Primitive Archer
Main Discussion Area => Bows => Topic started by: gfugal on February 18, 2017, 12:59:13 pm
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I'm convinced that there are two limiting factors in wood. Tension strength on the back of a bow is the limiting factor for a bow breaking. If you are making a self-bow this should be the main consideration when choosing a bow material. However, if you are making a backed bow, especially sinew, I feel the limiting factor is the wood's compressive ability. It will still probably break on the back before it brakes on the belly, but the reason compression is the limiting factor is because of set. Set represent internal damage to the cell walls in the wood. Once set occurs it is irreversible. It's theorized that set causes hysteresis. The more damage the more internal friction and less spring back capability. thus its compressive ability isn't limiting due to breaking, but its performance. That's why horn bows use horn. The large amounts of sinew allow the bow to bend great distances without breaking, but if it had a wood belly, it would undergo so much compressive damage that it would loose most of its elasticity.
So here's my question. I like backed bows (I might have a self bow phase after I get over my shorter backed bows), so I'm looking for good compressive woods. Does anyone have a list of woods that have great compressive abilities? I know off ipe, and I think I heard juniper is good, but I'm not sure. I don't think I'm quite ready for horn bows. I'm going to wait till I have more experience under my belt. I understand that set is going to happen, but I'm wanting to try and limit it as much as possible.
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Osage, plum and yew are the best I know of. Ipe behaves very well but not as elastic as some other woods.
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Sinew backing makes woods compress LESS, not more.
Second, I'm convinced a lot of bows that look like they failed in tension actually failed in tension when they break. Set is absolutely an issue, but whenever I can't ID another cause like a bug hole or a nick, I wonder. Whenever I see a fret, you can see also that there is a subtle kink or hinge, and that angle is where the back will get over-strained and pop a sliver, and it goes in the next second.
NOW, I was literally on this exact track once and let me tell you what I found out. Tim Baker was right, design is king. I was convinced that if I got super strong backings (bamboo), and super strong belly woods (ipe, bullletwood) that the back would never pop and the belly would never crush and we'd all live happily ever after. I bought brazilwood, granadillo, greenheart, massaranduba, jatoba, coyote, Peruvian walnut, osage orange, ipe, kingwood, pau-ferro, ebony, tropical bamboos, etc... and they all worked, but there was NO super-wood out there.
ANY WOOD CAN BE BACKED. It's all a question of balance, limb width, trapping, and design. I have seen red eolm backed with bamboo. I have backed hickory with bamboo, etc...
Woods offer compressive STRENGTH, and compressive ELASTICITY. Bamboo offers tension STRENGTH, sinew offers tension ELASTICITY. The really important thing is figuring out how to best use the qualities.
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I agree with you springbuck. I honestly can't always tell if something fails in tension or compression first, I have heard they usually fail in compression but it can be hard to tell the difference.
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Sinew backing makes woods compress LESS, not more.
Good catch. What I meant was that a piece of wood can bend much further with sinew than normal, so it can undergo more compression than it would have if it is bent further.
Second, I'm convinced a lot of bows that look like they failed in tension actually failed in tension when they break.
I assume you mean "that look like they failed in tension actually failed in compression"?
Tim Baker was right, design is king. I was convinced that if I got super strong backings (bamboo), and super strong belly woods (ipe, bullletwood) that the back would never pop and the belly would never crush and we'd all live happily ever after. I bought brazilwood, granadillo, greenheart, massaranduba, jatoba, coyote, Peruvian walnut, osage orange, ipe, kingwood, pau-ferro, ebony, tropical bamboos, etc... and they all worked, but there was NO super-wood out there.
Wow you really took it seriously. I'm Impressed. Don't worry I'm not going to go all out and get exotic woods like that. I love the idea of usuing inferior woods. I was just curious if there was some common easily attainable woods that would be better suited for more stressful compact designs.
Woods offer compressive STRENGTH, and compressive ELASTICITY. Bamboo offers tension STRENGTH, sinew offers tension ELASTICITY. The really important thing is figuring out how to best use the qualities.
When you say compressive elasticity, do you mean its speed to spring back to its original shape?
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Oh boy, remind me to keep this short. Disclaimer: I'm not the voice of experience for bow making.
With that said I do know a large amount about wood(s) and not just bow woods.Take what I say as food for thought, obviously everyone must form their own beliefs and from my experience common sense is my best friend. Sometimes I loose my friend, but I try to be mindful of my friend.
This is my approach. About 6 months ago I built my first bow. It was pretty awful. I don't watch TV and rarely Youtube, but I watched one video on a selfbow and I was off to the races. Well after my first aremlts I clearly needed to do more homework. That's how I found this place. I've read tons of threads. I love reading.
I knew nothing about dimensions and the forces at play really my first bow. I'm 6' tall and my draw length is 28". I decided to make my first bow 40", but it looked a little too long so I lopped off another two inches. Hickory self bow. Still have it. It's tiny. I was able to get the draw length to 19" before I thought it might fold. I know about leverage what was I thinking? I wasn't at first. Here is what I did learn.
The bow took very little set actually. I didn't know what set was though. Those hickory limbs are paper thin and the tips are more like pins. I didn't dare even try to bend it until I was near final dimensions. I think it pulls #30 something pounds. I didn't know it then, but not over building your bow and not bending the heck out of it while building it help keep the cells intact. This I can tell you, wood is wood. It is only so strong, resilient, elastic ect. What ever wood you do work with, give to it and it will give back and perform. Burden the wood with extra mass and cracking its spine a hundred times before it's braced and it will slouch, struggle and eventually break.
After this bow I read. I've made six and working on seven. I told myself I want to to build bows this way. I floor tiller enough to get a feel for the particular wood and then by feel, take it to near finished dimensions and if the belly needs toasting, I do all that before ever bending it. Now my bows have come back too light for what I was aiming for but not terrible. They made good gifts for my teenage nephews. I am determined to learn this way. Some feel like it is a bad way to go, but I am confident with my realatinship with 'wood' and as I get a better feel, I'm going to zero in and start producing good stuff.
Bowers say all bows set to some degree, I believe that because it's wood we are dealing with. Just keep exploring and forming your style and don't get down on yourself when you mess up. Reading is a good tool to help with learning curve, experience is knowledge so keep up the good work. I knew I couldn't keep it under three paragraphs, so I might as well tell you what I really think,
Cheers,
Of course I screw up all the time. All the time. I aim for the bullseye though. So there are superior compression woods, but if you don't have that wood, then what? It's all wood.
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NOW, I was literally on this exact track once and let me tell you what I found out. Tim Baker was right, design is king. I was convinced that if I got super strong backings (bamboo), and super strong belly woods (ipe, bullletwood) that the back would never pop and the belly would never crush and we'd all live happily ever after. I bought brazilwood, granadillo, greenheart, massaranduba, jatoba, coyote, Peruvian walnut, osage orange, ipe, kingwood, pau-ferro, ebony, tropical bamboos, etc... and they all worked, but there was NO super-wood out there.
ANY WOOD CAN BE BACKED. It's all a question of balance, limb width, trapping, and design. I have seen red eolm backed with bamboo. I have backed hickory with bamboo, etc...
Woods offer compressive STRENGTH, and compressive ELASTICITY. Bamboo offers tension STRENGTH, sinew offers tension ELASTICITY. The really important thing is figuring out how to best use the qualities.
2 of my most favorite bows I look back to on this site from time to time are "unconventional" combos: A maple backed black cherry bow (https://www.primitivearcher.com/smf/index.php/topic,30235.0.html) and a bamboo backed padauk bow Bubby made a few years ago (http://www.primitivearcher.com/smf/index.php?topic=50466.0). There was even a thread from about a year ago about making bows from unconventional woods (cottonwood, poplar/aspen, etc... pretty sure Plan B made a cottonwood bow that looked pretty sweet).
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Sinew backing makes woods compress LESS, not more.
Second, I'm convinced a lot of bows that look like they failed in tension actually failed in tension when they break. Set is absolutely an issue, but whenever I can't ID another cause like a bug hole or a nick, I wonder. Whenever I see a fret, you can see also that there is a subtle kink or hinge, and that angle is where the back will get over-strained and pop a sliver, and it goes in the next second.
