Crab Bow Project

Thanks for sharing! This will be very interesting :)

For sure, Kviljo!

The bending sections are only 13 cm long each...

JJ

Please keep us updated.

That's great!

13cm is really short. I thought that a part of the ear splice and the grip splice sections is supposed to bend too. Do you plan to leave the ear splice stiff?

Daniel

Daniel, you?re right, the "eyes" of the splices will bend somewhat. But the bend will not extend more than one or two cm into the splice. Notice the prominent ridges on the main part of the ears, they will prevent bending.

http://atarn.net/phpBB2/files/indian_bows_205.jpg


JJ

Yes, I see. Do you plan on adding reflex when glueing the horn?

Also, nice set-up with the four vises.

Daniel

Well JJ, sorry, but i must say again - another " hello boys i glued new hornbow " ! From mi point of view- bad wood in bend part, bad wood in siahs part, short bending part...
I like your work especialy your entusiasm , but you lost much energy and working hours for bad result now.

Why ?

Dusan, there are more people enjoying these workshop-photos, than there are people enjoying such negative comments. I, for one, will learn much more from such build-alongs than from such unbacked statements like "this and that is bad". How about contributing in a positive and productive way?

Keep it up, JJ!

Looking at the picture you refered to, the bow at the top seems to have taken string follow along most of the "inner" limbs. Doesn't that mean that most of the inner limbs should bend pretty evenly from grip to the siyah angle?

Again , Kviljo. I think that mi posts are positive not negative. :) Ther where you see negativism and no-constructiveness i see quick help for craftsman. You say , that you learn more from bad example. I understand , if its your work , and you learn from your experience. But i dont unerstand what is useful on a bad build -along .

These build-alongs where meaningful 5 years ago in Atarnet or maybe 1-2 years in( for example) -Paleoplanet or so , but not today and not here.

I understand your approach only if there mistakes make you happy. (Its joke :oops: )

Maybe it's a language-issue that makes me read your message as negative. If so, my apologies. But I believe this place is for learning from eachother - and buildalongs are a very good way of learning from eachothers experiences. One should take it for what it is, and if someone (you, perhaps) should claim that they will show the perfect replica, it should be judged as that, but untill then, I feel that we should encourage the building of bows and the sharing of the process. If nothing else, as for my "buildalongs", you will see what the materials will not tolerate :wink:

Okay, enough off-topic from me. Sorry.

Keep calm, fellows...

What I like about Dusan is that he is our bad conscience;-) He always reminds us how we can be more authentic, use the right materials, techniques and so on;-) He is a little devil :lol:

But, as always, there are people that have other opinions about certain materials and techniques. We don?t have all to agree to each other;-)

We are all here to learn (except of course the handful of master horn bowyers, who are here to give us their generous advice). And any posting of a not so perfect bow in this great place can yield some very useful information on how to improve one?s bow...

We don?t really know which kind of woods were used in Indian Crab bows. Judging from some Indian bows I have seen delaminated, I would say that sometimes incredible bad looking wood was used that I wouldn?t dare to use in a hornbow. But it was used anyway. Besides of that my experience in wooden bow making says that Hickory is a very good bow wood. Of course there are differences in quality, but that affects every wood type.

JJ

Kviljo,

regarding the bending section of Crab bows, there might be differences, as the bows depicted in the link I posted above show. The bows nr. 1 and 3 might bend longer along the limbs than bow nr. 4.

This last one, like an original Crab bow that I have momentarily here in my workshop, very clearly becomes thicker from the beginning of the siyah splice outwards, and the bow I have here even gets wider in it?s outer limbs. So it?s obvious that it won?t bend at all after the kasan eye.

The grip splice of the original bow I have here also thickens right after the eye of the splice, and the thinner, therefore bending part of that bow?s limbs is exacty 13 cm long.

Other Crab bows seem to be otherwise constructed, but at least some really have that very short bending part. I?m very curious how a replica will behave and shoot;.)

JJ

:)T hank you JJ . You are friendly , and i hope you understand me. I dont try nobody insult or so. I understand that yours craftsman soal desire show what you doing, but i still fight vith yours position boys- DONT WORK vith no good materials . And you know beforehand that this material is no "that" !

I am writing about , this , because i have personal experienc vith many broken, delaminate , no "good " woods , gleus experiments. All this i hope is past. I think that nobody from us havent many time and horns doing "old mistakes" . This mistakes have samreason 4-5 years ago - but not now boys. Its mi very hard position. There is no time doing old mistakes.

Atarn assemble very useful information . Adams book is more than "dream" for novices. I dont unerstand why not for experiance craftsmans?!?

I will try define most important fakts about "COLAGEN BOWS" (hornbow is old no right definition - :lol: ):

- best woods for bow was porous white wood vith good flexibility and good SG , but NO HEAVY (i mean waight) wood - or bamboo.Another important character is good glue sack. This characteristic have for example - maple.

- best glue is mix (today we dont know...) sinew x palate (sturgeon ) glue or Korean method fpure fish-croacker glue). Pure sinew glue is probably second choice and Hide glue is last variation.

-best usefull horns are from Water Buffalo from not very hot climate Asian area. Inner curve is recomendit.If sombody try historical correct mongol or skitian bows Himalayan capricorn is for that. Maybe sombody have good experience vith longhorn cow horns but many source(and mi too ) say that this material is worst.

- best sinew is from mix - cow backstripe sinew , longest "achyles" sinew x wild deer sinew. Pure cow sinew is second choise - but Koreans masters prefer this variation.Pure wild deer sinew ? I havent personal experisnces. Adam Karpovitz use sinew from Wild Moose. Maybe super choice (?)

- siahs best wood was from strong wood-like mulberry, acacia or so , but VERY importatnt fakt , who was tipical for all this 3 materials is WEIGHT !!! Vith this are close all another measurments - how long, thick or wide you can construct your bow .

