Turkish Bow Beginner Project

I would like to ask Adam if he thinks the cracked core could be salvaged. Considering that material could be removed from the kasan eye on the belly side, I wonder if the crack is local to the layers that are broken or represents a visible indication of a more serious problem.

The second core looks very well. I would discard the first one.

The grip splice is best extended further into the grip - all the way to the places where the grip is the narrowest (about where the future arrow pass will be located). Then the V-splice will be longer than 4in and its base will be less wide - around 3/4in. I understand by the "transition" you mean the flare-out (in width) from the grip to limb. This varied in different bows and is not critical, as long as the thickness of the "flare-out" is adjusted for correct bending there in the finished bow.

The horns are Ok as far as the length is concerned and yes, the 10% means 1:9 dry glue to water by weight.

Adam

Were abouts in SD are from? Don't see too many Asian archery lovers around these parts.
JonR

JonR, I live in Sioux Falls, where are you located?

As for the interest in Asian archery, I received a compound bow for Christmas two years ago, last year I started building selfbows which has turned into a passion to build all kinds of bows. My problem is I have several different projects in various stages. I most recently got my hands on the video All Tied Up in Bow Making by Jaap Koppedrayer, with hopes of building a bamboo yumi bow.

I live just down the road in Canton. Made a lot of self bows a while ago but never tried a horn bow. Was always on the list but never got it done. Shoot a number of "Asian" style bows but one of Japp's has also been on the wish list.
JonR.

I have the limbs joined and the horn glued. I used a spacer in the handle to get more length out of the horn strips, I used camel bone inlays for the joints. My question is about how much reflexed I should be adding after each layer of sinew. Adam's book says I should end up with now more than 4 inches between the tips. I currently have 34 inches across from tip to tip. Note the tips have an extra two inches that will be cut off. Do I pull the tips closer by 10 inches after each layer or start with less on the first layer of sinew and larger amounts with the last two layers of sinew? I just want to prevent any damage after getting this far. What does every one else here do?
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10in after each layer will be about right. The fadeouts close to grip seem a little too thick - I would reduce the thickness of the core there to have the limbs start bending closer to grip in the finished bow.

Adam

I took Adam's advice on the fadeouts near the grip, (thank you Adam). I have since applied the first layer of sinew and it went on very well, but now with the second layer I have some of the sinew with tangled strands, mostly in the joints of the sinew bundles. I think it is on the surface but I can?t be completely sure how deep. I will plan on sanding the tangles off but I don?t want to remove anymore than the high spots. How critical is it to have straight strands of sinew? Does this matter?

This entire project is on an increasing stress scale, the more time/money invested into this bow the more I worry about screwing it up.

Progress update:
I have glued on three layers of sinew and now can rest for the next 6 months. I have never worked with sinew before and so it was all new to me. I used elk sinew which I thought was hard to process but I hope it will make a strong bow. I maybe was able to use 45% of it, the rest was scrap. As for gluing the sinew I used 100% sturgeon air bladder glue. I first tried to soak the dry sinew into the glue, it was impossible to straighten out and it soaked up way too much glue, I ended up removing all of it half way through applying the first layer and starting over. I found it worked very well to soak the sinew in water and then comb out any tangles and then press all of the water out. I then soaked the sinew in glue. By doing it this way the already wet and combed layers of sinew keep a flat shape that I could lay right on the bow. I used a scale and split up each layer into several equal mass strips to apply. After the sinew/glue gelled I wired the bow with some added reflex, I was amazed at how much reflex I was able to pull in and how within a week the reflex held even when I removed the wire. Please give me your thoughts or questions.

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nice idea on drilling through the tips.

How long are the horn strips? how Wide? how thick?

This is great. :D

Can you do like a recipe and put an 'ingredients' post in, listing the things you needed, where you got them from and roughly the cost? It would also be good to list the tools you're using a show photos of any unusual ones.

Stephen

I have finally typed up an ingredients list. I have posted it in the Where can I get...? forum.
As for the cost I ordered several items in bulk, but my best guess for the materials plus shipping for one bow would be 225 USD. Add in a few tools, Adam's book and I think a person could have their own Turkish bow for 300 USD.

http://198.170.107.188/phpBB2/viewtopic.php?t=1868

Radius, for the horn I started with 65 - 70cm length horns from Highlandhorn and worked them down to about 5mm. I then followed Adam's recommendation and boiled the horn for 10 minutes. I proceeded to clamp the hot horn to a flat surface. Now with the horn fairly flat I worked it down to 3mm. I did most all of the horn work on a table top belt sander with 50 grit.
The width of the horn at the sal measures 1.125" and for each half of the bow the horn measures 17.25". Note I added an extra 1.5" spacer of horn in the handle as I was only able to get 16.5" out of the horn. I may have been too carefull as I made sure there were no flaws in the horn (cracks, ect). I would get the 75 - 80cm length horns next time.

My first turkish bow is just days away from 6 months and will be ready for tillering. I have previously shaped the bow tips and also have filed/sanded the bow to symmetrical dimensions matching what my original drawings called for.

