Crab Bow Measurements

jkekoni · Post by **jkekoni** » Wed Dec 02, 2009 8:45 am

there is an angle around 25cm from the tip. Oddly the limb thickness/widths are not affected by this.

Is the whole siwayh rigid on wood only, or is it bending with horn/sinew or something in betheen?

Bede · Post by **Bede** » Thu Dec 03, 2009 7:37 am

There is a transition between the triangular kasan-like part of the gosha and the bending part of the the limb. There the thickness changes abruptly. The whole of the siyah or gosha is rigid. When the bow was heavy enough to require it , the tip section is spliced into the triangular section so that a heavier stronger piece of wood can be used. This is the purpose of the horn inlay in the tip too. The only part of the bow that bends are the sections between the grip and the siyahs.

The bow makers who made these bows went to a lot of trouble to make sure the limbs were stable and the siyahs were rigid. Those who understand the equations will realise that there are minor movements in the rigid parts of bows, but they are usually so small as to be not noticed by the human eye.

jack farrell · Post by **jack farrell** » Thu Dec 03, 2009 1:20 pm

On some old bows the tip has been entirely eaten off by insects. This may mean that the entire tip is horn. We all await construction details.

Bede · Post by **Bede** » Fri Dec 04, 2009 3:27 am

Jack,
Do you mean all of the tip above the nock or the whole slender portion of the siyah?

I have seen old Manchu bows where the very tip of the siyah was a buffalo horn insert and the nock was carved in it. There are also Turkish bows where a piece of ivory is inserted for the full length of the baş so that the nock is carved wholly in ivory.

jack farrell · Post by **jack farrell** » Fri Dec 04, 2009 12:18 pm

Crab bows I have seen are lacquered/painted entirely and this limits intrusion by insects. Just before the bow is strung for the first time, the nocks are cut at the tips. Old bows sometimes have the tips missing entirely which is a clue that the nock was cut in solid horn; in the manner of some Qing bows.

I would like to see a drawing of the complete construction. Was your x-ray successful?

Bede · Post by **Bede** » Fri Dec 04, 2009 1:05 pm

Jack,
I have seen bows where a tip has broken. Usually there is a bit of wood on each side. It always looks like the horn was eaten out to the notch for the string and the tip snapped off because it was weakened. I have one like that so I will get it out and have a look.

I have an idea for scanning the X-Rays. I am going to duplicate the setup for slide copying by putting a reflector above the film and see if that will give me a better image.

The wooden core and elements of the paint seem to be denser to X-Rays than the horn or sinew. I picked a bow to X-Ray that had most of the paint abraded away, but even so there were flecks of dense mineralised paint.

Andrew Hall · Post by **Andrew Hall** » Sun Dec 06, 2009 10:19 am

Bede, sorry for the delay in responding.

The bows mentioned by Nicolle were reportedly found in a collapsed structure with a large number of other military artefacts. Although the carbon date error ranges are missing (and may well be large), a number of the finds were carbon dated and these cluster the first half of the 13th C. The bows are only illustrated as simple line drawings, but show bows with no set back in the grip and a smooth curve into the (possibly triangular cross-section) siyah.

The Turkish bow seems fully developed by the Bayazit period in the 15th C, and in the 14th C Taybugha describes bows that seem to be Turkish/Persian. I would not have thought it impossible that bows with Turkish/Persian-like characteristics (no grip set-back, smooth curves into siyahs, horn on siyah belly) were present in the 13th.

(I wonder if Tatbugha's munfasila bow type ? that comprising several elements fitted together ? was the term for the older angled-eared bows).

When do you think the general Turkish/Persian characteristics developed?

In terms of shape, you can get a crab-like bow by taking the more reflexed of the two Shiluustei sum bows, extending the horn and sinew up the siyah and widening it. As you discuss, the construction is somewhat different. Is it possible that the shape was fixed by tradition, but the bowyers changed the invisible core construction to make them easier to build?