NOW, I was literally on this exact track once and let me tell you what I found out. Tim Baker was right, design is king. I was convinced that if I got super strong backings (bamboo), and super strong belly woods (ipe, bullletwood) that the back would never pop and the belly would never crush and we'd all live happily ever after. I bought brazilwood, granadillo, greenheart, massaranduba, jatoba, coyote, Peruvian walnut, osage orange, ipe, kingwood, pau-ferro, ebony, tropical bamboos, etc... and they all worked, but there was NO super-wood out there.
Me too! Been there done that. There is no magic wood! There are many variables but DESIGN IS KING.
However horn/maple/sinew is pretty close to magic. :) :) and lots of cultures worked that out a long time ago!
ANY WOOD CAN BE BACKED. It's all a question of balance, limb width, trapping, and design. I have seen red eolm backed with bamboo. I have backed hickory with bamboo, etc...
Woods offer compressive STRENGTH, and compressive ELASTICITY. Bamboo offers tension STRENGTH, sinew offers tension ELASTICITY. The really important thing is figuring out how to best use the qualities.
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Incense cedar is a great choice for a compression wood since it handles compression just as well as juniper, but actually grows straight...unlike juniper. Black Cherry is another wood that is considered a compression wood from what I have read. Like other people mentioned, plum is really great for compression and is just a great bow wood all around. The acacia that grows where I live (Acacia confusa) handles both compression and tension excellently and is very similar to rosewood in its properties. Then, there is always compression conifers like compression pine or compression spruce. I have no experience with either, but they were used traditionally by several cultures. If you haven't heard about these, there is plenty of info on compression conifers online and what causes them in nature. From conversations I have had with other bowers, many compression woods have a sluggish recovery time. I think this is another reason why prestressing the sinew into the design is an important factor for compression wood bows.
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You can add locust and mulberry to your list also.
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You can add locust and mulberry to your list also.
Yes you can...
And, I really appreciate the link to those two cool bows.
Actually, though, elasticity doesn't mean the speed with which wood it can return to shape. That's more about hysteresis, which I don't understand very well.
Compression elasticity really means simply that it WILL return to shape when squished.
Some woods RESIST compression well, take a huge amount of pressure to physically compress, and store a lot of energy by being compressed only a little distance, but under great pressure. That's ipe, for instance. These woods are very stiff, and it doesn't take much of it to make a bow belly.
Some woods willingly compress quite easily under moderate pressure, and will gladly squish down for you a good percentage. They too store energy, but likewise readily spring back to full length once the pressure is relieved. These woods are less stiff (easy to compress belly=easy to bend limb), but can often be used in deep, thick designs where the belly compresses a lot. Yew is classic, ERC and juniper follow.
Someone mentioned black locust. Well BL is great belly wood, BUT has a reputation for weakness in compression. What's happening here, I believe, is that locust is STIFF like ipe, but won't hold together as well once it IS compressed. So, locust is (almost) as hard to compress as ipe, but you have to compress it incrementally less, or it will fail.
Take something like elm next. Elm is much easier to compress than locust, but will only handle about the same AMOUNT of compression before it wants to stay squashed on the belly.
I think.
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And, correct, I did NOT mean "tension" twice!
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And I still think we need a sugar daddy to pay for tests as they relate to bow making :D
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Springbuck, nice explanation of compression and response.
I guess that hysteresis understood in the classical way, is just the difference between energy in vs. energy out.
As far as launching an arrow goes, one understanding of hysteresis could be that some of the energy put into the limbs cannot be delivered fast enough upon release to contribute to the continued acceleration of the arrow. The arrow accelerates up to a point where limbs can not make it go any faster, and any remaining energy in the limb is "lost"
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Here is an article I read the other day for work and thought some of you may find it useful, or not.
As you already know wood comes from trees and (some) bows come from wood, the article is fairly on topic.
I added another article for anyone interested, I understand some people here already may know this stuff, it can help to know some of the things discussed in the articles when your out collecting staves, or if using limb wood.
I'm getting at something, I'm not being extremely clear, but there is reason for that. Anyway when your out hunting for staves knowing what spieies you want is all fine and if you find a tree or limb that is straight and minimal knots, good. But those things don't mean your stave is going to be that good. As you know trees are living and they are outside every day and night, through every thunderstorm, wind storm, hurricane etc. They compensate on their own to deal with forces and compression is a force trees naturally deal with. Trees are stuck in the soil and cannot alter the soil to their needed PH. You can tell a lot by looking at many other things besides no knots and a straight piece. Learn how different species deal with compression/tension and use it in your bows. I agree some wood handles compression better than others. But if the cells are abused, having a "good" compression wood doesn't matter.
For me, the issue of finding the perfect wood and wood combinations doesn't carry much weight. If one is so intent on finding it, they should probably just make glass bows because wood will always be wood. Be well,
This is not directed at any one individual, simply some thoughts on the matter.
https://www.dropbox.com/sh/axohbuvobt976p8/AADuwA9miZa7L8nxbDMtmLqEa?dl=
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Weird doesn't even start to describe your ramblings.
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Butt joints are fine with kerotine or horn on the belly as long as the joints are not in the apex bending portion of the limb.Mostly on shorter limbs.Longer ones not quite so dangerous.Otherwise they are doomed to fail in time and I won't try it that's for sure.Too much time gets put into it I don't care to see it blow apart so quickly any more....lol.
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Weird doesn't even start to describe your ramblings.
Ramblings? What gives? It's an honest question, not a rambling. Gross, but honest. I'm surprised nobody has tried this yet. I found another thread where a guy wanted to use deer hoves for the belly, why not toenails? Remember the old saying, "if you don't have anything nice to say, don't say anything at all?"
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Butt joints are fine with kerotine or horn on the belly as long as the joints are not in the apex bending portion of the limb.Otherwise they are doomed to fail in time and I won't try it that's for sure.Too much time gets put into it I don't care to see it blow apart so quickly any more....lol.
Thanks, I'll keep that in mind.
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Tom, you are describing a bow with 3 backings. Once you add another backing the previous backing it becomes a core. Hickory or sinew would make a good backing for a juniper bow. A bamboo lam would not make a good backing but would be a good core in a multi-lam bow. Even a sinew cable would make a good backing for a juniper bow.
If you are serious about making a bow, we are here to help. If you are just blowing smoke then you will get back what you serve up.
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Tom, you are describing a bow with 3 backings. Once you add another backing the previous backing it becomes a core. Hickory or sinew would make a good backing for a juniper bow. A bamboo lam would not make a good backing but would be a good core in a multi-lam bow. Even a sinew cable would make a good backing for a juniper bow.
If you are serious about making a bow, we are here to help. If you are just blowing smoke then you will get back what you serve up.
Thanks for your help. I swear I am not here to blow smoke, I just want answers for the questions that never get asked. I would like to know what you think of the reptile-scale form of gluing a material to a bow's belly? Let's assume we did it with pieces of horn that had been cut in to hundreds of very small, thin plates, and layered them over the bow's belly like scales, 2 or three times over. Has anyone ever tried this before? Seems labor intensive, but I don't know, it might produce a superior bow. It's easier to find small horns than horn that is big and clean enough to make slats for a bow belly.
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I have not seen that overlapping scales type of use on the belly a bow with horn.The butt joint is the only way to join horn that I know of.You don't want it to move though.Forces want to compress.One thing that does work like said earlier is to put the butt joint in the stiffer area of the design of the bow.Not in the apex bending portion.Horn bow makers that make a lots of horn bows have lots of shorter pieces left over.Longer bending limbs are more forgiving to get this done.Say a bendy handle bow for instance.An arch.I would keep that in mind.
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I can obtain unicorn horns more readily than a sufficient supply of finger and toenails and they are easier to work and apply.
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Some time ago, I did an attempt at deducing bow wood properties (tension and compression) from the wood database. See this post (and especially the graphs added) http://www.primitivearcher.com/smf/index.php/topic,50571.msg692147.html#msg692147
Meanwhile, I expanded the list (and figures) to some 100 wood species, and also compiled data for other materials such as bamboo, silk, horn, sinew, flax, jute, sisal, cotton, dacron, steel, ... even fibergl*ss)
Do take this with a good grain of salt (as the primary data may be a bit iffy at times with very limited tests per species, or strongly depending on test conditions such as wood MC), and remember (otherwise Jim Davis will correct me on this): the test on osage was done on green specimens and extrapolated to seasoned wood. So it likely represents an underestimation of its true properties.