THE KEY IS - MAKE YOUR BOW VITH SHORTEST, AND LIGHTER MATERIAL HOW YOU CAN ONLY DO IT ! BUT DONT FORGET ABOUT FORTRESS AND STABILITY !!!

This is very shortly . I dont understand what from this is so hard to understand for you guys ? This all stay on old masters experiences and mi stupid experiments for this 10 years say same.

Why you mean that you "open new gate " ? This old guys work abou 2000 years.

Thats mi position and from this reason iam writing so "negativ" words. Go and do best for you !Not "midle" quality. We see "hornbows " like this 5 years ago. Its enough.



:lol:

I think this would be kind of like me telling you not to post on here until you have mastered English as perfectly as your other friendly European neighbors have done. After all, the technology to learn that is out there and you insist on posting in a crude prototype version....

:oops: Patrick ,you are right. Mi apologise... Mi English is stupid. :roll:

Maybe Dusan does not mean to be negative.......it does seem to come across that way though....


Regardless of what anybody says, Im happy to be able to follow along with this build along because JJ is far more advanced than I........and it is a pleasure to look at anothers work.

Please keep the pics coming JJ.

JJ,
I have only examined one cut up crab bow and the core of the siyah was almost flat on the back with a ridge of 1 to 2 mm high. It reaches its thickest point opposite where the string knot rests.

However, I think that some of the better quality bows were made like yours, using wood in the core to stiffen the siyahs rather than just build up a sinew ridge as was done in the bow section I looked at.

I checked the bending section on one of my crab bows and it was 320 mm. I think some of the others are shorter. If they follow the same splice placement as the one I saw in pieces and as the one you are making, then the whole of the bending limb including the splices bends though not uniformly to the same degree.

I will be making cross sectional drawings soon to match the dimensions I posted. I hope they will be useful.

Hello Bede,

I will make a photograph of the bows limb that I have here. It looks the same as bow nr.4 on this image:



These bend quite clearly only on very short way.

JJ

[external image]

Bede, here also the back remains flat until the knee of the siyah. But it is apparent that only the ca. 1,2 cm thick middle limb part can bend, the outer part can?t bend at all, because it?s thicker and wider. The near grip section is also too thick for bending. In this bow, including the "eyes" of the splices, the bending part seems not to have been longer than 15-16 cm.

I think there are different types of "Crab bows" (or different qualities). I imagine that the extremely short, strongly stressed bending section which should store a great amount of energy, combined with a very stiff outer lever arm, is the essence of the Crab bow design.

JJ

I forgot to add, this original is 132 cm NTN and has a mass of 585 grams. It appears to have been a very strong bow.

JJ

JJ; I agree with your assessment. Anyone who examines crab bows closely will see that they are none inferior than Turk.

It has been mentionend that the horn is rather thin. The bow above has a thickness of 13mm. So what is thickness of the horn? The limb could be made by a 5mm core, 5mm horn and 3mm of sinew and that sounds like normal measurements.

Daniel

Daniel, I guess sinew forms the thickest part. Horn and wood seem very thin on originals. I saw a delaminated Indian Bow (not a Crab bow) that had nearly paperthin horn and wood, but lots of sinew. The sinew had turned to fibers again, so it was not possible to determine its thickness, but it must have been a massive layer.

JJ

Based on the bow I saw, the wood and the horn are both thin. The horn is one half the width of the core. The horn entirely fades out before the limb to siyah junction. There is a considerable amount of sinew on the belly. At the knee, where the great bend is, the belly sinew is close to the thickness of the core.

The illustrations from Stone's Glossary... show one bow braced and the others unbraced. To get a real idea of how they bend you need to see a drawn bow and, outside of art, the only ones you can see are reconstructions.

I believe that there were two qualities of crab bow, one with more wood in the core and several slats of horn that went up to or past the knee and another as I saw dissected with minimal horn, a small amount of wood and a lot of sinew. However, I have only direct evidence of the last form.

I have four crab bows which are all too old to brace, but I can flex the limbs a little. The limbs do not bend uniformly. They flex more in the thinner parts. There is no perceptible flex within 50 mm of either the knee or the grip junction, but considering the likely construction I would expect a small deformation there at full draw. This is because the sinew on the belly side would have little compressive strength.

When JJ has finished his reconstruction, it will be instructive to see how it bends. That is part of the experimental nature of what we are doing. Lucas Novotny had made several of these bows that performed well the last time I checked. Jaap Koppedrayer and he had examined the cut up bow I have seen, though I think it was after some of the bows were made. Every time someone makes one of these bows we learn something new.

One thing more to emphasise: the bows were highly reflexed in construction. Two of my bows have the tips almost touching and the other has them overlapping. There is some indication from the nocks that they had been strung in their past life so this is the residual reflex. The bows you see fully opened out as in the top one in the Stone illustration may have been strung for years in a museum or it is a bow with minimal wood and horn that has followed the string. This is another area where I think JJ is right. There have to be different qualities of bows. In some the reflex may have been meant to reduce for ease of shooting. As well as warriors, women, children and old men used bows in India.

I wouldn't want to make a bow with a known inferior construction. I'd rather go for a quality crab bow without too much sinew on the belly.

I also noticed something else that may indicate different constructions. In the picture above, bow 3 looks like it has a reflexed grip, while 4 does not. There is also a picture of a crab bow with high grip reflex in Adam's book.
There must be a very broad range of possible draw weights depending on the ratios of horn, wood and sinew and the type of reflex (grip, glued in or formed by sinew).

I made a bow with a reflexed grip and an average horn/wood/sinew cross-section of 12mm thickness and it turned out heavy. I had to scrape quite some horn of to reduce the draw weight because I didn't trust the 70g of sinew in the backing would withstand a high poundage.
If I made a bow with less wood/horn and a similar amount reflex that is gained by a larger amount of sinew instead of a reflexed grip, the draw weight will probably be much lower.