Adam writes in his book that you start with a special tillering tool called an asa gezi. I have crafted my own version that I hope works well. My question is how much reflex do I open up with each tillering session and how much time should I keep the bow in this new position before spreading the bow futher?

Cured Bow
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Tillering Tool
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great tillering jig, i'm going to make one like that. How long are the segments?

Looking great so far.
This part is scary! It takes a lot of effort to spread the tips apart. Try to get them so the tips are basically pointing straight up when the bow is put on a flat surface. I found using a foot on one tip and a hand for the other tip worked well and meant I still had a hand free to insert the tool.
Good luck.

Ok so I have started to open up the reflexed bow. The below picture shows my progress so far, but when I remove the tillering stick the bow returns almost all of the reflex. I have not yet started to reduce any horn or sinew or use any heat. How long do I need to leave the tillering stick in place? I left the bow over night and this morning when I removed the tillering stick the bow only held open 10". With enough time will the bow hold an open shape? Per Adam's book I am trying to open the bow up to a point where the tips point straight up. I am holding off reducing material or using heat for as long as I can.

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if it springs back every time, maybe the trick is to spread it farther than it needs to go? It looks like your jig may be too short

The tillering tool will not by itself reduce the reflex. You need to heat both the kasan eyes with the tool in place. Do not heat the sal area. You are aiming to get the kasan eye area hot enough that the materials plastify and the tool is there to hold the bow in the shape you want as it cools.
I'm no expert but to my eyes you seem to have too much reflex in the bending sections and your tillering tool is definately too short. Get it so the tips are past straight up and down - maybe another 8 inch longer tool.

Yes, the tool serves to pre-stress the bow to see potential problems which need correction: twist in the limbs or the lack of symmetry in each section, plus the excess of bending in the kasan eye. Your bow seems OK as is (the limbs look symmetrical and do not seem to have twist), although as Mike said the tool should be extended until the tips point up. For now, the kasan eye section looks open enough, unless you want to open the angle further for better stability in the bow. If no problems are shown with a longer stick, the tillering can continue with the next tool - the formers for bending the sal sections and the bow can be strung.

Adam

I had some more time to work on this bow so I made a longer tillering stick and opened the bow up some more. I heated the Kasan which helped open up the bow a little more, probally 16" inbetween the tips when at rest. The tips where slightly out of alignment so I heated up the sal on each side without the tillering stick NOT in place and then twisted the bow to counter the misalignment. Once the bow fully cooled the tips where in line. Next up I made a pair of tepeliks and after a little flexing the horn delaminated in the sal and cracked. It would seem that there was a small section of the horn that must not have been glued well enough as the horn on each side of the delamination held.

Ok so on to the next bow... My guess is that I did not do a good enough job sizing the horn and maple core before the final horn/wood glue up. I worry that there are air pockets in the glue layer inbetween the horn and wood. One idea I have is to get a custom router bit that will help make matching grooves. I think matching grooves would be one less point of failure for the next bow.

If anyone had additional thought please let me know as I do not want to repeat this mistake.

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Glue may not have been wet when joined- dry join. The proof would be seeing squeeze out. Look at the faces of the join for evidence. Post picture.

Ok I peeled back the cracked horn and the joint to me looks like there was very little glue in it. I know when I glued the horn to the wood core there was glue squeezing out on all sides. Did I squeeze out all of the glue? I did use "C" clamps. What now?

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It could be air pockets formed in the glue as it dried - possibly not enough glue in the joint. Sometimes, a particle of wood dust can get in between the surfaces, preventing good contact when clamped. Without the contact air bubbles will form when the glue looses volume as it dries. Ideally, the clamps should squeeze the the drying glue for a perfect film of solid glue as the end result.

I notice a discontinuity in the core's grooving, which could contribute to the failure as well.

Adam

I?m only guessing but maybe my opinion helps you in future. Other than air-bubbles? assumption, pls. see my points.

1. I usually do non-matching grooves. In order to increase the surface of layers, I use much smaller teeth?s tool (eg. metal saw blade) for grooving. I thing for non-matching gluing, your grooves are a little big (surface too small).

2. Other point (sorry but I can?t see correctly in pics), the cross section of groovs look like ?U? shape instead of ?V? shape. Again, for non-matching it?s not the best form.

I have started the second round for attempting a Turkish Horn Bow. You can see in the above posts some of my progress and ultimate failure with my first bow.

Earlier this spring I ordered green sugar maple. As previously done I soaked the maple for several days and then after boiling for an hour I bent the core over a plywood form. For whatever reason I had a very difficult time bending the cores, many of them cracked and split. I tried reducing the sharp bends on the forms which helped. The cores were failing in tension. Note, I was trying to bend 1/2" thick cores. I reduced some material on the outside edges of the form side of the core, this seemed to helped as well. I think the key here is only the very best straight grained maple will hold up the such extreme bends.
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As for core materials when I initially read through Adam's book hard maple was at the top of the list. After some more research I have read that Red Mulberry can and was used for the core. I would be interested in hearing how Red Mulberry heat bends and how well it accepts glue as I have an unlimited local free supply of all the Red Mulberry I want.

