Hi All
This is try 3 at this Asiatic style bow.
As is often the case in my life it seems like third time lucky is just the way it works.
The core is the same as last time -- 2 full length bamboo flooring lams that are 1.5mm thick, plus a central lam 3mm thick and 600mm long and tapered to nothing at both ends and a 150mm long 3mm thick stiffener both ends tapered to nothing. Handle thickener is a bit of some sort of Eucalypt from a glut off a truck.
As last time I used the technique of applying glass rovings as you would sinew and on this bow I used it on both back and belly.
I am extremely pleased with the result. It draws nice and evenly and the limbs have no tendency to twist. I got lucky with my guess on how much rovings to use on each side and managed to get almost my ideal draw weight of 55# at 28".
I have now shaped the handle area enough to shoot it and is a joy to draw having that elastic feel that is characteristic of this type of bow. The interesting thing about the draw weight is that the first inch of draw is 5.5# so the early draw weight is very high and it gives the impression of very high arrow speed. I will be interested to chrono it and see if I am correct.
So as I said -- Third time lucky -- I am now going to put permanent string guides on it and shoot it enough to be sure that it will continue to work without problem but I am fairly confident that it is a happening thing.
Graeme
Try 3 Asiatic Horse Bow
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Try 3 Asiatic Horse Bow
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Hi Graeme,
Well done!
The bow looks good and hopefully it will be a good shooter. The alternative backing to bamboo would appear to be the answer as I believe we have been trying to push bamboo past its physical limits. Having said that I will give bamboo another try as I have got it to work successfully on two previous attempts. Please keep us posted on the performance figures.
Daryl.
Well done!
The bow looks good and hopefully it will be a good shooter. The alternative backing to bamboo would appear to be the answer as I believe we have been trying to push bamboo past its physical limits. Having said that I will give bamboo another try as I have got it to work successfully on two previous attempts. Please keep us posted on the performance figures.
Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
Hi Daryl
Yes my conclusion is that bamboo is better in compression than the best wood but not nearly good enough for the extreme loads of short Asiatic bows. The resin I used has a compressive strength of 110 MPa which is more than twice the best wood available and the resin and glass together has a compressive strength of about 300 MPa . Unfortunately I can not work out how strong horn is as the only figure I can find is in TBB where it is said to withstand 4000 pounds per square inch but this is only 27MPa which makes no sense as this is only about half as strong as Ironbark -- if anyone has a figure for compressive strength of horn please let me know --
I am going to shoot it a heap to be sure it is reliable but I am fairly confident it will be OK -- if anything I may increase the the thickness of the center stiffener lamination to move the bend in the limb a little further from the handle.
Graeme
Yes my conclusion is that bamboo is better in compression than the best wood but not nearly good enough for the extreme loads of short Asiatic bows. The resin I used has a compressive strength of 110 MPa which is more than twice the best wood available and the resin and glass together has a compressive strength of about 300 MPa . Unfortunately I can not work out how strong horn is as the only figure I can find is in TBB where it is said to withstand 4000 pounds per square inch but this is only 27MPa which makes no sense as this is only about half as strong as Ironbark -- if anyone has a figure for compressive strength of horn please let me know --
I am going to shoot it a heap to be sure it is reliable but I am fairly confident it will be OK -- if anything I may increase the the thickness of the center stiffener lamination to move the bend in the limb a little further from the handle.
Graeme
Graeme K
I was delighted to see this title when I logged in tonight. Congratulations on your persistance to press on ... and resulting success. The bow profile looks wonderful both drawn and undrawn. I know exactly how you feel about continuing to be challenged by this design. Your efforts with laying glass strands as 'sinew backing' have certainly paid dividends. I'm curious to know if natural fibres such as linen or hemp work in the way?