Daniel

Bede, is it correct that the horn of the dissected bow is half as wide as the main core? Then I would suppose it to be a kind of "fake bow", because making the core wider than the horn makes no sense to me, but in a finished bow it could not be seen by the buyer... I?m guessing that the good quality bows did have horn as wide as the core itself and that there was no sinew parallel on the belly, because this also can only be interpreted as some fake to pretend a better, fully horn-coated bow. The only "non-fake" reason that I can think of for putting sinew on the belly is to hold together a belly made of several narrow horn strips.

What about the x-rays you spoke of in your thread, Bede ;-)

I don?t think that I will put sinew on the belly in the reconstruction, as I don?t want to spoil the bow... I want the best quality I?m able to get.

JJ

Might the sinew on the belly be there as a security against string breakage? These bows have pretty massive siyahs, so they should be extra sensitive to it.

Daniel,
When I saw the cut up crab bow, I asked several people about crab bows they had examined. Edward McEwen told me that he had examined many crab bows as well as building them. The belly had a curved cross section and the horn was on the highest part of the arc. It was the only part affected by compression. The bowyers were manipulating the neutral plane of the the limb. The part of the wooden core projection beyond the horn was very thin and like the rest of the belly it was encased in sinew. It was not overstressed while in contrast the horn was fully worked by the compressive force.

As far as I know all crab bows were covered in sinew on the belly. Adam in an article commented the sinew was laid on parallel to the axis of the bow. The cut up bow I saw was similar. Even so there would be lateral strength in the sinew layer. What this means I can explain by analogy. If you hold up the unserved part of a bowstring, it just flops down because it has no stiffness. If you hold the served centre section, that part stands up like a stick because the compression of the string changes the nature of the structure. Indian bowyers were taking advantage of this when they reduced the horn component. Persian bows, which are also covered by sinew, have multiple horn strips. So do some crab bows. Perhaps the bowyers discovered that a technique they used to cover the horn strips made a difference to the way the bow performed.

Regarding the setback in the grip, I think that in some bows it disappeared when the bow was strung if the grip/limb junction was not stiffer than the grip in proportion. I know of this happening in some reconstructions. In some bows the grip was spliced into the limbs, while in others it was applied to the back of the core strips.

I think that you should make your bows as you think best. Then when you have a working bow, experiment with the variations known from historical examples. The bowyer knows the limitations of his materials. Saying that this or that technique was used historically is only stating a goal. If the horn is not right or your piece of wood is not bending the same way as another are examples of where your environment determines your choice.

Bede,

when the sinew is laid parallel, the lateral modulus of the material is probably the same as the one of pure glue. It might a bit higher if there is a stronger bond between the fibres and the glue, but I don't know the chemistry to be sure. Since the modulus of the horn and wood is higher I don't think there will be a pronounced wrapping effect.
I can't think of any advantage that sinew has over horn, except for the high breaking strain in tension, which is only needed on the back. The stiff to weight ratio is certainly not a benefit for the bow. Kviljo's suggestion is actually a possible explanation, but it could still be done with a whole-width horn.

Thinning the wood on the sides makes sense within this construction, which as a whole does not seem to.

In the whole bow, there is still the physical weight per draw weight, the stringfollow and the dynamics to consider, so maybe there will be a positive effect revealed when bows are made and compared.

Daniel

Daniel,
I would be interested to see some tests of lateral strength of sinew layers. considering the strength of the glue is great enough to hold the bow together, it by itself would be enough to have a noticeable effect. However, when you consider the separate bundles of sinew in the layers are only held together by lateral gripping between their overlapping parts, The strength must be considerable.

Part of the Poisson effect on wide limb composite bows might also be a result of the shrinking of the sinew on the back too. Plumped up with water or liquid glue, the bundles of sinew would shrink laterally as well as longitudinally as they dried.

A complete wrapping of the bow in sinew puts the whole of the bow in compression in the same way that the heartwood of a tree is put in compression by the sapwood. In a tree this contributes to the stiffness of the trunk, a fact taken into account by shipbuilders making masts for sailing ships in the old days. I was surprised by Adam's comment in his article about a crab bow in the JSA-A that the sinew on the belly was longitudinal rather than circumferential. I thought the winding of the sinew around the limb would have been necessary to get any benefit. But I cannot argue with the artefacts. The bow Adam investigated and the one I saw have similar construction. Maybe bowyers discovered that the longitudinal sinew was enough for their purposes and it would have been easier to apply.

However, I believe the thick sinew on the belly of the knee of the bow was not a good design choice. In a sense, it is a dishonest method of construction. It pretends to be something it is not. That is how I see it now. Someone might build a bow like this and find there is some advantage and I will have to change my opinion.

Having sinew on the belly to prevent damage if the bowstring breaks is unlikely. I have had altogether too much experience of bowstrings breaking on highly reflexed composite bows. This comes from using linen strings in the Utah desert. The low humidity (16%) weakened linen strings that had been perfectly OK in higher humidity environments. If the ancients made their bows as well as Adam Karpowicz, then the bows were reasonably safe in string breaking incidents.

Crab bows often had gut-cored silk wrapped bowstrings. My experience with gut strings suggests that breaking is an unlikely event. They are extremely tough. The arrow nocks suggest that crab bow strings were often 4 to 4.5 mm in diameter. These are strong strings. The gut string I have been using on my 80 pound Turkish bow is less than 3 mm thick and is showing no strain at all. I am shooting light weight arrows that would not be efficient in taking energy out of the bow so the string has to be able to take a lot of force.

Good point on the strength between bundles. I have access to material testing machines for tensile and compression tests. Wednesday is a holiday, hopefully I'll have time to prepare glue and glue/sinew specimens for testing (after further work on the cores).

Regarding the strings, that's interesting. Does it compare to fast flight in stiffness? Just curious because of the tip breakage problems reported by Adam.

Daniel

Nice build along. Thanks for showing!

Hello Daniel, Bede, it is clear that a sinew layer shrinks laterally, too. But I see no benefit in having it on the belly. The forces of sinew layers on back and belly tend to tear the materials on the edge away from each other, which of course is not desirable in a sandwiched construction... Longitudinally the force of a belly sinew backing is also acting against the reflex that has been built up on the back! This way the reflex of a bow and it?s cast would be weakened...