But I fully concur with Springbuck: any wood can give good bows, but design (not osage) is king. I once made a shooter out of a board of scots pine at 0.35 SG...
Joachim
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do you mean one of these, Pat?
ht tps://polarfurtraders.com/product-category/narwhal-tusks-%c2%ad-ivory/
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I'm going to relist the woods suggested earlier:
Yew, Osage, Ipe, Black Locust, Plum, Juniper/ERC, Incense Ceder, Black Cherry, Padauk, Mulberry.
(Sorry SpringBuck, I didn't include your long list of exotic woods. I also didn't include very hard to come by, unfamiliar exotic woods in the following list either).
I also am going to propose some potential candidates for good compression woods based off my research from the wood database. They are:
Wenge, Olive, Lemonwood, Hickory, Dogwood, Indian Rosewood, Turkey Oak, Chinaberry, Muninga, Hophornbeam/European Hornbeam, Black Walnut/English Walnut, Blue Ash, American Beech, Yellow Birch, and Slash Pine.
Do any of you have it on good wisdom that any of these woods would make a bad compression wood for bows?
Some time ago, I did an attempt at deducing bow wood properties (tension and compression) from the wood database. See this post (and especially the graphs added) http://www.primitivearcher.com/smf/index.php/topic,50571.msg692147.html#msg692147
Meanwhile, I expanded the list (and figures) to some 100 wood species, and also compiled data for other materials such as bamboo, silk, horn, sinew, flax, jute, sisal, cotton, dacron, steel, ... even fibergl*ss)
Do take this with a good grain of salt (as the primary data may be a bit iffy at times with very limited tests per species, or strongly depending on test conditions such as wood MC), and remember (otherwise Jim Davis will correct me on this): the test on osage was done on green specimens and extrapolated to seasoned wood. So it likely represents an underestimation of its true properties.
But I fully concur with Springbuck: any wood can give good bows, but design (not osage) is king. I once made a shooter out of a board of scots pine at 0.35 SG...
Joachim
I was literally making a spreadsheet when you posted this haha. Thats cool man I'm going to have to look it over. I noticed that you have a "compression before set" value. How did you get that value, since the wood database doesn't have a measurement for it? Did you use the crushing strength value? When I was coming up with that list above I took into consideration the max crushing value, the ratio of MOR/MOE, as well as a new ratio of crushing strength/MOE. The last value isn't a real value but an arbitrary one I came up with, since the wood database doesn't specify a stress modulus of elasticity, wood would not have the same value like most materials. But I figured it would be somewhat proportional. To be considered the list the wood had to score high in all three areas (CS, MOR/MOE, and CS/MOE).
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Does anybody here want to tell me whether this is a futile idea or not? I have a jar full of toenails and fingernails, enough to glue across a short bow several times over. I was thinking about gluing toenails and fingernails to the belly of a bow, like reptillian scales stacked on top of one another, to give compression strength and elasticity. Reason I ask is because a.) it's the same stuff horn is made of and b.) I've seen people gluing 4-5 buffalo horn slats to the belly of a bow, and I was surprised that worked. So thanks for answering all my weird questions.
I don't think its a good Idea for the following reasons
1) I think that's going to be a lot more work than it's worth. It would be like rescaling a fish one scale at a time. It would take forever, plus it wouldn't be very repeatable. It would be easier to buy horn than waiting several years to stockpile a bunch of toe-nails again.
2) Any aesthetic value would be overweighed by its grossness, and you would find it hard to have other people admire your work as much as you do.
3) I think there would be too much glue to nail ratio that any compression value the nail gives will be lossed in the pliable glue. There's no way you would keep all those nails on without a bunch of glue. I imagine it being almost more glue than nail and dried glue probably isn't the best compressor.
I do like how your thinking outside the box though.
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Greg
have you looked at a way to quantify the elasticity component that means so much to bow performance?
Springbuck brought up a good point about it earlier.........
Compression elasticity really means simply that it WILL return to shape when squished.
willie
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It's almost like you guys are trying to re-invent the wheel or use different words to describe the same thing. :laugh:
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Greg
have you looked at a way to quantify the elasticity component that means so much to bow performance?
Springbuck brought up a good point about it earlier.........
Compression elasticity really means simply that it WILL return to shape when squished.
willie
Unfortunately, there isn't really a good value out there that's been maticoulsly measured in wood. The wood database offers a crushing strength value which is the closet thing to it. However, that value is the point the wood breaks not the point the wood takes set.
So here's a breakdown on it. Materials have certain stiffness when undergoing tension and compression. Tension is often called Strain aswell. In the first image, you have a material that is strained. The steepness of the slope of the black line is the stiffness (or modulus of elasticity). Once it undergoes a certain strain it will no longer return back to its original shape, this is called the yield point. (imagine stretching a spring to the point where it stays stretched out). After the yield point a material will be less stiff and can likewise only undergo an additional amount of strain before it brakes. the strain or stress after the yield point to the point of rupture is called the nonelastic region. Every material has different sized nonelastic regions. Metal has a large region, that's why it's so malleable. Wood however does not have a large region, at least in strain, so it breaks shortly after the yield point. These same principles can be applied to compression. Most materials, like metal, have a similar stiffness when undergoing compression and tension, thus their modulus of elasticity under compression is the same as under strain. I believe wood, however, has a modulus of elasticity under compression that's different than the modulus of elasticity under strain. I tried to illustrate this in image 2. It also has a larger nonelastic region in compression compared to strain. The nonelastic region under compression is the stifness of wood after it undergoes set. Those specific wood fibers now have a weaker stiffness than before, hence why set is bad.
The wood database doesn't have the yield points for either tension or compression. It has the modulus of elasticity for tension only and the two rupture points for compression and tension. Since It doesn't have the modulus of elasticity for compression I just used the one for tension to create a ratio. This ratio is a best attempt to determine how far a material will stretch or compress before breaking. The wood database guy did this for tension and calls it the bow index. It's basically the modulus of rupture divided by the modulus of elasticity. I basically did the same thing for compression.
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I'm going to relist the woods suggested earlier:
Yew, Osage, Ipe, Black Locust, Plum, Juniper/ERC, Incense Ceder, Black Cherry, Padauk, Mulberry.
(Sorry SpringBuck, I didn't include your long list of exotic woods. I also didn't include very hard to come by, unfamiliar exotic woods in the following list either).
I also am going to propose some potential candidates for good compression woods based off my research from the wood database. They are:
Wenge, Olive, Lemonwood, Hickory, Dogwood, Indian Rosewood, Turkey Oak, Chinaberry, Muninga, Hophornbeam/European Hornbeam, Black Walnut/English Walnut, Blue Ash, American Beech, Yellow Birch, and Slash Pine.
Do any of you have it on good wisdom that any of these woods would make a bad compression wood for bows?
Some time ago, I did an attempt at deducing bow wood properties (tension and compression) from the wood database. See this post (and especially the graphs added) http://www.primitivearcher.com/smf/index.php/topic,50571.msg692147.html#msg692147
Meanwhile, I expanded the list (and figures) to some 100 wood species, and also compiled data for other materials such as bamboo, silk, horn, sinew, flax, jute, sisal, cotton, dacron, steel, ... even fibergl*ss)
Do take this with a good grain of salt (as the primary data may be a bit iffy at times with very limited tests per species, or strongly depending on test conditions such as wood MC), and remember (otherwise Jim Davis will correct me on this): the test on osage was done on green specimens and extrapolated to seasoned wood. So it likely represents an underestimation of its true properties.
But I fully concur with Springbuck: any wood can give good bows, but design (not osage) is king. I once made a shooter out of a board of scots pine at 0.35 SG...
Joachim
I was literally making a spreadsheet when you posted this haha. Thats cool man I'm going to have to look it over. I noticed that you have a "compression before set" value. How did you get that value, since the wood database doesn't have a measurement for it? Did you use the crushing strength value? When I was coming up with that list above I took into consideration the max crushing value, the ratio of MOR/MOE, as well as a new ratio of crushing strength/MOE. The last value isn't a real value but an arbitrary one I came up with, since the wood database doesn't specify a stress modulus of elasticity, wood would not have the same value like most materials. But I figured it would be somewhat proportional. To be considered the list the wood had to score high in all three areas (CS, MOR/MOE, and CS/MOE).