Greybeard wrote:
Like Greybeard, I believe that we have not exhausted the potential of bamboo for these bows and is still worth pursuing. Thanks to your encouraging posts, I have another asiatic build-along coming through this week and rather than pinch your thread, will start a new one when a few more stages are completed. I now have some buffalo horns waiting to be cut into strips to use on the belly ... I really hope it lives up to expectations.
I was delighted to see this title when I logged in tonight. Congratulations on your persistance to press on ... and resulting success. The bow profile looks wonderful both drawn and undrawn. I know exactly how you feel about continuing to be challenged by this design. Your efforts with laying glass strands as 'sinew backing' have certainly paid dividends. I'm curious to know if natural fibres such as linen or hemp work in the way?
Greybeard wrote:
The bow looks good and hopefully it will be a good shooter. The alternative backing to bamboo would appear to be the answer as I believe we have been trying to push bamboo past its physical limits. Having said that I will give bamboo another try as I have got it to work successfully on two previous attempts.
Like Greybeard, I believe that we have not exhausted the potential of bamboo for these bows and is still worth pursuing. Thanks to your encouraging posts, I have another asiatic build-along coming through this week and rather than pinch your thread, will start a new one when a few more stages are completed. I now have some buffalo horns waiting to be cut into strips to use on the belly ... I really hope it lives up to expectations.
Hi Archangel
Yes I am sure you can make Raw Bamboo work in compression on a horse bow it is just a matter of how short and how recurved you make the bow or in other words how much you stress the material and by default how high in performance the bow is.
The idea of using natural material in place of the glass is possible on the back where the fibres are in tension and the best material should be linen as this has the highest tensile strength and this would work in epoxy but I think sinew is probably better as it has high stretch which can store more energy but you need to use animal glue
On the belly in compression none of the natural fibers will work as they do not have compressive strength and this is why horn was traditionally used.
Looking forward to your next build -- will be interesting to see how you go with the horn.
Graeme
Yes I am sure you can make Raw Bamboo work in compression on a horse bow it is just a matter of how short and how recurved you make the bow or in other words how much you stress the material and by default how high in performance the bow is.
The idea of using natural material in place of the glass is possible on the back where the fibres are in tension and the best material should be linen as this has the highest tensile strength and this would work in epoxy but I think sinew is probably better as it has high stretch which can store more energy but you need to use animal glue
On the belly in compression none of the natural fibers will work as they do not have compressive strength and this is why horn was traditionally used.
Looking forward to your next build -- will be interesting to see how you go with the horn.
Graeme
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Stickbow Hunter
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Graeme K wrote:
I was really keen to try some raw sinew and ordered these cattle leg tendons from our butchery at school during the week. Unfortunately they are far too short and had too much meat/fat on them to be much use. Maybe the wrong cut, or perhaps domestic tendons are unsuitable? My dog didn't care however .. she picked up some tasty chew-treats this week! A friend has a large group of emus and he has indicated may cull one if it was useful. Now this sounds like an interesting possibility.I think sinew is probably better as it has high stretch which can store more energy but you need to use animal glue
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Stickbow Hunter
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Graeme K asked:
This excerpt from History's Curve may help. It's the story of how Lukas Novotny builds his asian composite bows:
Unfortunately I can not work out how strong horn is as the only figure I can find is in TBB where it is said to withstand 4000 pounds per square inch but this is only 27MPa which makes no sense as this is only about half as strong as Ironbark -- if anyone has a figure for compressive strength of horn please let me know --
This excerpt from History's Curve may help. It's the story of how Lukas Novotny builds his asian composite bows:
I couldn't find a conversion table to obtain Mpa from kg/cm but this should not be too difficult. The link to the whole article is http://www.saudiaramcoworld.com/issue/2 ... .curve.htmJust as each of these tissues plays a different role in the workings of the body, each of the bow’s elements has a similarly specific function. "The sinew takes the tension," Novotny explains. "The horn on the belly takes the compression, and in the middle, the wood takes the shear stress. It’s a simple premise, but if you don’t get the details right," he warns, "you’ll have problems." After all, when drawn, the bending portions of the bow bear some 175 kilograms of pressure per square centimeter (2400 lb/sq in). If the belly cannot stand the compression, it buckles, and if the back of the bow cannot bear the stretch, it pulls apart.
