Core wood
Helo everybody,
I have some Questions, hopefully somebody can help me.
1 What is the best corewood for an turkish Reflexhornbow ?
2 What is the best wood for shyas for this bow ?
3 Which wood was used traditionally for core and shyas ?
4 Is it important to use light wood for the shyas, because to gain a higher speed of the bow. If yes which kind of wood ?
5 Or is it better to use a heavier wood, to gain a higher stability ?
I have some Questions, hopefully somebody can help me.
1 What is the best corewood for an turkish Reflexhornbow ?
2 What is the best wood for shyas for this bow ?
3 Which wood was used traditionally for core and shyas ?
4 Is it important to use light wood for the shyas, because to gain a higher speed of the bow. If yes which kind of wood ?
5 Or is it better to use a heavier wood, to gain a higher stability ?
There are two articles in the latest Journal of the Society of Archer-Antiquaries on the performance of bows, one by Adam Karpowicz and the other by Professor Bob Kooi.
If I understand them correctly, they imply that heavy siyahs are necessary to be stiff and stable enough to work as intended. This, it is suggested, is the reason that light weight Turkish bows perform no better than well made self bows.
Generally strength in wood is related to density. The denser wood is usually stronger in the same cross section.
I think many bowyers who contribute to this forum would have experience with the different choices of wood and could suggest some good ideas.
If I understand them correctly, they imply that heavy siyahs are necessary to be stiff and stable enough to work as intended. This, it is suggested, is the reason that light weight Turkish bows perform no better than well made self bows.
Generally strength in wood is related to density. The denser wood is usually stronger in the same cross section.
I think many bowyers who contribute to this forum would have experience with the different choices of wood and could suggest some good ideas.
Hello,
I have bamboo and maple for core selection.
Which one is better ?
For Sihays i have maple, is it a good wood for Sihays ?
Or is some other wood for Sihays better then maple.
If yes which one.
Hope for answers from the forum, because there are so many professional boyers here.
I have bamboo and maple for core selection.
Which one is better ?
For Sihays i have maple, is it a good wood for Sihays ?
Or is some other wood for Sihays better then maple.
If yes which one.
Hope for answers from the forum, because there are so many professional boyers here.
Hard maple is the typical wood for Turkish bows. I should add there were several threads about core woods in the past and I suggest to use the search function (I believe it works) to find more info.
I would like to clarify what Bede said:
"If I understand them correctly, they imply that heavy siyahs are necessary to be stiff and stable enough to work as intended. This, it is suggested, is the reason that light weight Turkish bows perform no better than well made self bows. "
This is not quite correct. Bob Kooi said nothing about the weight of bows . Only I wrote about the draw weights, and the conclusion was that all light weight composites do not perform as well as expected and about the same as better selfbows.
Bob Kooi's conclusion was that the composites are not better than selfbows, but only from the design point of view and when the mass of limbs for both is the same. He also goes on to say that since the composite materials can do more work per mass, the composites can be made lighter, and therefore have the advantage over the selfbows.
Adam
I would like to clarify what Bede said:
"If I understand them correctly, they imply that heavy siyahs are necessary to be stiff and stable enough to work as intended. This, it is suggested, is the reason that light weight Turkish bows perform no better than well made self bows. "
This is not quite correct. Bob Kooi said nothing about the weight of bows . Only I wrote about the draw weights, and the conclusion was that all light weight composites do not perform as well as expected and about the same as better selfbows.
Bob Kooi's conclusion was that the composites are not better than selfbows, but only from the design point of view and when the mass of limbs for both is the same. He also goes on to say that since the composite materials can do more work per mass, the composites can be made lighter, and therefore have the advantage over the selfbows.
Adam
Thanks Adam for the clarification. Usually I read your and Bob's articles several times before I get the full implications of what you are writing. It is good to get the author's comments.
I am sorry that in Bob's case, I spend the first and second read throughs concentrating on trying to understand the equations.
I wondered when I read your article whether there was any evidence ,in the case of lighter Turkish bows, of the bowyers using lighter weaker woods in the siyahs (kasan and bash). Assuming the bending parts were weaker, then the stresses on the rigid ends would be less.