Chinaberry isn't really a compression wood of any notice...in fact it is hardly a bow wood of any notice despite have a good value on the bow wood index. I've worked with it several times and was never able to get a bow out of it. I think it may be a better wood in different growing conditions than what I deal with here.
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Oh, and Rosewood is an excellent compression wood, but good luck affording a piece of it. I made a black ebony bow some time back and it also made a nice bow, but I was never able to afford to try stressing the design to find out if it is weak in either tension or compression due to the cost of the wood. Like I said before also, Acacia is a great belly wood for compression.
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You can try lots of different woods but I suggest using one good wood and trying different designs . That's what I am doing. All wood is different even in the same tree. Placement of mass is what makes a good bow. Light on the ends ,width, thickness, length. Using one wood will get you there faster in my opinion. O:) but I am asking questions on here just like you. ;D Osage does both well. For me it's selfbows not backed bows at this time. Good luck with you adventure. Arvin
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Since I practice Korean archery, I'd like to know that it's doable to make a bow that does something similar to the synthetic Korean bows without using horn, but [still] with natural materials. I definitely like the much smoother feel of longer static recurve bows, though...
Could incense cedar sapwood or heartwood, sinew backed, be elastic enough to handle a 32" draw with a 50"ntn static recurve? (Korean design). Oh, and with something like 12" of resting reflex.
Sinew backed bamboo - yes, I saw one... but it's a bit strange since bamboo is so much stiffer in compression than sinew is in tension? Or is it? While horn seems to have similar stiffness in compression than sinew in tension.
Look at this crazy thing. It bends so much. Wonder how much hysterisis it has.
https://www.youtube.com/watch?v=mjd5gQx5uQU#t=1m9s
Would something that has a stiffness similar to sinew not be able to bend more, if sinew backed, than something stiffer?... .. Wouldn't materials with different stiffness, laminated, result in more shear force? So could incense cedar or juniper be better than bamboo sinew backed? (unless bamboo is less stiff in compression than I think)
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Greg
Unfortunately, there isn't really a good value out there that's been maticoulsly measured in wood.
Yes , I agree. At least not a value that tells us bowyers much about energy storage before set reaches an unacceptable level.
I have found listings for "work to maximum load" or WML in some of the older data. It seems that when wood was used in applications where it was commonly strained to the point of failure, (mine timbers and vehicle parts come to mind), the WML was useful. I have not yet found a good (mathematical) explanation of how the value was obtained, but quite a bit of testing was done at one time, and if a way was found to examine those values and perhaps make an adjustment for more moderate levels of strains, the "obsolete" data might be useful for our purposes.
A recent thread where WML is discussed some.
http://www.primitivearcher.com/smf/index.php/topic,59651.msg828984.html#msg828984
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Since I practice Korean archery, I'd like to know that it's doable to make a bow that does something similar to the synthetic Korean bows without using horn, but with natural materials. I definitely like the much smoother feel of longer static recurve bows, though...
Could incense cedar sapwood or heartwood, sinew backed, be elastic enough to handle a 32" draw with a 50"ntn static recurve? (Korean design). Oh, and with something like 12" of resting reflex.
Sinew backed bamboo - yes, I saw one... but it's a bit strange since bamboo is so much stiffer in compression than sinew is in tension? Or is it? While horn seems to have similar stiffness in compression than sinew in tension.
Look at this crazy thing. It bends so much. Wonder how much hysterisis it has.
https://www.youtube.com/watch?v=mjd5gQx5uQU#t=1m9s
Would something that has a stiffness similar to sinew not be able to bend more, if sinew backed, than something stiffer?... .. Wouldn't materials with different stiffness, laminated, result in more shear force? So could incense cedar or juniper be better than bamboo sinew backed? (unless bamboo is less stiff in compression than I think)
Loon, not to be weird about it, but horn is a natural material. You could alternatively use bone. Possibly from a cow leg or giraffe or something with long legs and enough bone (you can easily find these bones online). Traditionally whale rib was used by some Arctic tribes to my knowledge. Horn has 8X the compressive ability of most wood. It isn't so much that cedar or juniper could or couldn't bend as far as horn ( I doubt it would, but who knows), it goes back to the graph listed above. At some point, even if the wood is still bending, it is going to deform and start taking a lot of set. Sinew offsets this, but that is sort of also missing the point. The woods ability to perform at maximum capacity before taking set and losing strength is what you are after. A lot of the really short incense cedar or juniper bows aren't ever pulled much past 22-24''. This is stressing the wood just to the point you are getting the most out of it while at the same time utilising the sinew as much as possible by stretching it as far as possible. If you are trying at a full 30-32'' korean draw, horn or bone is really the best option. Bamboo has been used as both a core and belly material for these bows, but my understanding is that it is heavily heat treated to the point of blackening to increase its compression and help it resist set. Bamboo after all takes more set than any wood will, so this is important. If you are looking to make a bow out of something rather than horn, try heat-treated bamboo. You could even add a mulberry or maple core like the Koreans do to give it additional stiffness. It would be lighter than a hornbook since horn is quite heavy. It would be a cool project and I don't doubt you'd learn a lot, but I think horn is still far more durable and practical.
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Bone? Bone doesn't actually take a lot of bend. Korean bows have been made with bamboo bellies. Bamboo doesn't really take more set than wood. It wouldn't make a fishing rod if it took set.
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Do you think this would make a mighty fine, ligntning-hunting bow? I'm trying to make something real, real evil that I can hunt lightning with.
Good luck with your toe nail covered lightning hunting bow. I'm sure these guys will get to the bottom of it for you. Broad head design is MOST important for killing lighting.
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Bone? Bone doesn't actually take a lot of bend. Korean bows have been made with bamboo bellies. Bamboo doesn't really take more set than wood. It wouldn't make a fishing rod if it took set.
If I take data on the elastic modulus for bone, plus ultimate tension and compression strengths (from this 1974 paper http://dx.doi.org/10.1016/0021-9290(74)90018-9), it indicates that bone fails in tension at an elongation of c. 0.8% (which is less than most bow woods), and fails in compression (beyond the yield point) at a compression of nearly 1.2%, which is better than any wood. but it's darn heavy (SG c. 2.0). For its mass, it stores about the same amount of energy (in compression) as good bow woods. Overall, I'd say it's not that good that you should consider it as a belly material, unless you have no wood to work with, like inuit people did.
I see no reason why you'd use bone if horn or even wood is an option.
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Chinaberry isn't really a compression wood of any notice...in fact it is hardly a bow wood of any notice despite have a good value on the bow wood index. I've worked with it several times and was never able to get a bow out of it. I think it may be a better wood in different growing conditions than what I deal with here.
That's helpful info. It's odd how some woods would appear to be good but end up being just crummy. Like I mentioned earlier there is no real data for yield points in compression or even tension out there. all there is, is failure points and stiffness. It's possible Chinaberry has excellent compression & tension strengths (meaning it takes a lot of bending to break them), but its yield points may be pathetically low. This would mean its elastic region would be small. If that's the case then once it does pass those yield points it becomes a mushy mess. A strong mushy mess, but a mushy mess nonetheless. Either that or it's an inconsistent wood. Rather than having low yield points, the wood is actually week with low failure points depending on growing conditions. Where under the right conditions it could be a good bow wood like when it was measured for the wood database, and in other conditions its not.
Oh, and Rosewood is an excellent compression wood, but good luck affording a piece of it. I made a black ebony bow some time back and it also made a nice bow, but I was never able to afford to try stressing the design to find out if it is weak in either tension or compression due to the cost of the wood. Like I said before also, Acacia is a great belly wood for compression.
Yeah, I was hesitent to included some of the exotic woods I did list; like Wenge, Olive, Lemonwood, Indian Rosewood, Chinaberry, Muninga, and maybe even turkey oak. I chose to include them because they were still somewhat obtainable, although maybe expensive, and because they were fairly well known woods. I know Indian Rosewood is supposed to be easier to get than Brazilian Rosewood, or Madagascar Rosewood. Madagascar Rosewood would be very very expensive, if you could find it at all. It currently has a restriction on it keeping it from being cut down anymore. I'm sorry I forgot to put acacia on the list. I'll go back and modify it.