Hi Archangel
The Emu thing will probably work -- I know that they use Ostrich tendons.
Cows have very short legs for a big animal but I believe back strap tendon from cows is good. I think the easiest thing to get locally would be leg tendons from horses that you could get from the knackery but the stuff I have read and seen on video suggests that it is heaps easier to prepare back strap sinew because there is no pounding needed to break it up into fibers.
Graeme
The Emu thing will probably work -- I know that they use Ostrich tendons.
Cows have very short legs for a big animal but I believe back strap tendon from cows is good. I think the easiest thing to get locally would be leg tendons from horses that you could get from the knackery but the stuff I have read and seen on video suggests that it is heaps easier to prepare back strap sinew because there is no pounding needed to break it up into fibers.
Graeme
Hi Archangel
The 175 kilograms per centimeter square is 17 MPa which is a bit more than half the other figure I got but it does not make much sense since the timber books I have give figures as 50MPa for OZ hard woods so the horn should be higher than that. Who knows which is wrong or if the figures are not compare able for some reason.
Graeme
The 175 kilograms per centimeter square is 17 MPa which is a bit more than half the other figure I got but it does not make much sense since the timber books I have give figures as 50MPa for OZ hard woods so the horn should be higher than that. Who knows which is wrong or if the figures are not compare able for some reason.
Graeme
Hi Graeme K and Archangel,
The main problem that I have experienced is that the backing bamboo has failed, not the belly. I believe that part of the problem is the small diameter poles that I have been able to purchase. Possibly larger poles for the backing (lower crown) and smaller on the belly for compression. Who knows, just keep trying.
Archangel, I am currently persuing hemp/jute fibre that the plasterers and plumbers used before the turn of the century.
The interchange of ideas and efforts has been insperational and hopefully, together we can come up with a solution.
Daryl.
The main problem that I have experienced is that the backing bamboo has failed, not the belly. I believe that part of the problem is the small diameter poles that I have been able to purchase. Possibly larger poles for the backing (lower crown) and smaller on the belly for compression. Who knows, just keep trying.
Archangel, I am currently persuing hemp/jute fibre that the plasterers and plumbers used before the turn of the century.
The interchange of ideas and efforts has been insperational and hopefully, together we can come up with a solution.
Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
For a good bow twice paid for, is better than an ill bow once broken. [Ascham]
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]
I am old enough to make my own decisions....Just not young enough to remember what I decided!....
Hi Daryl
Sorry to have missed you at the Gathering -- was tempted to come up despite the rain but it looked like it was not just wet but potentially dangerous. Probably be up through Bris before October so we will call i and see you.
I think what happens with the bamboo is that when loaded beyond the failure point in compression it collapses the cells and gets shorter -- these cells are those which surround the power fibers so the power fibers hold the bamboo from cracking or falling apart which gives you a sort of non visible failure.
When this happens (compression failure) it drastically increases the load on the tension side because it is now wrapped around a shorter surface. The tension side which was probably near its limit anyway gets to failure point but in tension the type of failure is different as the power fibers let go causing splitting and a visible failure.
Graeme
Sorry to have missed you at the Gathering -- was tempted to come up despite the rain but it looked like it was not just wet but potentially dangerous. Probably be up through Bris before October so we will call i and see you.
I think what happens with the bamboo is that when loaded beyond the failure point in compression it collapses the cells and gets shorter -- these cells are those which surround the power fibers so the power fibers hold the bamboo from cracking or falling apart which gives you a sort of non visible failure.