I suppose that, if were done, the mass difference might not be significant. In the other scenario, the bowyers might have seen no advantage in experimenting with lighter woods when their main production was heavier bows.
I have seen some odd construction in Turkish bows in the Grayson Collection, like reversed splices, which makes me wonder if they were either more adventurous or more casual than I had thought.
I am sorry that in Bob's case, I spend the first and second read throughs concentrating on trying to understand the equations.
I wondered when I read your article whether there was any evidence ,in the case of lighter Turkish bows, of the bowyers using lighter weaker woods in the siyahs (kasan and bash). Assuming the bending parts were weaker, then the stresses on the rigid ends would be less.
I suppose that, if were done, the mass difference might not be significant. In the other scenario, the bowyers might have seen no advantage in experimenting with lighter woods when their main production was heavier bows.
I have seen some odd construction in Turkish bows in the Grayson Collection, like reversed splices, which makes me wonder if they were either more adventurous or more casual than I had thought.
So, my questions are not anwered yet.
But i will use normal european (austrian) maple for core and Shyias.
Is this OK ?
Thanks a lot
But i will use normal european (austrian) maple for core and Shyias.
Is this OK ?
Thanks a lot
Bede:
You raise a very good point about the possible use of lighter woods for light weight bows. From my experience, it is not usually worth the trouble, because the harder/heavier woods can be trimmed more (as stronger) to reduce mass. And the tips of old bows are already so slim, it is maybe unwise to go any further with weight reduction, especially in the case of a durable hnting bow. Still, this is an area to explore.
I know what you mean about the odd construction in some of the old bows. The bowyers did what worked and saved time, as all craftsmen. I saw, for example, a spline in a cracked tip bent and knots in a kasan (the bowyer took the risk and the bow broke).
I am a bit worried you said you had to read my article more than once. I knew these articles tend to be a bit dense and will try to improve in the future.
Adam
You raise a very good point about the possible use of lighter woods for light weight bows. From my experience, it is not usually worth the trouble, because the harder/heavier woods can be trimmed more (as stronger) to reduce mass. And the tips of old bows are already so slim, it is maybe unwise to go any further with weight reduction, especially in the case of a durable hnting bow. Still, this is an area to explore.
I know what you mean about the odd construction in some of the old bows. The bowyers did what worked and saved time, as all craftsmen. I saw, for example, a spline in a cracked tip bent and knots in a kasan (the bowyer took the risk and the bow broke).
I am a bit worried you said you had to read my article more than once. I knew these articles tend to be a bit dense and will try to improve in the future.
Adam
Adam,
I don't think the problem is with your articles. It's just that there is an explosion of ideas that happens on the first read through and I sometimes wander off the track. Many of the things you are writing about seeing in experiments are things I roughly calculated years ago without any thought of them being demonstrated. Needless to say, you have discovered more things than I dreamed about. Sometimes the fun and excitement get in the way of my comprehension.
In Bob's case the concepts are more difficult for me to follow because he is more rigorously academic in his approach as is fair when trying to reduce to mathematics a complex physical system. Mathematics is like archery, it requires practice and I am not that fit.
I don't think the problem is with your articles. It's just that there is an explosion of ideas that happens on the first read through and I sometimes wander off the track. Many of the things you are writing about seeing in experiments are things I roughly calculated years ago without any thought of them being demonstrated. Needless to say, you have discovered more things than I dreamed about. Sometimes the fun and excitement get in the way of my comprehension.
In Bob's case the concepts are more difficult for me to follow because he is more rigorously academic in his approach as is fair when trying to reduce to mathematics a complex physical system. Mathematics is like archery, it requires practice and I am not that fit.
Stiff siyahs would certainly be more stable than flexible ones but for them to be stable there is a need for torsional stiffness and straight wooden beams are just not very good at that. To get a light weight torsionally stiff structure hollow tubes are used, so far I have not met any (bones were known). That would not be a bad option for a bending beam either.
Some bone overlays on siyahs might have been an attempt at torsionally stiffening them or maybe they were just for wear as most that I have seen on pics are on the sides.
TM
Just some structural thoughts.
Some bone overlays on siyahs might have been an attempt at torsionally stiffening them or maybe they were just for wear as most that I have seen on pics are on the sides.
TM
Just some structural thoughts.