Bone not worth it?
I do not think bone is good material for bow ears, unless historical accuracy is you main goal. I think this is also the reason why it fell out of fashion.
According to article i read dog bone has elastic modulus(=stiffness) of 11 Gpa and density of 1400 Kg/m3. 11Gpa is typical elastic modulus for hardwood with half of the weight such as mapple or rowan. I would assume bone double as stiff would also weigth double.
http://www.pubmedcentral.nih.gov/articl ... tid=555578
http://www.lovtrainstitutet.se/en/wood- ... /ronn.html
If you have different opinions or reasons why dog bone is fundamentally different from bone of some other animal, please reply.
According to article i read dog bone has elastic modulus(=stiffness) of 11 Gpa and density of 1400 Kg/m3. 11Gpa is typical elastic modulus for hardwood with half of the weight such as mapple or rowan. I would assume bone double as stiff would also weigth double.
http://www.pubmedcentral.nih.gov/articl ... tid=555578
http://www.lovtrainstitutet.se/en/wood- ... /ronn.html
If you have different opinions or reasons why dog bone is fundamentally different from bone of some other animal, please reply.
jk; Bone was used to stiffen the ears because it was stiff, not because it was flexible. I have fitted bone plates to a grip before but not to ears. This is a lot of work even with woodworking tools. -j-
Elastic modulus is stifness, not elasticity.
What I am trying to say that bone is as stif as hardwood, but twice as heavy, so not worth using in bow ears, where stif and light material is needed.
I made an assumption 50 % stiffer bone would be also about 50% heavier, still making it twice as heavy as wood. (This is a hypothesis based on ... well... Stetson&Harrison-method).
I am looking for arguments against my theory, preferable based on real life results or scientific data about elastic modulus and density of bone.
What I am trying to say that bone is as stif as hardwood, but twice as heavy, so not worth using in bow ears, where stif and light material is needed.
I made an assumption 50 % stiffer bone would be also about 50% heavier, still making it twice as heavy as wood. (This is a hypothesis based on ... well... Stetson&Harrison-method).
I am looking for arguments against my theory, preferable based on real life results or scientific data about elastic modulus and density of bone.
Good ideas how to challenge my thery:
a) Stiffer bones need not be equally heavier than they are stif, because...
b) The animals used as bow material have stiffer and not much heavier bones than dogs, because ...
c) I have made stiffness test with animal XYZ bones and their stifness and
density are:
d) Femoral bones differ significantly from example from leg bones, due to...
e) The is an error on the article you quote ...
a) Stiffer bones need not be equally heavier than they are stif, because...
b) The animals used as bow material have stiffer and not much heavier bones than dogs, because ...
c) I have made stiffness test with animal XYZ bones and their stifness and
density are:
d) Femoral bones differ significantly from example from leg bones, due to...
e) The is an error on the article you quote ...
jk; I don't want to challenge your theory. Enjoy yourself. But if you investigate the sizes of bone reenforcing plates on historic bows, or just existing plates themselves, I doubt if a dog bone would qualify for size.
That bone plates were used for a thousand years to stiffen bow grips and ears is a fact demonstrated by the existence of the numerous finds. That it is less efficient than later bow developments seems clear. But they did not know until they knew.
What would be interesting would be to determine which bones of which animals are useful to the purpose. -j-
That bone plates were used for a thousand years to stiffen bow grips and ears is a fact demonstrated by the existence of the numerous finds. That it is less efficient than later bow developments seems clear. But they did not know until they knew.
What would be interesting would be to determine which bones of which animals are useful to the purpose. -j-
Ok, I found a paper about human bones.
http://biomech2.me.berkeley.edu/Papers_ ... _37_00.pdf
This talks about 16-22Gpa and 430-750Kg/m^3 which is much more stifness/mass than wood, so the usage of bone sounds reasonable after all.
I would assume big animals would have typically much harder bones than humans, so usage of bone in bow ears makes sense after all.
It also looks that the mass and stiffness of bone may not be directly related.
(Or that the measuring method is very different).
http://biomech2.me.berkeley.edu/Papers_ ... _37_00.pdf
This talks about 16-22Gpa and 430-750Kg/m^3 which is much more stifness/mass than wood, so the usage of bone sounds reasonable after all.
I would assume big animals would have typically much harder bones than humans, so usage of bone in bow ears makes sense after all.
It also looks that the mass and stiffness of bone may not be directly related.
(Or that the measuring method is very different).
As I understand it there can be a lot of difference in properties between bones and between different parts of the bone.
What I have been wondering is why the use of bone plates on the sides of the siyahs. From strength and stiffness point of view that is exactly the wrong place. If string wear or something like that was the reason it would make more sense.
TM
What I have been wondering is why the use of bone plates on the sides of the siyahs. From strength and stiffness point of view that is exactly the wrong place. If string wear or something like that was the reason it would make more sense.
TM
The location at the side in maguar bows and the fact that they went out of the fasihion makes me think that they were not worth it. This is why i started to investigate about it.
Someone got the idea that the bones were not there to provide stifness, but stability to the ears and wood can be bent by the weather.
The counter to this is that sinew does not like humidity either.
The counter to this is that sinew does not like humidity either.
There is something else you may consider. The bone plates on old bows were not just plates but actually formed solid tips. In some Chinese bows the tips were not two pieces, but one piece split up the middle.
The bone or antler, there is evidence of both, was selected for strength and the tips were much more slender than could be made with wood. I think that there might be some problems interpreting old bows from modern reproductions. The ears are much thicker and larger than the originals to make them easy to reproduce in modern materials.
The antler that I have used for other purposes seems much stiffer than the equivalent cross section of hardwood. I will see if I can find any reports to back up this subjective impression. The dog bone referenced referred to the head of the femur. This is structurally different from the outside part of the long bones usually used for ear pieces. The same can be said for antler. The method of calculating the elastic modulus must take into account how the piece was prepared. Was it cut longitudinally, did it include only the outside of the bone, etc.
The reasons why styles of bows changed is probably more complex than just efficiency. Fashion and styles of use must have had some effect too. Bone and antler tips were the common style of composite bow over Eurasia for more than a thousand years. They must have had some advantages.
The bone or antler, there is evidence of both, was selected for strength and the tips were much more slender than could be made with wood. I think that there might be some problems interpreting old bows from modern reproductions. The ears are much thicker and larger than the originals to make them easy to reproduce in modern materials.
The antler that I have used for other purposes seems much stiffer than the equivalent cross section of hardwood. I will see if I can find any reports to back up this subjective impression. The dog bone referenced referred to the head of the femur. This is structurally different from the outside part of the long bones usually used for ear pieces. The same can be said for antler. The method of calculating the elastic modulus must take into account how the piece was prepared. Was it cut longitudinally, did it include only the outside of the bone, etc.
The reasons why styles of bows changed is probably more complex than just efficiency. Fashion and styles of use must have had some effect too. Bone and antler tips were the common style of composite bow over Eurasia for more than a thousand years. They must have had some advantages.
Yes, the modern reproductions of Xiongnu/Hun/Magyar bows have much more wood in the siyahs than the originals. In the originals, the wood was only a few mm thick and served as an attachment surface for the bone.
In NE Asia, the bone was horse's (incuding Kulan) cannon bone, thinned down.
In NE Asia, the bone was horse's (incuding Kulan) cannon bone, thinned down.