When this happens (compression failure) it drastically increases the load on the tension side because it is now wrapped around a shorter surface. The tension side which was probably near its limit anyway gets to failure point but in tension the type of failure is different as the power fibers let go causing splitting and a visible failure.
Graeme
Thanks Mayland
I am a bit hooked on them -- I really like the way they shoot -- I will probably try a few different styles now I have a construction technique that seems to work but my guess is that the design I have started with will probably be the fastest pound for pound as it will have the lowest limb mass without siyahs. But it will be interesting to see -- they must have made them like they did for some reason.
Gtraeme
I am a bit hooked on them -- I really like the way they shoot -- I will probably try a few different styles now I have a construction technique that seems to work but my guess is that the design I have started with will probably be the fastest pound for pound as it will have the lowest limb mass without siyahs. But it will be interesting to see -- they must have made them like they did for some reason.
Gtraeme
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John Allan
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G'day GraemeGraeme K wrote:... I will probably try a few different styles now I have a construction technique that seems to work but my guess is that the design I have started with will probably be the fastest pound for pound as it will have the lowest limb mass without siyahs. ....
you might be interested in www.atarn.org and the link to the discussion forum there if you are not already aware of it.
If you are interested in new designs....
www.krackow.com
www.grozerarchery.com
www.horsebows.com
http://felszerelesek.lovasijaszat.hu/fe ... ek/?lang=2
Great to see another horsebow fan.
Happy shooting
They'll never hit us from this dist....
Hi all,
I got to this post late because I was tillering a couple of longbows that are half done last night.
A great looking bow, by any standard anyone wishes to apply!
1 kg/cm2 = 0.0980665 Mpa
I have a really good shareware programme that converts between just about any imaginable combinations of units. If any one would like a copy email or PM me and I'll email it to you. It is not a large programme - just one small exe file. I have found this programme to be one of the most used programmes on my computer.
I got to this post late because I was tillering a couple of longbows that are half done last night.
A great looking bow, by any standard anyone wishes to apply!
1 kg/cm2 = 0.0980665 Mpa
I have a really good shareware programme that converts between just about any imaginable combinations of units. If any one would like a copy email or PM me and I'll email it to you. It is not a large programme - just one small exe file. I have found this programme to be one of the most used programmes on my computer.
Hi Mayland
Thanks for the links -- I will go through them and see what I can find.--
I am interested in the reasons that you have chosen the particular style of bow that you use. Obviously you have been a fan for some time and have ordered bows from OS so you may have insights into the different advantages and disadvantages. Any opinions you have would be appreciated.
Graeme
Thanks for the links -- I will go through them and see what I can find.--
I am interested in the reasons that you have chosen the particular style of bow that you use. Obviously you have been a fan for some time and have ordered bows from OS so you may have insights into the different advantages and disadvantages. Any opinions you have would be appreciated.
Graeme
Hi John
Good to hear from you -- You should definitely get your priorities right and do something about work if it is interfering with your bow making.
You know what they say -- Work is the curse of the drinking man !
But seriously you should do the horse bow thing again -- I need people to compare notes with. ---- Graeme
StevenJ --- thanks for your kind words. I have had a conversion program similar to what you mention on my machine in the past but I usually use an on line site called onlineconversions.com which seems to be able to convert just about everything. --- Graeme
Good to hear from you -- You should definitely get your priorities right and do something about work if it is interfering with your bow making.
You know what they say -- Work is the curse of the drinking man !
But seriously you should do the horse bow thing again -- I need people to compare notes with. ---- Graeme
StevenJ --- thanks for your kind words. I have had a conversion program similar to what you mention on my machine in the past but I usually use an on line site called onlineconversions.com which seems to be able to convert just about everything. --- Graeme
G'day GraemeGraeme K wrote:Hi Mayland...I am interested in the reasons that you have chosen the particular style of bow that you use. Obviously you have been a fan for some time and have ordered bows from OS so you may have insights into the different advantages and disadvantages. Any opinions you have would be appreciated. ...