When I use a narrow horn strip on a widebellied bow, I can cut off the excess wood on the sides, too, and the bow would act the same, but without the mass of the side ridges! A thicker sinew layer on the narrower back would compensate for the loss of side sinew.

But the bow would lose it?s sideways stability. The wider limbs of the original crab bows are stiffer laterally. However, it?s a strange construction...

Maybe Adam Karpowicz could join into the discussion?

What about Lukas Novotny? He has maybe the greatest experience in making Crab bows today.

This is fascinating stuff;-)

JJ

I don?t remember, was the paint always laid directly on the sinew? JJ

Sinew on the belly might keep the lateral shrink in control. I have bow were the shirk has pull the horn belly in latitudinal cracks.
I have made bow with narrow horn strip and sinew at the side on belly, it was the fastest bow ever :)
I have made bow with two horns strips and the shrink pull them apart and rounded the belly.
But paper thin horn I have never try.

I believe the thick sinew on the bellies and especially so on the sal/kasan bend helps to keep the bow together. I now think the sinew at the bend could be applied diagonally for a better effect.

The glue lines in the extreme bend are under a lot of stress, which tends to cause delamination. When the joining surfaces are deep in the limb, encased in the glue/sinew mix, the glue lines are closer to the neutral axis of the limb. And the modulus of glue is very similar to horn. As long as the glue stays intact with no cracks and dry, it acts essentially as horn itself. The difference may be the resiliency (presumably greater for horn) and the rapid loss of stiffness for glue in high humidity. It does not mean the glue could be used in place of horn in sal where the bow flexes, since its breaking strain is less than horn, but it will do in the less stressed, non-bending areas of the bow.

The bowyers seem to use sinew and glue as a "bulking" material in these bows. When I poked with a needle into the grip sinew, I found what seem to look like glue-soaked fabric. I think we should be careful to criticize the bowyers though. As I said before, I do not believe the ancients were as conscious of the bows' efficiency and arrow speed as we are now, if at all.

The crab bows I have seen all had paint directly on the glue/sinew surface.

Adam

" I think we should be careful to criticize the bowyers though. "

Amen. Thats what i try (with mi stupid anglish ) say.

If the sinew on the edges were on the back side of the neutral plane, it would concentrate the compression closer to the middle of the horn laminate, or in other words it would put sideways pressure on the horn, and by that making it possible to use a horn that is narrower than the core and back sinew? This effect might also be useful for bows with several horns along the limbs.

I don't think the analogy with the string works, because the longitudinal stiffness of the materials are reversed. While the string have no compressional strength, the serving does. And in the bow, the limb is much stiffer than the "serving" of the sinew.

I could easily believe that the bowyers were not as interested in efficiency as we are today. After all these bows were a much more common commodity made to make a living than it is today. If tradition tells you what the bow should look like when it is finished (important if you want to sell the bow) and e.g. wide enough horn is hard to obtain, why not fill in with glue and sinew as long as the bow does not suffer too much. Plus, you can be pretty sure that the customer won't bring a broken bow back to you if you wrap it well in sinew - which is of considerable importance if you make bows for a living and the customers life is depending on the bow. We see this in ancient wooden bows too, where they don't have flightbow-skinny tips because you are depending on the bow much more than just when on the flightshooting range.

Composite bows were always expensive. If you made an expensive weapon that did not perform as expected and your customer survived the episode, I think you could expect a knock on the door by a very angry man with a sword.

Adam's comment about the expectations of old bowyers should be taken into account. Efficiency to them probably rated durability and ease of use as important too. With crab bows we are not looking at flight bows. They were for war or hunting.

Adam also stressed in his book that glue should be left to dry for a long time if you want durability and maximum strength (or at least that is what I understood from what he wrote). So if you are going to do tests on the sinew glue bonding, make sure that the glue has had time to cure.

My string analogy was intended to suggest that by encasing the main structure of the bow in a tension structure, which compressed it, you could increase the stiffness of the whole and possibly allow less structural support for the compressive parts of the bow.

The very edges of the limbs were mainly sinew. The breadth of the bending parts of the limbs were intended to supply stability for the long siyahs.

I have seen what appears to be metal foil between the paint and the sinew. Something Adam wrote and a few conversations with Edward McEwen suggest this was a covering that maybe protected against moisture penetrating the limb.

The sinew at the knee seems to be applied straight in the bow I saw cut up, but a diagonal wrapping could be concealed in the matrix. I have seen bows with bindings applied after manufacture at the knee and the grip junctions, but I cannot remember seeing a bow with intact paint failing there. Most damaged bows were either broken at the nock or looked like they had been bent backwards in their later life. Insect damage was sometimes noted on the belly of the bending limb or on the back of the knee portion. It looks like in the cut up bow had severe glue deterioration late in its life. The sinew had detached in parts on both sides of the knee. There were gaps in between the sinew layers in some places. Some of this may have happened when the bow was cut up.

Regarding the strings, the gut string had enough resilience to prevent any problems with the nocks. I think it was a little more stretchy than silk or linen. In manufacture, it was stretched and dried under tension. It seemed to perform the same in the 80% humidity of Georgia and the 16% humidity of Utah. In practice it seemed to come to the same brace height under all conditions. I had knotted it a bit short by mistake and the bow was a little more highly braced than normal. It vibrated like a cello string when plucked.

The idea of the sinew casing the whole works and compressing the mass makes sense. Think of airplane fabric shrinking with the application of airplane dope.

Certainly maximum cast was not the only game in town. longevity of a bow was paramount. How about a bow which could be shot in adverse weather? Of course ancients knew all about performance.

Just because we have not found flight shooting ranges in India, or Central Asia or Japan does not mean that they did not exist.

It would be premature to judge any ancient techniques without trying them out, but I suppose it is natural to speculate.