You can try lots of different woods but I suggest using one good wood and trying different designs . That's what I am doing. All wood is different even in the same tree. Placement of mass is what makes a good bow. Light on the ends ,width, thickness, length. Using one wood will get you there faster in my opinion. O:) but I am asking questions on here just like you. ;D Osage does both well. For me it's selfbows not backed bows at this time. Good luck with you adventure. Arvin
There is some wisdom in that. That way you can eliminate bow wood as a variable when you're trying to hone your skills and figure out where you went wrong. Unfortunately, some of us live in locations that make it hard to come across yew or Osage, unless we bought it and had it shipped. I live in Utah, and the only good bow woods I know of that grow natural in the wild is Utah Juniper and Mountain Mahogany. Both of which I haven't been able to find any data on. I originally posted this to determine what woods were good so if I happen to run into an assortment of woods when collecting from arborists, landscapers, the city, neighbors, or what have you that I would know beforehand what I would be working with. Even if did end up liking juniper or mountain mahogany I don't know if I could keep to using it alone. I'm a fickle person when it comes to preferences, and I enjoy making things different ways and from different material, even unusual material. But that's just me. Osage and Yew are usually right at the top of the lists for either compression or tension. They work, and everybody knows they do. No sense changing if you don't wan't/need to.
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Since I practice Korean archery, I'd like to know that it's doable to make a bow that does something similar to the synthetic Korean bows without using horn, but [still] with natural materials. I definitely like the much smoother feel of longer static recurve bows, though...
Could incense cedar sapwood or heartwood, sinew backed, be elastic enough to handle a 32" draw with a 50"ntn static recurve? (Korean design). Oh, and with something like 12" of resting reflex.
Sinew backed bamboo - yes, I saw one... but it's a bit strange since bamboo is so much stiffer in compression than sinew is in tension? Or is it? While horn seems to have similar stiffness in compression than sinew in tension.
Look at this crazy thing. It bends so much. Wonder how much hysterisis it has.
https://www.youtube.com/watch?v=mjd5gQx5uQU#t=1m9s
Would something that has a stiffness similar to sinew not be able to bend more, if sinew backed, than something stiffer?... .. Wouldn't materials with different stiffness, laminated, result in more shear force? So could incense cedar or juniper be better than bamboo sinew backed? (unless bamboo is less stiff in compression than I think)
I'm not going to say it's not possible. As it's clearly been done. What's not clear in that video is whether the wood was damaged at all in compression. It may have passed its yield point but the sinew may be keeping it from manifesting any set. If that's the case most of the poundage of the bow is coming from the sinew, with the belly serving simply as a shpae holder.
One thing you have to understand with stiffness is that it doesn't determine how far a limb will bend. That's determined by the ratio of its yield-point/stiffness. Unfortunately, we don't have data for yield points so we have to make due with faiulure-point/stiffness. If a wood's yield point is low, It doesn't matter if a material is really stiff or not. All that means is that it will be easier to break once it bends beyond a certain point. Lets look at two bow woods for example: Yew and Black Ironwood. Ironwood is more than twice as stiff as yew, yet has a breaking point just barely more than yew. what this means is that the yew will be able to bend almost twice as far as the ironwood. However, the ironwood would be almost twice as heavy a draw than the yew for the same amount of material. But even then, I still don't think too much importance should be given to stiffness. In the example of the yew and Ironwood, you could easily make yew just as heavy of a draw by simply adding more material. That way it's just as strong as a bow, and it can bend further if you needed it too. This is way yew bows tend to be thicker depth wise than say something like osage.
To answer your question about different stiffnesses of sinew and belly material, the answer is pretty much it doesn't matter that one is stiffer than the other. the stiffnesses of the two materials have no influence on each other unless you change the depth thickness to accommodate them. What strains the material is not the poundage of the bow but the amount of stretch or compression each outer section undergoes. This is solely determined by how far it is bent, and how far the material lies depthwise from the core of the bow. The further from the core the more it will be stretched or compressed. That's wy thicker bellies undergo more tension. Not because some magical property of the wood changes when there's more of it. It's just that the outer fibers are being asked to do so much more and they fight back that much stronger.
Lets say you had two bows of equal depth, both sinew backed, with the only difference being that one had a very stiff belly material like horn and the other didn't. Lets also say both bows were bent the same distance. Because their depths (limb thickness) were the same the stiffer bellied bow would have to be much stronger. You would think then that the sinew on the back of the stiffer bow would be under more stress. This isn't the case. The sinew on the back of both bows are both equal distances from the core, and are both being stretched just as much for that bend. The only difference is the belly material. The material on the belly of the stiffer bow does not like to be bent, so that extra poundage is coming from it alone as it fights to restore its self to an unstressed profile.
So don't worry about a stiffer belly material overstressing the sinew. In fact, it would stress it less, because the depth would decrease for the same poundage than it would be with a less stiff material. Plus the nice thing about sinew is its designed to take a beating as far as stretching is concerned. It's the recoil in the achelies tendon that essentially propels an animal off the ground when it jumps. Could you imagine building a bow that could shoot an arrow as heavy as a half an elk several feet off the ground? yet sinew in the achelies does that every time the animal jumps.
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Bone? Bone doesn't actually take a lot of bend. Korean bows have been made with bamboo bellies. Bamboo doesn't really take more set than wood. It wouldn't make a fishing rod if it took set.
Bone would only be used with sinew similar to horn and it does take compression very well. It was recommended as a substitute for horn and horse ribs were what was suggested. I haven't used it, but others have with success. I am getting my information on bamboo set from the potential bow wood's list by Tim Baker who notes it takes more set per mass than any hard wood. I always have issues with it taking more set than wood as well when making un-heat treated all-bamboo bows, so I agree with the statement. Being there are over 1,500 species of bamboo, I am sure there is a lot of variation in there though and the bamboo used for fly-rod making is Tonkin bamboo which is an exceptional species.
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I see you focus quit a lot on this "bow wood index" of the wood database.
http://www.wood-database.com/wood-articles/bow-woods/
This index assumes that the best bows are made from woods with low modulus of elasticity (bending easily with little force) and high modulus of rupture (allow them to bend very far, in tension).
Basically, those are not the qualities I would look for in a bow. I want both high MOR and MOE: such bow would (for the same bow mass) require more force to be pulled (hence storing more energy per drawn inch) AND be allowed to be drawn far. And you want this not only in tension, but also in compression.
Unfortunately, there is this trade-off between the two: either you have high MOE and low MOR, or the opposite. That's what the regression line in both my earlier graphs show.
And you also need to take wood density into account: bow mass is critical to performance, hence Steve Gardner's mass principle. That's why I divide all MOE and MOR data by the specific gravity (SG), so as to standardize. Only then can you really compare wood qualities.
Now, when you take all available bow making materials and compare them on this scale, you can guess what comes out as the best bow-making stuff... We don't say its name on this forum, it belongs to the dark side of archery... >:D >:D >:D
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I haven't read through the whole thread, but just felt the need to explain why the reptile scale idea won't work.
Why do you think reptile and fish scales overlap?
It is to provide flexibility/mobility! Which is exactly what you don't want in a bow belly.
As the others have said a butt joint is fine as the joints just compress against eachother rather than sliding over eachother as would happen with scales.
Del
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I see you focus quit a lot on this "bow wood index" of the wood database.
http://www.wood-database.com/wood-articles/bow-woods/
This index assumes that the best bows are made from woods with low modulus of elasticity (bending easily with little force) and high modulus of rupture (allow them to bend very far, in tension).
Basically, those are not the qualities I would look for in a bow. I want both high MOR and MOE: such bow would (for the same bow mass) require more force to be pulled (hence storing more energy per drawn inch) AND be allowed to be drawn far. And you want this not only in tension, but also in compression.
Unfortunately, there is this trade-off between the two: either you have high MOE and low MOR, or the opposite. That's what the regression line in both my earlier graphs show.
And you also need to take wood density into account: bow mass is critical to performance, hence Steve Gardner's mass principle. That's why I divide all MOE and MOR data by the specific gravity (SG), so as to standardize. Only then can you really compare wood qualities.