The stripped down crab I have seen had long V-splices to the grip, and evidence of another in the kassan/sal boundary. The siyah still had its covering and sinew, so no other splices were visible. The tip is of wood only.

The horn only covers about 3/4 of the limb width, the remainder is filled out with sinew. The Pitt-Rivers museum has a number of sectioned composite limbs, including a crab bow which has the same form. The overall quality of construction did not seem high ? wavy grain in core, inconsistent core and horn thicknesses etc ? though the bow had broken in one limb so may not have been the best.

Andrew

JJ · Post by JJ » Mon Dec 07, 2009 12:55 pm

Hello Bede, very good information! I?m wondering how such a sharp bending in the beginning of the ear can be achieved. Possibly the only solution is using natural curved parts of trees. I tried some maple soaked in water for about 2 weeks and it broke. I have yet to try fresh yew, maybe it works. Yew can be heat bent very good.

Andrew, you mentioned illustrations depicting these 13th century bows; could you post some of these here? I?m curious about these bows. The invention of the "modern" composite with contact siyah/ string bridge is a very interesting question.

Best regards, JJ

Andrew Hall · Post by **Andrew Hall** » Mon Dec 07, 2009 6:46 pm

JJ
The drawing is copyright so I am afraid I cannot post it here.

Andrew

Dusan · Post by **Dusan** » Mon Dec 07, 2009 7:48 pm

I dont know about net copiright ,but newspapers law about pics and drawings works if you describe source near the pic.

Daniel T. · Post by **Daniel T.** » Tue Dec 08, 2009 6:54 pm

JJ wrote:Hello Bede, very good information! I?m wondering how such a sharp bending in the beginning of the ear can be achieved. Possibly the only solution is using natural curved parts of trees. I tried some maple soaked in water for about 2 weeks and it broke. I have yet to try fresh yew, maybe it works. Yew can be heat bent very good.

That is a good question. Judging by the centimeter grid in the pictures, the triangular part is about 1,5cm thick. This must be hard to bend in this small radius.
I could imagine that it is spliced similarly to Kviljo's construction seen here: http://198.170.107.188/phpBB2/viewtopic.php?t=1465
The X-rays should tell.

Daniel

Bede · Post by **Bede** » Thu Dec 10, 2009 5:37 am

I have just checked the X-Ray of a similar crab bow and, at the point where the limb is about 21 mm thick, the wooden core is about 10 mm. The Koppedrayer bow is similar if a little thinner in the core.

I believe from looking at the cut up bow and the x-Rays that the bend in the siyah is artificially produced. I am not saying that you couldn't make this kind of shape with wood that has grown to the right shape, but bending is more straight forward. Considering the amount of sinew that has been applied to the back, a slight weakness in the core would be insignificant. I have some sandalwood that has a branch coming out on one side and I will try to use this for siyahs, but I think the other way will be easier and is more likely for traditional commercial production.

Making some deductions from the X-Ray, I would guess that the core increases in depth immediately after the bend. This might even reflect the way in which it was made. By changing the thickness of the raw core, a weak spot could have been made where bending would occur preferentially near by.

Daniel T. · Post by **Daniel T.** » Sun Jan 03, 2010 7:04 am

Bede, do you know the draw weight of the measured bow? Around 100#? Around 50#?

Bede · Post by **Bede** » Sun Jan 03, 2010 11:56 pm

Daniel,
I have no way of measuring the bow for weight. I really need an exact replica to get some idea. The bow is several hundred years old (between 150 and 250). I can get the mass of the bow. Some experienced bowyers may be able to make an estimate from that and the dimensions.

Daniel T. · Post by **Daniel T.** » Sun Jan 24, 2010 11:51 am

What is a typical width of a horn insert for ear reinforcement? Is it a slim insert, maybe a bit thicker than a horn insert for arrow nocks, or is it the bulk material?