To hold a fine old crab bow, or any fine old bow is to know that its maker was a master, was trained by a master, who belonged to a "school" of bow making, who was aware of other schools, who had techniques which were sought out and prevailed. Crafts were divided into guilds with artists working in specific areas. Only the best of these masters improved their craft and the craft itself slowly crept forward.

Here we are now centuries later without teachers or masters trying to discover secrets no longer practiced or necessary. The best we can aspire to is to reproduce their work from the fragments left behind. Those fragments are our teachers, our masters and we must first learn to reproduce them in the best spirit of the originals. Before an apprentice is allowed to make any changes, he must learn to duplicate exactly. Under the circumstance this may be the best possible outcome.

:) Halelujah , Jack. Thats what i mean, is esential for Atarnet.(I hope...)

OK, Ok, I?ll put a sinew backing on the belly :D

Bede, Adam, Jack: how thick is this belly sinew supposed to be in the bending parts? In the knees it is quite thick?

One reason for putting it on the knee comes to my mind. The thicker it is, the more difficult it becomes to steambend wood. And in a Crab bow with this extreme siyah angle it?s one of the biggest problems in making this bow. So they left the wood here thinner to make steambending easier; later they gained thickness with the sinew layers. Sinew/Glue mass can be very stiff, so it adds to the stiffness of the knee. However, adding some wooden slats for thickness later would have been lighter in weight...

JJ

In the other thread, Bede said the core was 10mm thick at the knee in one bow. I measured the bending radius and angle in one of the pictures and made forms with similar radii and angles.
So far I succeeded bending a 7mm thick soaked air dried maple slat in a reasonable (I hope) angle, and also several 4 to 5mm yew slats. The 10mm maple is soaking and will be bent soon. I hope my maple will do better than JJ's.
I plan to collect curved branches in spring when the wood is wet again.

JJ, laminating thinner wood slats would be easier and better. Perhaps the bowyers had apprentices that had to pound all the sinew so they didn't really care ;)

Daniel

I like your work , Daniel. Be carefull, yew worse soaked glue than another woods.

The forum won't let me attach the file, so I'll just post a link to the picture:
http://itp.tugraz.at/~skerm/crabbows/maple_ears.jpg

I bent this 10mm maple 3 days ago after 8 days of soaking in water and took it from the form today. Before bending, I rounded the outer edges with a cabinet scraper. I cooked it for about 1 1/4 hours. As the dual form was shaped on a belt sander, the bending radius is not constant. I estimate that it varies between 35 and 45 mm.

The lower slat in the picture split slighty, you can perhaps recognize the shadow in the bend in the bad picture I took with my cell phone. It is only superficial, so nothing to worry about. I'll just glue it back on. This is the quarter sawn slat. The other one is halfway between quarter and plain sawn (from smaller diameter wood). A small splinter raised on the quarter sawn side. This may indicate that it is safer to work with plain sawn wood for this bending, but clearly two slats made with disregard for the growth don't allow definite conclusions.

Daniel

I am guessing about the exact thicknesses, but I will base it on a check of the photograph.

The back sinew is 2/8th the thickness at a point near the centre of the bending section.
The core is 4/8th.
The horn is 1/8th.
The belly sinew is 1/8th.

Soon I will have it measured more precisely, but some communication hardware problems have taken up my time.

As you can see, the back sinew is twice the thickness of the belly sinew. On the knee, the core looks 25 to 30 % thicker than it is in the bending limb. Part of that might be the small core ridge. It does suggest the bending might have been easier during construction.

Thank you, Bede. I?m surprised about the thickness of the wood. For a limb thickness of 12 mm that would correspond to:

back sinew - 3,0 mm
wood core - 6,0 mm
horn - 1,5 mm
belly sinew - 1,5 mm

JJ

JJ everything I have found out about these bows recently has surprised me. The thinness of the horn is apparently common in them.

[external image]

Got the horn strips glued on some days ago. I noticed a heavy progression of core weight... The horn which is full width and ca. 5 mm thick in the moment, accounts for about 110 grams and the glue provided more than 50 grams, but it?s weight is decreasing from drying (20 g less in 2 days). After finishing the core will of course be much lighter.

Guess that?s the reason for the narrow, thin horn on the original bows;-)

JJ

pic

:shock: attaching just worked for the first time.

This is a picture of the maple core I prepared. I made two major mistakes in the assembly.
First, when I had the ear pieces glued on, I saw that the angle was different between the two ears. Each of the ear pieces is made of two 6mm thick maple slats. I suppose the angle mishap was caused by warming for the glueing. One piece probably had a higher residual humidity from bending and went back a bit towards its original straight shape. The temperature at which the wood starts to become soft depends on the humidity. To get an even angle, I steamed both ears until the glue lines softenend and then clamped the ears in a proper position. This caused the two slats to straighten more, loosing some of this crab look. To correct, I will have to splice in another more curved piece. As a beginner I can use the splicing practice anyway. ;)

Second, I made the limbs too long, by 6cm each. There are now 17cm between the V-tips of the ear and grip splices. Maybe I'll just leave it at that and draw further.

Daniel

Daniel, how many pieces did you glue into your ears? It looks interesting! Can you give us a close-up picture?

With spliced in curved tips the crab look should be ok;-)

JJ

At the moment it's 4 pieces. In the other thread, Bede said there's only a small wooden ridge making that triangle, the rest is mostly sinew. This is why I added the yew, I will shape the ridge from these pieces.

I really need to get green birch and maple in spring to try bending thicker pieces (15mm). Then I can shape it from a nice single piece without messing around with the glue so much. As I said before, 10mm worked on soaked air-dried planned maple, maybe it'll work for 15mm with green wood when I leave a growth ring intact on the outside of the bending diameter. I'll also show a picture of the one were I used the 10mm maple when I am done.

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Finally this is the crab bow with 3 layers of sinew.

JJ

Uch JJ - again small reflex . This time in Crab bow you have max chance contact tips each other :shock: .Maybe next time... Kasan ridge looks to me so small. I think you risk move in this place when braced(?).