Now, when you take all available bow making materials and compare them on this scale, you can guess what comes out as the best bow-making stuff... We don't say its name on this forum, it belongs to the dark side of archery... >:D >:D >:D
I would prefer the ratio of Tension-Yield-Point/MOE-under-tension, but considering there is no data that I know of giving yield points, I rely on the Bow Index. For the woods I listed, the bow index was less of a factor, I considered the ratio of crushing-strength/MOE. Again I would prefer the ratio of Compression-yield-point/MOE-under-compression, but unfortunately, there is no data for that. I think we're saying similar things, it's just that we have different priorities we focus on. I agree with you that the best material would be in the upper right corner of your graphs. You, however, put more emphasis on the weight and stiffness of a wood. I look mostly at the flexibility (how far it can bend without breaking). Really it depends on your design in mind. The reason I think max flexibility is most important is because I have short backed bows in mind, like the one loon mentioned in his post. It doesn't matter if the material is lighter or stiffer in those situations if it ends up breaking or getting ridiculous amounts of set. However, if you have a long bow with a draw length that's less than 45% of its length then the wood won't be bending that far so you can look at other factors such as weight and relative stiffness compared to density and give less priority to its max flexibility, just as long as it's flexible enough. I really don't give much attention to the stiffness of the material, only the ratio of failure point and stiffness. In my mind, if one material is less stiff but more flexible you can remedy its lack of stiffness with more material.
You mentioned in your post that you updated the graph to include other materials like sinew, horn, and etc. Is there a way that you could send me that data by chance? I would love to look over your work and see what I could figure out from it. Maybe I'm not giving enough emphasis to wood density like you suggest. I have personally never read the mass theroy. Mybe someone could send me a photo copy of it from the book.
Bone? Bone doesn't actually take a lot of bend. Korean bows have been made with bamboo bellies. Bamboo doesn't really take more set than wood. It wouldn't make a fishing rod if it took set.
Bone would only be used with sinew similar to horn and it does take compression very well. It was recommended as a substitute for horn and horse ribs were what was suggested. I haven't used it, but others have with success. I am getting my information on bamboo set from the potential bow wood's list by Tim Baker who notes it takes more set per mass than any hard wood. I always have issues with it taking more set than wood as well when making un-heat treated all-bamboo bows, so I agree with the statement. Being there are over 1,500 species of bamboo, I am sure there is a lot of variation in there though and the bamboo used for fly-rod making is Tonkin bamboo which is an exceptional species.
Bone may do compression very well since that's what its designed for. It isn't bendable at all, since it is brittle and will break in tension. I'm wondering if its elastic in compression though. It's very stiff in compression that's for sure, which is good for its purpose. However, I wouldn't think it has a very large elastic region of compression, but joachimM gave data saying that it can compress 1.2% which is more than most woods can compress before breaking. I'm not sure what the nonelastic region of bone is, I'm guessing its pretty small since I have a hard time imagining bone taking set. based off the data I would say it could be a good belly material if done right, but have never personally tried. If I were to do it, I would have it be thin enough that it's purely on the belly and doesn't cross over at all into the back where it would undergo tension. I would also make sure your bow is long enough. Jim Ham tried it once but he said that the bow stacked like crazy. Tim baker showed in the TBB that if a bow stakes its not because its near its breaking point but because of the string angle. So maybe thats why his stacked not because of the bone. Its also possible though that bone has a nonelastic region that is stiffer than the elastic region. This isn't the case with wood, but it would explain why Jim said it felt like it was going to explode. JoachimM do you know how bone behaves after it has passed its yeild point in compression? does it get stiffer or weaker like wood?
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Greg,
There is a good thread about the mass theory in the archive library, and a search of badgers posts should return something.
A google search similar to mass theory site:http://www.primitivearcher.com may also return good results.
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You should want to care about the stiffness and elasticity, and mass:
if elasticity is the only thing you care for, try making a bow out of cooked spaghetti. very flexible, doesn't take set!
Second, mass: you mention if it doesnt draw enough, just add more material (more spaghetti?). But I bet you wouldn't be satisfied with a bow weighing as much as a 60# normal bow, but drawing only 30#. Mass (and mass placement) is critical to bow performance.
As for the bone information: the information I gave was on the yield point, not the failure. The load-displacement graph: check it out here
http://dx.doi.org.sci-hub.cc/10.1016/0021-9290(74)90018-9, look for figure 7b and the text just under "results" on the next page.
And for the database update: you can find it on my google drive: https://drive.google.com/open?id=0B3YYA3Sr_3gqMm9oWkExTjdiOTg
Joachim
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I have no idea about the technicalities of using the bone as a belly material apart from seeing it being used by horn bow makers from time to time as a belly material. I've never made a horn bow or a bone bow, but am wanting to try bone at some point out of curiosity. Most horn bows are made with a wood core to stabilize the horn and as I am guessing, also to reduce the overall weight of the bow since horn is also very heavy. I would do the same with a bone bow if I were to make one. I would make the belly lam as thin as I could get away with to reduce weight and have a wooden core. The thinner the material, the more likely it will bend, so I am guessing this would take care of any bend issues with the bone. Like I said, my information is very incomplete on bone, I am just throwing the possibility out there since others have used it and you seem interested. Biggest problem would be getting long enough bone and reducing it to size. Doesn't exactly split well of cut easily!
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Regarding bone:-
It does flex a bit and it isn't all that brittle, I s'pose it's a matter of degree.
I remember playing footbal (soccer) and sliding into a tackle. I got the ball but the other guys legs caught me and I felt the whole leg bend sideways, just like floor tillering a bow. Fortunately it didn't go bang.
Del
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Bone is a composite material, consisting of a matrix of collagen (which gives the flexibility) surrounded by calcified tissue (hydroxyapatite; which gives rigidity). Remove the calcium and you get a floppy, porous rubber-like core. Remove the collagen, and you have a brittle stick.
Bone is three times as heavy as most bow woods, but also about three times stronger (according to the paper I discussed). So per unit of mass, you get about the same compression strength as wood. You can compress it a bit further than wood, in theory, according to these lab results, that may not represent actual conditions in which we shoot bows.
Antler is also bone, by the way. Ask people making antler bones how they perform.
Many people will talk about "elk horn" (including the bowyer in the video below), but antler is bone, not horn.
http://www.primitivearcher.com/smf/index.php?topic=49910.0
https://www.youtube.com/watch?v=STP-n-s_Ji4
Check this one out, especially
https://www.youtube.com/watch?v=JmfYJBha7SU
and https://www.youtube.com/watch?v=LpkLs_3jpI4 (shooting at 5:39): wood handle, working limbs of caribou antler and a sinew cable (see 7:45 for details)
And also see this thread from 2010: http://www.primitivearcher.com/smf/index.php?topic=20199.0
quoting KenH: "I would guess that if bone were a reasonable substitute for horn, this whole conversation wouldn't be taking place, because we'd have seen lots of examples"
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My recommendation is to quit researching spend the time making money to buy a good Osage stave say 100 plus shipping and build a bow dude. You have the cart before the horse. I don't know you and your skill level with working wood . Working wood is the only way to learn it though. Arvin
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Yep. Unless there is some as yet undiscovered super wood out there we're just juggling the known woods with design factors.
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Bone is a composite material, consisting of a matrix of collagen (which gives the flexibility) surrounded by calcified tissue (hydroxyapatite; which gives rigidity). Remove the calcium and you get a floppy, porous rubber-like core. Remove the collagen, and you have a brittle stick.
Bone is three times as heavy as most bow woods, but also about three times stronger (according to the paper I discussed). So per unit of mass, you get about the same compression strength as wood. You can compress it a bit further than wood, in theory, according to these lab results, that may not represent actual conditions in which we shoot bows.
Antler is also bone, by the way. Ask people making antler bones how they perform.
