Author Topic: Small diameter bamboo backing  (Read 6197 times)

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Offline waterlogged

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Small diameter bamboo backing
« on: July 20, 2010, 10:45:43 pm »
Well, I was away from my workshop for a summer, and had nothing with me but my ferrier's rasp, a hickory board, and an old axe the people I was staying with let me borrow. Then, for some odd reason, I got it in my head to make a recurve. The grain couldn't stand it, so I looked for a backing. No good fabric available, and only a home depot down the street.

I had thought before of splitting the more power fiber rich parts out of small-diameter bamboo, and all the home depot had for bamboo was 6ft long, and about 3/8 thick at the end (tomato stakes, I think, good arrow material). So I gave it a shot with some two ton epoxy.

And now, I finally have time to post it. It came out about 45lbs at 26 inches, and is 58 inch nock to nock. The lower limb is bending a bit much, but I got to the point where it didn't seem to change no matter what I did, so I stuck with it.

The set isn't too bad, and stands at 1/4 to a 1/2 inch of reflex left after about 2 to 2 1/2inches.

Overall, the backing no more difficult than any other bamboo backing, as you don't need to do much after splitting the power fibers out. You'd need a bit more work if you were using tightbond or some other not gap filling glue to flatten the individual strips, but it's not nearly as tough as flattening a bigger piece of boo with just hand tools.

Here's the album of pictures http://picasaweb.google.com/watertoiceXI/BBH?authkey=Gv1sRgCLrV-oeAlsG1aw&feat=directlink, sorry, I seem to have forgotten what type of image code this board likes.

Some mornings it just doesn't seem worth it to gnaw through the leather straps. ~Emo Philips
I do not know with what weapons World War 3 will be fought, but World War 4 will be fought with sticks and stones. ~Albert Einstein
Location: Northern California and Northern Nevada

Offline aznboi3644

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Re: Small diameter bamboo backing
« Reply #1 on: July 21, 2010, 02:25:45 am »









Offline waterlogged

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Re: Small diameter bamboo backing
« Reply #2 on: July 21, 2010, 03:43:57 am »
Thanks aznboi, figured someone would have a better idea than me.
Some mornings it just doesn't seem worth it to gnaw through the leather straps. ~Emo Philips
I do not know with what weapons World War 3 will be fought, but World War 4 will be fought with sticks and stones. ~Albert Einstein
Location: Northern California and Northern Nevada

Offline Josh

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Re: Small diameter bamboo backing
« Reply #3 on: July 21, 2010, 10:51:45 am »
Cool Bow.  Bookmarked for July Laminates too.  :)
“The trouble with quotes on the Internet is you never know if they are genuine.” —Abraham Lincoln

Offline Frode

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Re: Small diameter bamboo backing
« Reply #4 on: July 21, 2010, 12:20:10 pm »
I like this!  Very interesting!  And resourceful, too!  As I have yet to do anything with bamboo, I'll happily show my ignorance... what is the power fiber in bamboo, and how did you go about extracting it?  I've seen pictures of radial splitters turning large diameter bamboo into wide slats, but how do you work with the small diameter?  And how did you prep it prior to gluing?
Thanks,
Frode
If it doesn't rap the lintel, it might not be a longbow.

Offline Del the cat

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Re: Small diameter bamboo backing
« Reply #5 on: July 21, 2010, 12:59:06 pm »
Bravo, great to see someone trying something different!
It's too easy to make a bow if you have perfect materials...the challenge is in the stuff like you've done here.
Nice lookin' bow, those straight recurved tips look good (would that make them restraight tips?  ::))
Del
Health warning, these posts may contain traces of nut.

Offline Orkraider

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Re: Small diameter bamboo backing
« Reply #6 on: July 21, 2010, 01:52:00 pm »
This is one of the more interesting things I've seen in a while.  That kind of bamboo is cheaply available at the big box stores near me. I might have to give that a shot. 