JJ; Very nice shape; authentic to my taste. Maybe a little more sinew on the ridges for security, as Dusan has mentioned..

Dusan, No need to overdo the reflex or the poundage on an experimental bow. It needs to last a while for testing and to get a feel for the originals.

First you walk and then you run. No need to hurry. This is a commendable bow.

:lol: experimental ,Jack ? Your subeixi bow was experimental.Thanks to Atarn and others sources we know about crabs good budget info. I can tell you from mi experisnces - its very hard dont go vith crab to the fine contact reflex :lol: 90 degrees in kasan eye area was in half way to cirkular .
Ok. no matter , i like JJs effort :D

Dusan, your observation is true: there is not much reflex in the limbs of a crab bow; what looks like a lot of reflex is in fact the steep angle of the recurved ears;-) Turkish or Korean bow limbs are much more reflexed. Indeed my crab has the siyahs not crossed, but I don?t think it would make a big difference. By the way we are still awaiting your bows ;-)

Checked the original example for the siyah ridges and I guess I?ll put on more sinew there...

Thanks, JJ

Like i say idont make mi bows for atarn pics show. I make for quality performans max clos to old days. If i dont satisfid vith, you maybe dont see looong time nothing :lol:
I show pics from mi work place and you can see that i am not a lier.I think that you - first or secont turkish or another light bows makers here was plenty. 8)

Awesome, JJ!

I've been wondering what the extra reflex near the handle comes from? It seems to be quite common in these bows? Is it perhaps a result of a thicker layer of sinew close to the handle?

Dusan; It is time to show us your bows. We are all trying to be friends here and help eachother. We can help you too. For someone who has an opinion on every other bow posted here, you should be brave and show us your work.

Most people here are understanding and kind natured so you probably won't have to worry about criticism so show us that you are not afraid and post your bows. One person's opinion is not enough. You need the help of your friends and we do want to be friends so it is well time for you to come forward.

No more excuses. We want you to participate. Be one of us.

Best wishes and most sincerely, -j-

Just thought that I would post these photos here in this discussion. It is the Crab bow that Lukas Novotny is building for me. It is almost finished , but here are two photos before the decoration was applied. Hope they are of some use to you who are building one.

strung

Kviljo, this reflex near the handles simply occured when I drew the heated limbs to a reflex before and in between courses of sinewing. I guess the fades are more flexible than I had expected.

Alan, thanks for showing the pics of the bow by Novotny. How long is the bow? Are the kasan ridges wood with little sinew? Do you have closeups of the siyahs??

JJ

I have not received the bow yet ,the lacquer from the decoration being applied is drying , Lukas says it will be ready soon. The strung length according to Lukas is 50". I will post some good photos when I get it.
Not sure about the kasan ridges.
The draw weight is 75#

The first attempt to string the bow. There are several problems: The limbs bend too much in the middle (which is easy to correct) and the angles of the knee and the Siyah end are too steep (which seems a bigger problem as the bow could become unstable). I was not able to string the bow. I think I?ll have to replace the recurved Siyah end with a straight one to have a chance to string it. I do not think it will be possible to change the angle of the knee... Does anybody have suggestions?

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Knee and Siyah angles compared to an old crab bow


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The bow on the tepeliks. They may be a little too short...


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Some minutes after relaxing the bow...


Best regards,

JJ

All I can say is wow JJ,just thinking that the bow may bee too heavy,everything looks so perfect ,It is surprising that it is not doing what it is supposed to do,I am litteraly at a loggerhead thinking how this bow could be strung and preform as I can bet anything it is going to shoot and like a bloody bullet.
Hats off to you jj you did it.

Nice work, congratulations. I brought a bow like that to brace with custom-made tepeliks (much more curved), followed with a pegboard, although a strong assisstant to bend the bow over the knees would probably do fine as well. I suspect these bows were kept strung for rather long...

Adam

Thank you very much, PJ! But it is not finished yet ;-)

Adam, thanks for your response! What is your opinion on the knee angle?

Best regards, JJ

:shock: great
(bei diesen kurven dreht sich einem ja der magen um)

It's beautiful!

What was the problem with stringing?

The curvature on the last 10cm or so towards the tip should not be a problem because the loop of string of passes on the side anyway. The curvature on the wide section necessitates a higher brace height for the string to clear the siyah. I think that helps with stability.

Daniel

JJ,
First time string bows of this shape can be really difficult. I once had a discussion with Jaap about his and Lucas's studies of crab bows and also I have spoken to Edward McEwen about his reconstruction.

From those discussions, I would follow Adam's advice. Lucas happily strings a crab bow over his leg in the UTube video, but that might be one that is either weaker than you made or that has opened out more. I have strung highly reflexed bows by the cross-legged method but there was always a lot of adjustments to do afterwards.

More curved tepeliks are a help. I have made a pair for when I am adjusting one of Adam's highly reflexed bows and it removed some of my nervousness string the bow by myself.

I would consider a shorter than optimum string for the initial bracing because it would enhance stability. Once strung you can evaluate the curves better. If the string knots are just touching the belly of the kasan rather than the core of the string running along it, I think the bow may stay stable for a while. However, I would not draw it with that string in case there were stress related problems.

Congratulations JJ,

Shape looks fit. Be careful for temp. when you use the tepelik. High temp. is very dangerous for stability ,specially very first time tillered bows.

Cem

Daniel,

the problem is the extreme bend needed to get the siyahs somehow perpendicular to the string. I guess that it could overstress the horn. I?ll have to try to open the angle of the knee a little with low heat (I?ll be cautious), but I suspect it won?t work.

Thanks, Bede and Cem! I will make some bigger more curved tepeliks after WTAF ;-).

I could distribute the bend more evenly around the limbs by scraping the horn already, this will help for sure. But near grip and near knee areas must be brought to bend even more to get that beast strung.