Many people will talk about "elk horn" (including the bowyer in the video below), but antler is bone, not horn.
http://www.primitivearcher.com/smf/index.php?topic=49910.0
https://www.youtube.com/watch?v=STP-n-s_Ji4
Check this one out, especially
https://www.youtube.com/watch?v=JmfYJBha7SU
and https://www.youtube.com/watch?v=LpkLs_3jpI4 (shooting at 5:39): wood handle, working limbs of caribou antler and a sinew cable (see 7:45 for details)
And also see this thread from 2010: http://www.primitivearcher.com/smf/index.php?topic=20199.0
quoting KenH: "I would guess that if bone were a reasonable substitute for horn, this whole conversation wouldn't be taking place, because we'd have seen lots of examples"
I agree, antler bows are essentially bone bows and prove that bone is a usable belly material, but they also highlight the issues of using bone as a material. For one, it is far more time consuming to prepare than either wood or horn. Second, it has more complications due to the difficulty of getting appropriate material. Third, and most importantly, it does not perform as well as horn. I think this all sums up why we don't normally see it used in bows. Thanks for the detailed info by the way!
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How do you know which side of a bone has the collagen material and which side is hard? I know antler is easy because it has a spongey core that makes up the back of the bow, so you scrape the horn on the outside which is the belly. What part of the bone should I scrape?
I disagree that bone is more difficult to work. It is hollow so all you have to do is find a piece that is near to the dimensions you want your bow to be (ribs?) and engrave or saw it longitudinally. Bone is also very easy to work by abrasion as compared with wood (try using rocks to abrade wood that hasn't been dried for 30 years). Wood on the other hand is a treacherous, spiteful, sick, unforgiving, hatefuuuuulllllllllllll material
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Sounds like you have a firm opinion of something you've never worked with. ;)
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Sounds like you have a firm opinion of something you've never worked with. ;)
I have worked with bone before. Made all kinds of stuff from it, with nothing but a flint burin and a few river stones. What're you talkin bout, Bertha?
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Why are there so many people named Patrick on this website?
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Sounds like you have a firm opinion of something you've never worked with. ;)
I have worked with bone before. Made all kinds of stuff from it, with nothing but a flint burin and a few river stones. What're you talkin bout, Bertha?
Well you don't know which side is porous and don't realize that the collagen is dispersed throughout. Are you a vegetarian? Most people could glance at a T-bone or a dog bone and figure that out.
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Sounds like you have a firm opinion of something you've never worked with. ;)
I have worked with bone before. Made all kinds of stuff from it, with nothing but a flint burin and a few river stones. What're you talkin bout, Bertha?
Well you don't know which side is porous and don't realize that the collagen is dispersed throughout. Are you a vegetarian? Most people could glance at a T-bone or a dog bone and figure that out.
Well, that was my concusion, but bat-boy Joachim M over here said that if you scrape off too much collagen you'll get something stiff, and that if you scrape off too much of the stiff stuff, you get something wobbly. If the collagen is dispersed throughout, that should be impossible. No matter where you scrape you're going to have a piece of bone with roughly equal parts collagen and equal parts hydroxyapatite. It's not like antler where you have a visible sponge layer (in the core). So, which know-nothing am I supposed to lend faith to here? Wil it be JoachimM, or PatM? Why are there so many people here with a surname that starts wifh the letter "M?"
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I don't believe he used the word scrape. You need to soak a bone in vinegar to remove all but the collagen since it is dispersed throughout. That's what makes it a natural composite.
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Wow! I am out of here . This is waaaaayyyyy over my fat head. Arvin
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I don't believe he used the word scrape. You need to soak a bone in vinegar to remove all but the collagen since it is dispersed throughout. That's what makes it a natural composite.
I don't believe he said vinegar, either. He also did not say that collagen was dispersed throughout, but that it was "surrounded by" a layer of calcium-phosohate tissue, implying bone is similar to antler which has a spongey, soft core.
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Regardless, you gave me an idea for the Next Generation Bow. Cut out two bone limbs and submerge the surfaces that will become the back of the bow in vinegar for 1 week. This creates a revolutionary new bow material with the optimal combination of a stiff belly and flexible back. Just add sinew. Going to patent this right now, in fact.
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I don't believe he used the word scrape. You need to soak a bone in vinegar to remove all but the collagen since it is dispersed throughout. That's what makes it a natural composite.
I don't believe he said vinegar, either. He also did not say that collagen was dispersed throughout, but that it was "surrounded by" a layer of calcium-phosohate tissue, implying bone is similar to antler which has a spongey, soft core.
You know people aren't obligated to make everything perfectly comprehensible on here. Are you the guy who got banned a few months back?
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My recommendation is to quit researching spend the time making money to buy a good Osage stave say 100 plus shipping and build a bow dude. You have the cart before the horse. I don't know you and your skill level with working wood . Working wood is the only way to learn it though. Arvin
Yep. Unless there is some as yet undiscovered super wood out there we're just juggling the known woods with design factors.
I'm not going to deny that yew and osage are the best wood. But what i don't understand is when people here say you shouldn't branch out to different materials. After all, fiberglass is far superior to osage or yew yet we aren't satisfied in making just fiberglass bows. Why can't it be the same idea for lesser known woods? Fiberglass makers shouldn't say we should only use fiberglass, likewise fellow primitive bowyers shouldn't say we shouldn't use other woods.
And i am working on a bow right now. See the "why did i get set" topic. I've made three bows in the last 4-5 months plus going to school full time and workong full time. Researching won't hurt anything.
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I didn't narrow it down to those two woods.
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I didn't narrow it down to those two woods.
Right, there are other frequent woods: hickory, HHB, ERC, Dogwood, Maple, Hackberry, Black locust, and others I'm forgeting. I shouldn't have got so defensive. I just get tired when i want to try something new and people say i should just do it how its been done.
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I don't believe he used the word scrape. You need to soak a bone in vinegar to remove all but the collagen since it is dispersed throughout. That's what makes it a natural composite.
I don't believe he said vinegar, either. He also did not say that collagen was dispersed throughout, but that it was "surrounded by" a layer of calcium-phosohate tissue, implying bone is similar to antler which has a spongey, soft core.
You know people aren't obligated to make everything perfectly comprehensible on here. Are you the guy who got banned a few months back?
No, I'm not. What do you think about the Next Generation Bow idea? Would that work? Perfectly comprehensible answers are appreciated.
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I don't claim to know it all by any means.i do think out side the box. I have some 50# selfbows that get over 170' per second with a 500 grain arrow. You take the same arrow thru a 50# glass bow of the same design you might be a bit surprised. Glass is not that superior. It's the design in the glass bows and the ease to achieve it that makes it more desirable to the bowyers and the manufacturer. There is nothing easy about all wood bows that perform. Young man I encourage you to keep thinking outside the box so to speak. Also it's good to hear about young people working there way thru collage. Mass is mass and the placement of it is where you get the performance. It's got to hold together! So if you hat a barrel of toe nails and you could mold them together where they would stay together you might have a super bow. I don't know? Keep in mind you are on a forum of a bunch of old farts that have been building bows for a while . We are here to help if we can. Arvin
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There really isnt a huge difference between the modern long bow broadhead record and the wood bow record. 213 meters with the modern and 210 meters for the primitive. They are using a skinny fast flight string while we are using a heavy linen string. Their arrow is about 50 grains heavier which ballances out the string difference.
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I don't believe he used the word scrape. You need to soak a bone in vinegar to remove all but the collagen since it is dispersed throughout. That's what makes it a natural composite.
I don't believe he said vinegar, either. He also did not say that collagen was dispersed throughout, but that it was "surrounded by" a layer of calcium-phosohate tissue, implying bone is similar to antler which has a spongey, soft core.
Hey Mr Dulaney, hold your horses. No need to get too excited either ::). We don't claim to know THE truth, we just try to help O:) O:).
So as for the bone: the collagen is made of microscopic fibers, and around and between these stacked fibers you have the calcium-matrix. So each flexible fiber is truly surrounded by the hard stuff. Within a bone, you get denser bone at the outside (logic, there it needs to work most) and less dense bone inside, just like in antlers.
Have a look at how bones are constituted https://www.slideshare.net/abraml02/bone-tissue-12606392.
You could demineralize bone (slide 16: https://image.slidesharecdn.com/bonetissue-120419125640-phpapp01/95/bone-tissue-16-728.jpg?cb=1334840382), and end up with a floppy result. It ain't too easy though to get it right.
Do I think that is the cradle of the next-generation bow? Nope. But do try. And if it works, tell us. If it fails, too.
