Why do bowyers leave space between horns ?

One more example from Yok Hua.

http://198.170.108.27/phpBB2/files/rem00043-1_201.jpg

I thought I heard from a Korean bowyer years ago that it was to prevent rubbing, but in relationship to what Adam said below, that didn't seem right. I thought about it more and remembered we weren't talking about the horn butts, but dojigae (teplik) butts! You have to leave a space between them when put on a bow or else they will rub. Shhhtupid me. :oops: :roll:

Ok, I never build a hornbow till now, but what I have read in preparation for this leads me to the following assumptions.
Due to the fibre structure of Horn a direct connection horn to horn at a place where some forces are transferred, tends the horn to split. Just if a harder fiber meets a weaker spot on the other side and there will be the start of a problem. Thats (in my impression) the reason why some bowyers place a piece of bone between the two horn stripes.
Second, if I mention the change in shape a bow takes over curing of the sinew layer, there will appear a gap between both horn pieces in the handle - just due to the change of the bow shape. So, if you prepare the horn to fit from the beginning you would end up with a (small) gap in the handle which, in fact, weakens the whole bow over time.
Taking both together it may be better lo leave a small (1cm) gap from the begining and finally, after all has cured, close this gap with a piece of material matching to the final gap and shape of the hornlayer.

Another aspect to the gap is it makes the bowmaking easier. I have found that the horn strips can slip a bit during binding. The binding holds the strips widthwise, but they can get a fraction out of position in length. The gap means that you do not have to worry about the movement, just cut the filler piece to match your gap. You can also tidy up the ends of the horn strips with a saw after gluing to get a nice butt joint.

Andrew

I would like to agree and elaborate with what Andrew said. While visiting Kim Park Young, senior master bowmaker of Korea, I asked him through a translator about the space between the horn slats on a bow he was working on. He seemed to indicate that the space sometimes just occurs during construction, as Andrew has pointed out, accidently. In that case, he would later fill the gap with a horn scrap or with horn scrapings mixed with glue! He picked up a pinch of scrapings off the floor as he explained.

As Andrew has earlier pointed out to me, bone has great antiquity as a reenforcing element in grips. Bone is possibly more porous than horn and might make a better patch. The squaring of the horn ends and obtaining renewed leverage also ring true. -j-

There is no "leverage" between the horn ends. The grip, being thicker, is under minimal stress, comparing to the bending section of limbs. The gap can be left between the horns, or filled with whatever the bowyer desires, for a neat joint. In Korean bows the joint is also covered with sinew under the grip wraps. In Turkish bows there is the chelik to tidy up, as Andrew is saying.

The importance of this joint is grossly exaggerated, for example is has been said the stresses there can cause slippage of the horn and that the chelik acts as a "shock absorber". These are myths with no basis in reality. Under no (or minimal to be exact) stress, the grip horns just sit there doing nothing.

Adam

Thanks for this explanations to all. I will follow this whem making my first hornbow.

I will concede that we might be talking about different bow making styles, but I have a Chinese Qing horn bow with about 2 inches of bone exposed in the grip of a piece which is probably 3-4 inches in length. The bow is much used with no failures obvious.

Seems like this joint was important to the longivity of the bow. -j-

The gap is provoqued by the reflex a hornbow is forming after the sinew- layers have been done.
It depends on the design of a hornbow too, cause there a hornbows with a slowly working grip-section, so the bowyer has to fill the gap very carefully with a piece of horn and to wrap it with sinew. If there is a non-bending grip- section, you can close the gap with whatever you want. A piece of bone looks well.
It is not possible to fill the gap with whatever you want, if the gap is within the working parts of the bow, so a mix of glue and hornsraps can?t be a reliable filler.

Andrew, I agree, but anyway I became furiuos about the lengthwise movement of the hornstrips when glueing them with the core, till I began to glue one strip, then waited 1- 2 hours till the glue has fixed the first strip a bit, then I butt- joined the next strip. I don?t believe in clamps for this job, I bind horn and core together.
Whatever you are using to glue the horn, clamps or binding, you can move the strip lengthwise with the clamps or binding while the glue is hot, it depends from the direction you fix the clamps or the binding. If you choose the wrong direction you will provoque a gap. But anyway, if you make a hornbow with a great reflex the sinew will form the gap when drying.
Widthwise movement is no problem, if the glue-line is profiled.