Lukas Novotnys? crab bows are less reflexed, maybe a little longer, and the knee angle is considerably over 90?, while on mine it is a lot sharper. A friend received his crab bow from him some weeks ago, we measured 70 lb@28", but it can be strung quite easy. The very light bow is excellent and shoots like a rocket launcher...

Cem, what are your experiences with too much heat while on the tepelik? I am very cautious with any heat since I once heated a limb too much to correct it, and the glue between horn and wood crystalized, which led to delaminating...

Best regards, JJ

Looks good JJ ! like other says-be carefull. First stringing and tilering process was very nervous - adrenalin game :lol:

JJ; A nice looking piece of work. Are the tips re-enforced with horn? They look fragile.

JJ:

Very first time tillering is very dangerous for delaminating and twisting problems. İf the heating is too much( over 50 C) snew can delaminate from core. Form of the bow is very important. I heat the bow under the sun and wait for a while till the bow warm and I use the tepelik with axis control. Bend the bow step by step and wait for a couple of hour in each step, check the axis. Do not need heat the bow in every each step. Snew backing should be overlapped the belly of the bow about 3-5mm, it prevent the bow from delaminate the snew from core.

Cem

Did you manage to string this bow? Time for an update? :wink:

I second that Kviljo!
I'm fasinated to see what happens and how it turns out.
Personally I think the more curved teplics and pegboard are the way to go.

Hello,

I managed to string the bow some weeks ago with very curved tepeliks, like proposed by Bede. It was no problem to string it, but the braced bow was highly unstable because of the too steeply angled siyah knees. A stable brace height would have been very much too high for any use of the bow... I tried to open the knees with heat but had no success... Learned a lesson, and I guess it is time to start another bow ;-) No photographs of the braced bow; I had to use all my force and attention to prevent the beast from breaking in pieces....

JJ

Two ideas how to save the bow. May not be good ones...

Hmm, this is interesting. Are you sure the steep angle at the knee is to blame? It certainly looks fairly close to the originals?

Might these bows have been braced and put in a "holding-jig" for some time, to give the bow some stringfollow, and make it less unstable?

Perhaps a thicker core or other grain orientation of the core could aid stability?

Looked like this?

jkekoni, haha, yes you made the photograph;-) It looked like this when I braced it. Somehow ridiculous....

Kviljo, yes I am sure it was the siyah angle. I tried to open it but it was too massive. I think the splice was damaged in this operation, so no further experimenting with this one. But I learned a lot. You learn more from failures than from perfect results, don?t you think?

I have begun a next one with a more open siyah angle. We?ll see...

JJ

:evil: But I learned a lot. You learn more from failures than from perfect results, don?t you think?

What i say always ..?
:lol:

This final and ridiculous shape is very close to the actual old strung shape.

The problem was that the siyahs were pointed halfway forward at a quite high brace height, so it was extremely unstable. I searched for a picture of the braced shape of a very angled Indian composite, but didn?t find any. Could you post a picture of such a bow, Jack?

I found this picture on my HD, but I am not quite sure where it came from.

Anyway, please don't hesitate to post other photos of strung bows.

I did string my first crab-project without the horn on the belly. It looked really strange to a longbow-bowyer :shock: Still, I think that has more to do with my mind having to get used to the shape, rather than the shape being odd. Getting used to the extremely high brace height is also something that my mind seems to have a hard time with, hehe. I think I figured that mine would need at least 7 inches to look well behaved.

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JJ, have you considered removing the sinew around the bend and cutting the siyahs off with a V-shaped cut? You could file the pieces for a good V-splice fit at a reduced angle and then add the sinew there again.

Daniel

:D Well boys some of crabs have same extrem angel like yours JJ. Jack was right. See from Ingo Simon coll. for ex.

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here i think artist know what doing - you can see how bow in max brace curved his arms extremly... /6-7 cen./


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Kviljo, thanks, I was thinking of that photograph but could not find it again...

Dusan, the bows you show are 90? angled in the siyah. On mine the angle is under 90, perhaps 80-85?. I think the extreme forms of the crab bows go just until the limit, I went over it ;-))

JJ

Could it be that the original bows were wrapped diagonally with sinew to gain extra stability?

:lol: yes , this is the oldest information ... Because this Crabs was wraped all. Any horn wasnt see... look more to Crab pics , Kviljo! :lol:

...I was going to say that they all were, but then I didn't want you to kick my butt for forgetting about the one that were not wrapped :P :wink:

Then the question is how much such wrapping helps in the wide-limbed bows, and how the wrapping was done? Two layers 90 degrees to eachother like in the scythian bows, or simply one transverse wrapping?

Anyway , (once we discus about if i good remember..) before lyering this diagonal sinew you must tillering that bow. After you haevnt any chance. So JJ have a problem ... 8)

There you guys go. Stones Glossary. Good book. Not expensive.

It?s not about stones, Jack... It?s about bows ;-)

I think Jack were referring to where the picture I posted came from 8)


Dusan, could one not tiller the bow - get the correct bends in the limbs, and then wrap it, and then string it? The sinew wrapping does not prohibit any heat-corrections?

:D hm , only in teoretic mean- maybe yes. If you before fantastic tilerid separatly wood core, horn - maybe . But mostly not , because you can not predicted how this component worked vith sinew layer.
Yes - you can vith heat moderate sinew , but you cant succesfull moderate horn , if he need scraping ... or sides .
I dont do it . I always first tilering and next lay new diagonal layers. Evan than i have often probles vith tillering. :cry:

This teory can fumktion only if you glued components like modern wood /polyester bows wher each layer have perfect constant thick and wide...
Grozer work i think in last generation "bio" bows vith this modern technik. He presed sinew layer - which looks like polyester layer . Than he can glued all components in form like modern bows and still be in natural clasic sinew x wood x horn composite. His new turkish bows looks very close to historic originals , but his shooting quality is questionable ? I haevnt new information - any of mi friends didnt buy this bows.
But its imposible if you worked vith genial old way .