If you wanted to post more detail about the process, I for one would be delighted. =)

Bow looks great, too.
Riley, Saint Paul, MN

Offline waterlogged

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Re: Small diameter bamboo backing
« Reply #7 on: July 22, 2010, 02:24:06 am »
Josh -- thanks, though I don't think I have much of a chance with robustus' chariot bow, that thing is impressive! lol

Frode -- No problem, the power fibers are the very outer fibers of bamboo, and are named such because all the near magical stuff you hear about bamboo is almost solely due to them. If you play around with some bamboo (any type or size, really) you'll notice the difference right away. In fact, the bamboo gets weaker as you go closer to the center, which is originally why I was thinking of doing this; to cut out the weak stuff that didn't do much. As to how to extract it, I'll explain below.

Del -- yeah, I kinda put that recurve a little far in the limb, and ignored the rest. Theoretically it is supposed to make it better, and man can you feel the let off when the string lifts off them! So apparently it works. As for calling them something, I think I'll just go with severely procrastinated reflex.

Orkraider -- Thanks, I like the fact that almost every place I've been too has this stuff easily available, no excuses to not do bamboo backings. I'd be more than happy to post something. Below is a small intro to getting the strips.

First what you'll need is some smaller diameter bamboo. The stuff I'm using here is sold in 6 or 5 ft stalks at Home Depot in packages of a half dozen or so, but I'm sure almost any bamboo that size would work.

You'll want a rather sharp knife, the sharper the easier this will be. Start where I've indicated in the first picture; right at the node. You'll want to start the blade under the little lip and head that direction, as that'll make it much easier.

Cut inwards at a small angle by just pressing on the back of the blade while it's under that lip. It'll be difficult for the first 1/2 inch or so, and look like the second picture. It'll then suddenly split, and now what you cut will be straight along the grain and come off in a neat strip, instead of a curled little end.

As you're progressing down the shaft, make sure you keep the knife angled inwards, like in the fifth picture. Otherwise the split will run out and you'll end up with a very short strip. Too much inwards pressure, though, and you'll end up with a hunk of bamboo instead of a strip of power fibers. A bit of practice, and you'll be able to do it easily.

The split will end at the next node. And that's that! I tend to make some things more complicated than they sound, so I'd say get out and give it a shot, it's really rather simple. The other bonus of working with this stuff is that it's as cheap as dirt.

To glue them on the bow, just bend them a bit and clamp them flat when gluing. A gap-filling glue might save you a headache, as there are several "gaps" in mine, though I'm sure you could avoid them if you were so inclined.

Well, good luck if you try, and definitely post the results!



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Some mornings it just doesn't seem worth it to gnaw through the leather straps. ~Emo Philips
I do not know with what weapons World War 3 will be fought, but World War 4 will be fought with sticks and stones. ~Albert Einstein
Location: Northern California and Northern Nevada

Offline aero86

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Re: Small diameter bamboo backing
« Reply #8 on: July 22, 2010, 10:55:51 pm »
this might be a good idea for the pieces of bamboo that just wont make arrows.  what'd you use to glue those with?
profsaffel  "clogs like the devil" I always figured Lucifer to be more of a disco kind of guy.

Offline waterlogged

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Re: Small diameter bamboo backing
« Reply #9 on: July 23, 2010, 06:00:07 pm »
I glued them with two ton epoxy, mainly because it was what was there and had some gap filling properties. I'm sure if you took a bit more time prepping it, you could use any glue you wanted. The gluing can also be done one strip at a time, which makes it much less of a production than gluing the whole strip at once.
Some mornings it just doesn't seem worth it to gnaw through the leather straps. ~Emo Philips
I do not know with what weapons World War 3 will be fought, but World War 4 will be fought with sticks and stones. ~Albert Einstein
Location: Northern California and Northern Nevada

Offline aero86

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Re: Small diameter bamboo backing
« Reply #10 on: July 23, 2010, 07:57:16 pm »
what do you guys think about taking those poles they use for tiki torches and using those to make strips?  might get longer strips out of it.  ive personally thought about using them for backing..
profsaffel  "clogs like the devil" I always figured Lucifer to be more of a disco kind of guy.

Offline denny

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Re: Small diameter bamboo backing
« Reply #11 on: July 23, 2010, 11:09:50 pm »
Good Idea, Like the long static tips. cool  looking bow. I'll bet it shoots snappy. Denny