I appreciate the lines and craftsmenship that goes into making a full composite bow. I am amazed as to how the different materials are combined together to produce such a work of "martial" art.
As to knowing the relative advantages and disadvantages over other types of bows? I've not done that in depth review. In my own mind it produces a highly maneuverable and effective weapon. The combination of the different materials and the "C" shape meant that when strung, the bow could store more potential energy prior to being drawn than a longbow. I think I read somewhere that horn is one of the most efficient materials for storing energy under compression.
This gives a very succinct explanation:
http://www.saudiaramcoworld.com/issue/2 ... .curve.htm
http://www.ecocomposite.org/agfibers/sinewbow.htm
Hope this helps...
Happy shooting and interesting question
They'll never hit us from this dist....
Hi Mayland
I agree with all you say about horse bows and my initial interest was to get the the lightest bow with the highest arrow speed for my wife ( she refuses to lift weights and I am not sure I want her to be stronger than me anyway ). I guess I did not ask the question clearly but what I was trying to ask was why you prefer the style of horse bow you use over other styles of horse bow -- sort of why is Korean better than Turkish. I realize you may not have tried that many different types but if you have any preferences I would be interested as I am trying to decide which shape to try next. ---- Graeme
I agree with all you say about horse bows and my initial interest was to get the the lightest bow with the highest arrow speed for my wife ( she refuses to lift weights and I am not sure I want her to be stronger than me anyway ). I guess I did not ask the question clearly but what I was trying to ask was why you prefer the style of horse bow you use over other styles of horse bow -- sort of why is Korean better than Turkish. I realize you may not have tried that many different types but if you have any preferences I would be interested as I am trying to decide which shape to try next. ---- Graeme
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longbow steve
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A quick word on horn and sinew:
Horn may indeed have a lower compression strength than wood, but it is styill much better for use on short, long draw bows.
Why? Because it bends further before failing. Now you might be thinking 'how does that work?' Well, horn is not as stiff as wood for the same thickness (the high-end woods anyway) which means it is easier to bend than a bit of wood the same size. This, as well as a couple of other factors, means that the horn can bend a lot further than wood without taking a set. This, and not the compression strength on its own, is what makes horn favorabloe for these tasks.
The surfaces on a very short bow are stretched and compressed a lot during a full draw. Composite bowyers claim to be able to see the horn compressing as they draw their bows!
So, why is fibreglass a good alternative? Fibreglass, especially in a resin, is usually more stiff and has a higher compression strength than timber, and thus horn. But because its so strong, it can be a lot thinner for the same strength. Being thinner, the fibreglasds is now able to bend farther before taking a set or failing, which is why fibreglass is used.
Does that help?
Keep up the bowyering guys...
Dave
Horn may indeed have a lower compression strength than wood, but it is styill much better for use on short, long draw bows.
Why? Because it bends further before failing. Now you might be thinking 'how does that work?' Well, horn is not as stiff as wood for the same thickness (the high-end woods anyway) which means it is easier to bend than a bit of wood the same size. This, as well as a couple of other factors, means that the horn can bend a lot further than wood without taking a set. This, and not the compression strength on its own, is what makes horn favorabloe for these tasks.
The surfaces on a very short bow are stretched and compressed a lot during a full draw. Composite bowyers claim to be able to see the horn compressing as they draw their bows!
So, why is fibreglass a good alternative? Fibreglass, especially in a resin, is usually more stiff and has a higher compression strength than timber, and thus horn. But because its so strong, it can be a lot thinner for the same strength. Being thinner, the fibreglasds is now able to bend farther before taking a set or failing, which is why fibreglass is used.
Does that help?
Keep up the bowyering guys...
Dave
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Bow making courses, knife making courses, armour making courses and more:
http://www.tharwavalleyforge.com/
Articles to start making bows:
http://www.tharwavalleyforge.com/index. ... /tutorials