Grozers "bio" :


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The crab bow I saw cut up had sinew applied longitudinally on the back and the belly. Most diagonal or transverse wrapping appears to be later repairs. Adam in his book writes how the varnishes they used softened the existing layers of varnish to bond. This means that later paint jobs could overlay repairs without necessarily looking out of place because of flaking.

Looking up something for another thread, I saw that Sind bows, though they are coved in sinew too, have a different internal construction. Instead of having a pair of narrow thin horn strips that are not as wide as the limbs, they have wide deep horn strips that are very convex in the centre of the bending sections. They run partway up the ridged section too at full width though they are thinner. The sinew on the belly is not as thick as on a crab bow.

I have a crabbow that I have 2 layers of sinew on right now and will be applying a third layer soon as I procure some sinew.I did not put any sinew on the belly and I am wondering how much sinew I should put on the kasan eye and the ridge?any suggestions?

Dusan , some info about the new Grozer biocomposit bows.

They are a normal wood glass laminate with a sinew-horn top surface. The newest ones this horn surface is changed for something else. Looking like old eye glasses frame. I've shoot with the horn belly version and it working prety well. My friend tested it and it holds under extreme use too. (flight)

The bows are good to shoot, low resonance, may a bit faster then the normal version. The fastest is the Assyrian.

Thank you Fusizoli. Nobody from mi friends havent any experisnces vith this new variation. Hm... i thing its pure bio.
Anyway new look closer to old disain.

Interesting info, Fusizoli. Is it really confirmed that they have a glass fiber "core"?

I think there was a discussion on the longitudinal sinew on the belly here some time ago, but I don't think there was any conclusion on the matter. It would be interesting to know if this was a common constructional feature. Maybe it simply is a "bulking material" as suggested easlier, and the longitudinal configuration gave the best compressional strength? I came across a section in Adams book, where it said the sal was covered longitudinally, while the kasan was wrapped diagonally.

As PjSingh I too would be interested in knowing how much sinew the kasan consisted of. I guess at least some of the ridge must consist of wood.

I will be studying one or two original crab bows in March/April. I'll write a report.

PJ,
This depends on how authentic you wish to be. The dissected bow I saw had the splice between the core of the gosha and the core of the bending section of the bow nearer the grip than the "kasan eye". The sinew on both sides of the core at the end of the ridge was the same thickness. The core and the back sinew and the belly sinew were almost the same thickness each. As the horn on the belly became thicker towards the grip, the belly sinew became proportionally thinner.

This was only one bow. Balfour's dissection showed the sinew as thick on either side of the horn strip on the belly as it was on the back. This could mean it was similar to the bow I saw. In that bow, the horn was very thin over the splice so the sinew would be thicker there. Directly over the thickest part of the horn, it was much thinner than elsewhere.

In another words- every bow was original. Dont exists same two bows . Only similar stile. You must try and have some experiences based on your succes or broke bows. Thats all. And teach from muesums or pics if you havnt in personal colection original like some pf Atarns :cry:

The existence of sinew layers on the belly of a hornbow is still confusing me... Especially near the siyah, where it becomes thicker, it adds weight to the bow end which must have negative influence on performance.

Maybe it was , as an additional layer, simply a protection of the inner core against humidity? I suspect air humidity to be exytremely high in most parts of India.

JJ

Since the sharply bent transition between the ridged and bending sections in these bows is the most vurnerable to failure, it should not surprise there is more sinew around that part and less towards the grip and the tips. I poked my bow with a nedle into the sinew there and found it was laid diagonally and lengthwise - it seemed the lengthwise fibers were on top of the diagonal ones. The rest of the bow had the belly sinew lengthwise. I am sure each bow is a little different though.

I see what you mean JJ about the great mass of the siyahs in the bow. I admit, over the years I have come to a conclusion that the bows (most bows) were not build for performance (I tried to pass the thought along in the forum with little response). It is because the composites of all styles are not really that different in this respect. It is just too easy to up the weight and get the faster arrow, while detecting small changes is just too difficult without the modern equipment. I now believe (pending further developments... 8^)) the bows were made for durability and the ease of constrution and according to the local preferences as to the shape for various reasons. -10fps sounds like a lot for us, but why not simply draw that bow a couple inches further to catch up?

Adam

The person who made the average crab bow had probably never seen a Turkish bow or a Chinese bow. He was probably familiar with the four major types of Indian composite bows, but may have specialised in just one. It is unlikely he had seen the construction of even a Persian bow, Since most of the Indian composite bows were covered in sinew and painted, it was unlikely he knew whether they had pieces of horn covering the whole width of the limb like chahar kham bows, part of the limb width like crab bows, or strips of horn in parallel like Persian bows. He most likely learned bow making from his father or uncles and he would not have been popular in the family if he suggested he knew a better way to make bows than his elders.

Innovation was not encouraged in traditional societies, but slow drift as details were forgotten and replaced by something expedient would have meant that bow design gradually changed. The build up of sinew on the belly side of the ears of crab bows would have reduced their efficiency, but the changes may have taken generations and in the meantime some other feature may have compensated. As Adam wrote, it might have been technically easier or more economic. With thicker sinew, thinner wood could have been used for the ears. Longitudinally laid sinew would still have compressed anything it surrounded so there may have been a trade off.

While I think that archers in those days may have been more perceptive of slight changes in arrow velocity as a direct experience, their expectations would have been different. Again, as Adam wrote, 10 fps might not have been important to them. For people who trained everyday, moving up to a heavier bow would not have been that difficult. If you found a bow that was more efficient, that would be a bonus and probably meant you would get your next bow from that bowyer. Competition like Turkish sport archery probably speeded up development and large armies with big demands for standard bows like the Chinese probably slowed it down.

Adam Karpowicz wrote:

I now believe (pending further developments... 8^)) the bows were made for durability and the ease of construction...

This points makes a lot of sense to me as a casual observer. Making composites is already insanely difficult, and you wouldn't want your efforts to go to waste with a fragile bow.