, you can make animal glues. Two things would lower the usefulness of hide glues in the Arctic: temperature and humidity. I have seen a harpoon arrow with glued parts and glue impregnated sinew. When I asked about the effect of sea water on the glue, I was told the surfaces were covered in seal fat to protect it. Harpoon arrows were a summer weapon when the temperatures were not so bad. However you can see that a whole bow backed with glued sinew might be much more vulnerable.

If you use vegetable fibers such as linen or hemp, you have to accept that the rest of the bow will be under compression since the cables will stretch much less than the wood and it will be compressed. It is like the reverse of a sinew backed antler bow where the antler won't compress much so the sinew does all the work in tebsion. This is not to say there were not solutions found to these problems. A musk ox horn bow was found in a grave and baleen bellied bows are known too.