Joachim
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Sometimes on here when people ask for advice they hear what they don't want to hear too.If it is'nt liked the thing to do is try it or not try it.We'll still be here.
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I don't claim to know it all by any means.i do think out side the box. I have some 50# selfbows that get over 170' per second with a 500 grain arrow. You take the same arrow thru a 50# glass bow of the same design you might be a bit surprised. Glass is not that superior. It's the design in the glass bows and the ease to achieve it that makes it more desirable to the bowyers and the manufacturer. There is nothing easy about all wood bows that perform. Young man I encourage you to keep thinking outside the box so to speak. Also it's good to hear about young people working there way thru collage. Mass is mass and the placement of it is where you get the performance. It's got to hold together! So if you hat a barrel of toe nails and you could mold them together where they would stay together you might have a super bow. I don't know? Keep in mind you are on a forum of a bunch of old farts that have been building bows for a while . We are here to help if we can. Arvin
Right, that makes sense, as long as the design is good and it works for the material its going to be a shooter. Its just how easy it is to get the material to work with the design. I'm just saying that other woods could make great bows too, they just will be harder to make work than osage, and i don't think your doubting that. As was mentioned I shouldn't get upset if the advice given isn't what i was looking for. Clearly you guys know what ypur doing, its just that I like to do things differently. Bytheway, those are some impressive numbers. Would it be cool if you PM me a bow that did that?
I would love to see its side profile unbraced and at full draw, as well as the force curve. I am also curious about the tapering of the limb width, and the mass of the bow. What material did you use for your string, and how heavy and long is it? I hope thats not too much to ask. I believe you, i'm just super eager to examine the specs of a real fast bow so i can know what to expect from a piece of wood. For some reason all the bows i've speed tested have come out pretty inefficient. Even the store bought ones, which has puzzled me.
PS heating a bearl of Toe Nails sounds disgusting. The smell would be enough to kill me. Haha i'll leave that task to someone else.
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The invitation extends to anyone who can provide that info for a 50lbs or les bow that can shoot a 500 grain arrow faster than 170' per second. Specifically the sode profile and force curve is what i'm really interested in examining.
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wonder if dave mead's bamboo horsebow would do
edit: probably easier with a long draw too, like over 31"
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The invitation extends to anyone who can provide that info for a 50lbs or les bow that can shoot a 500 grain arrow faster than 170' per second. Specifically the sode profile and force curve is what i'm really interested in examining.
Greg, read chapters 5, 7 and 8 in TBB4 (design and performance revisited; The mass principle; Flight archery). All your answers lie there.
To boil it down: the easiest way to make such a bow (IMHO) is a broad pyramid bow with pencil-thin nocks (Ishi-pyramid style bow, TBB4 p 125. But there are many ways to skin a cat... The mass principle and thin outer limbs will get you there.
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It might can be done from any wood with proper placement of mass. But here goes on some Osage .69 " long Total mass 23-26oz.1-1/2 at fades, 10" handle, 1-1/2to 1-1/4 at mid limb , 1/4-1/8 at tips. 3 in reflex that holds not taking set. Tillered to 50# at 28" will get you there. It's that easy. I don't know what kind of grade that will get ya but the rest of the info you can get on your own. It should not take to many bows.lol Arvin
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TBB4 p 125
What I hate about the e-book is that I can't find the corresponding page >:(
Eventually found it though. "A Combined Ishi-Pyramid Bow". The corresponding location number is 275.6...
I'd rather do a stiff handle though
edit: no. unless i changed something requiring a different design (ie a longer bow), but for a mid-length mid-draw length as the book says, slightly bendy is excellent
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TBB4 p 125
I'd rather do a stiff handle though
Why? Just because or do you think there's a good reason that a stiff handle will be better? Put it another way: why change a proven design, and risk making it less good?
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Bone? Bone doesn't actually take a lot of bend. Korean bows have been made with bamboo bellies. Bamboo doesn't really take more set than wood. It wouldn't make a fishing rod if it took set.
If I take data on the elastic modulus for bone, plus ultimate tension and compression strengths (from this 1974 paper http://dx.doi.org/10.1016/0021-9290(74)90018-9), it indicates that bone fails in tension at an elongation of c. 0.8% (which is less than most bow woods), and fails in compression (beyond the yield point) at a compression of nearly 1.2%, which is better than any wood. but it's darn heavy (SG c. 2.0). For its mass, it stores about the same amount of energy (in compression) as good bow woods. Overall, I'd say it's not that good that you should consider it as a belly material, unless you have no wood to work with, like inuit people did.
I see no reason why you'd use bone if horn or even wood is an option.
Do you know what the elastic modulus under compression was for the bone? I can't read the article cause you have to buy it. Do you have it downloaded?
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One thing you may want to consider with bone is that it is designed or evolved to be continuously repairing itself from stress. It degrades under stress and then needs to heal from that.
Trees and horn grow and then don't do much after that.
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Do you know what the elastic modulus under compression was for the bone? I can't read the article cause you have to buy it. Do you have it downloaded?
Sorry. Go to http://sci-hub.bz and enter the doi of the article, start reading!
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Basically, those are not the qualities I would look for in a bow. I want both high MOR and MOE: such bow would (for the same bow mass) require more force to be pulled (hence storing more energy per drawn inch) AND be allowed to be drawn far. And you want this not only in tension, but also in compression.
Exactly. This is what stiffness is all about. Some of those woods they listed ARE stiff, elastic, and rupture resistant,, like osage, but most woods are "pick any two" kind of deal.
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Go to http://sci-hub.bz and enter the doi of the article, start reading
:) :) :)
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"Regardless, you gave me an idea for the Next Generation Bowsubmerge the surfaces that will become the back of the bow in vinegar for 1 week."
I hope you are kidding, but ni case not.... yes, bone is a composite material, with heavily calcified tissue and collagenated tissue all mixed in together on a MOLECULAR scale. You can't remove either by scraping, you can only expose more of the same, which is both types mixed in. The spongy part is trabecular bone, and the hard, solid part is cortical bone, and they are different structures laid down by the bone cells (called osteoblasts) but are mostly made of the same materials.
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Greg, only a few die-hards that I know of willingly reject other woods besides osage and yew. Almost everybody on this site hold.....preferences? at the worst. I'll tell you what, though, osage acts basically like it WANTS to be a bow.....
I don't fault you at ALL for your quest for knowledge. As I said elsewhere i did it myself. I'm like a big 4 year old and always have to ask "why?". It's the ADHD, man!
BUT, I can also add that much of what I wanted to know was being told to me by some of the old timers way back then. The issue was they would tell me, but never tell me why. Regardless, much of it was simply correct and I could learn why as easily by following their advice as by questioning it. I'm not scolding, I promise. and, i still love theoretical and didactic learning. We've all done one little thing that nobody else has, but it's mostly a method, not so much a major tweak of the final product.
Most of my own quest and questions went like this, "I wonder why they say you can't just do it like this.?.......BLAM! Oh, that's why! Hmmmm...." But, I say, never stop!
Hang around a while and we'll have this whole conversation again next year.
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TBB4 p 125
I'd rather do a stiff handle though
Why? Just because or do you think there's a good reason that a stiff handle will be better? Put it another way: why change a proven design, and risk making it less good?
Yeah, but it's only drawn 23".. 23*2=46, and total handle area is 8, so 54 minimum for a stiff handle bow, and it's 59 1/4" ntn. But it's still very fast at that draw length.
lol, all this osage worshipping, it still breaks if you don't chase the ring properly? more than hickory. And no one seems to think it can make a good bow 50" long with 32" draw length, if sinew backed, while bamboo apparently can.. (i know it's a grass)
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I am not sure anyone is still interested in considering the bone option due to the weight of the bone, but if you are interested in where the idea came from, you can look at the video below on how to construct an asiatic composite bow by Jeffery Schmidt and John McPherson on youtube part 3 when they are discussing belly material. Antler, ribs and bone are mentioned as usable replacements for horn, but again, it is doubtful they would work as well as horn as mentioned by others comments on this thread. However, it is worth noting that it isn't a far-fetched idea. https://www.youtube.com/watch?v=h2Ehd1FXsVk
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loon,
You can only convince people that its possible to make a good 50" bow drawing 32" by actually making it. If you think so, you gotta start making shavings.