Michael

Rewdhawk, you are right in pointing out the gap can form only when there is a possibility of movement in the immediate area around the abutting surfaces of horn. However, in the common construction of the composites, where the core is considerably thicker in the centre of grip (plus around 1" away from centre), there is no, or minimal movement. The gap does not open regardless in which direction the bow is flexed - whether in normal use or during the reflexing caused by drying of sinew. The only chance of this gap to open is when the glue joint between the core and horn fails, such as in the case the bow is overheated.

It is conceivable, there are designs with the grip also working and flexing with the limbs. The Korean or Crim-Tatar or something similar to the Scythian may show some flexing. In such bows, the gap should be filled with a horn-like material and the grip covered with sinew to avoid failure when the bows sheds its string by accident.

Adam

Some of the Chinese bows, with horn or bone separating the strips, do so in order to make the best use of the long horn strips on the belly. The two joints still fall inside the non-bending section of the grip as Adam described for the single chelik or ibranjak.

If you are making a bow and your horn was only a few inches short of what you needed it is easy to insert a strip at the handle. I think this has a different origin than the chelik or ibranjak, but the physics are the same. I am sure I have seen an X-Ray were there are two joints and both have a bone strip inserted in them in a Chinese bow.

Adam, that?s right, in almost every hornbow- design the grip section is to thick for noticeable movement.

But did you ever think of enforcing the reflex and the drawweight of a hornbow by cutting the hornstrips additionally in the working parts of the limbs, to bend the bow backwards and to fill a now more or less opened gap with a fitting piece of horn?

Michael

Bede, I have seen a Turkish bow with two cheliks, still however in the non-bending centre of grip.

Redhawk:

This type of treatment is a diffrent matter altogether. It is possible to force reflex after attaching horn and fit in more material if a gap opens at the butt joint positioned in the bending section of limbs. The gap will, in any case, be tiny, unless the adhesion between the horn and wood failed there. The problem is, this spot in the bow will be weak, because it is impossible to make the butt joint there so perfect, as the untouched horn around it. This will in effect make a hinge in the limb and it will flex there too much. The place can be wrapped in sinew of course, and the bow will function, but it will be a "broken" bow nevertheless and its perforance will suffer.

Adam

Adam,
The Chinese bow I saw was the same. The grip was much to thick to bend.

Sorry to thank you all for your answers after so many days.
I am just back from a holiday in a lonely village.
I believe the answers will be helpful when I go to the step of gluing horn and core.What you said also gives me answers for some other questions in my mind.

I own a number of old Chinese bows. One particularly well made bow with golden transparent horn has it's horn join at the handle with nothing in between. This bow was identified by Stephen Selby as probably made in Xian.

Another gigantic Beijing made strength testing bow also has the large slabs of horn (50mm wide at mid limb, total 54 cm long) join at the handle. The horn slabs stop no less than 6 cm before the knee of the bow, most likely because the horn just didn't came any longer.

Yet another Beijing made bow, this one for archery with signs of extensive use, has the horn starting on either side of the the handle and running all the way up to the string bridges, they even make the bend with the knee.

A fourth bow (Xian made) again joins the horn slaps at the handle.

I tend to think that it doesn't really matter if you let them join or not, and what kind of material you put in between. It is simple wood for that Beijing made Manchu style bow described above. I can imagine that some types of bow create a gap there as they are being forced into a C like is the case with Turkish and Korean bows.

-Peter

[quote="wk1234wk"]Dear all,

There is a question in my mind and it has confused me for a long time.
Why do traditional bowyers leave space between the horns?

I have another question, if it possible or advisable to use more than one piece of horn on each side, I do not have long enough pieces to use, would it be possible to say make 1/4 in wide strips and stagger the joints, leaving no space between the ends.