I ended up with two good cores after all of the trouble bending them. Yesterday I spliced the cores together and now am ready to start working on the horn strips. You can see in the below picture I am experimenting with various amounts of built in reflex, this can be seen in the top core. The bottom core shape matches the profile from my first bow attempt. The handle piece is 14" long with the splice running 5" long. Both cores will have an overall length of 44".
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Last comment, I have a similar post about my work on building a Turkish Horn Bow on PaeloPlanet and the discussion came up about the quality of horn that is available for the novice builder. I have most recently ordered 75-80cm long horns from Highlandhorn. Note I am very grateful that there is someone out there that can reliably deliver as I got burnt on my first try at buying horn. My problem/question is that I am just barely able to get a long enough horn strip out of each horn. There always seems to be a groove that is two deep. I can?t imagine trying to get a horn strip for longer heavier bows from the horns I have so far received. Where is everyone buying horn?

Thanks for reading, all comments welcome.

Red mulberry is some of the best material i have worked with so far,bends extremely well with steam and absorbes glue kust as well,follow Adam's advice on sizing with thin glue before trying to laminate the horn.
P.J.

Last week I milled up some of the mulberry I had cut last year. I soaked the strips in water all week and yesterday I boiled them for an hour and then bend them on my forms. I got to use my new boil pan along with two coleman stoves and was very pleased with the results. I think having a good rolling boil for the full hour is key to bending wood (mulberry or maple). The mulberry bent excellent.

Note in the boil picture I started with mulberry staves with poor grain, just to get a feel for how they would bend.
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My question for everyone is about the quality of mulberry. I wasted a lot of material in finding good straigt grain staves. For the most part the stave follows one growth ring with just a small amount of run off. Mostly just swirls from nearby knots.

What has everyone gotten away with when using mulberry???

Also what about pin knots??? The below two pictures show some pin knots, in both cases they are located about in the middle of the kaksan. Will I be ok???
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More grain pictures. Am I ok???
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very nice, i hope those pin knots dont weaken your kasan, usually they are avoided in most under stress parts on any wooden material.

good luck!

• bheggeseth
  I also did an experiment with mulberry core and side strips horn. horn is 3.5 mm thick, wooden core - 5.5 mm. the first picture - the bow is stretched without sinews .... I wanted to feel how it works mulberry :lol: . the second image - after the last layer of sinews. I am optimistic that mulberry is not a bad material.

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Pazuzu, very nice bow. My current favorite selfbow is a 64" flat bow made from mulberry. I agree that mulberry can make for good horn bow. Zarasp, thanks for your thoughts, I think I will discard the two that have pin knots. That leaves me with one mulberry core for now.

Pazuzu, can you describe the mulberry you used, how perfect was the grain. The below picture shows the two best staves. I think I will need to go back and mill some more mulberry. I am spoiled with the hard maple I bought, it has absolutly perfect grain, but I can get mulberry for free.

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bheggeseth
Mulberry we work with is an old tree - perhaps 20 inches in diameter. naturally dried for one year. fibers are not parallel very well - like your handling of the photo (above). I also prefer acer tataricum with paralel fiber, but used for projects of Ottoman bows. This is just one experience.

Bhegg; You showed the outer curve but it is the inner curve which will be stressed.

I now have three wood cores joined and am ready for horn. After the trouble with the last bow I looked for a different way to precisely mill grooves in both the core and the horn. I had a custom router bit fabricated with equilateral triangles spaced at the proper dimension to give a 2mm deep groove. I have made a jig to wrap around the router bit which I can adjust to allow the bit to cut at just the right depth. Then I clamped the bow core to a sled which I can slide up against the router bit. Overall the process worked very well and will give the bow matching grooves.

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PAZUZU,
I do not know what bow did you reconstruct but it looks wonderful to me.What splice did u use?
Поздрав
Bheg, nice grooved horn plates.

I have just finished up gluing horn on two new bows and I feel I have improved the quality and process. I used a custom router bit for grooving and sized the core and horn with 20 coats of 2% glue. With using 2% glue I had no problems with air bubbles. Note I did not use any heat on the parts during sizing, the work shop is at approx 72F (22C) and the glue is heated to 145F (63C). For the first bow glue up I used 35% glue but I felt it may have been slightly too thick. I was able to easily fill the grooves on the horn and core with glue and then clamp the horn to the core with ?C? clamps. There was plenty of glue squeeze out on all sides, As I started clamping at the handle and moved out to the tips I could feel the horn lock into the matching grooves. I have a leather strip with small wooden blocks glued on that I use to distribute the clamping pressure on the horn. I used halogen lamps to heat the horn and core. On the second bow I mixed up 30% glue which I felt was just right.

I have one more bow to glue up before I start preparing for sinew. Any thoughts or comments are welcome.

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you shall now rename your post to "turkish bowmaking for runaways"
:-)

How did you make the grooves into the blade, or did it have them made in the factory?

This is absolutely stunning invention!

The custom router bit was made by Farr's Custom Carbide from Santa Ana, CA. I called several tool makers before finding one that could make what I wanted. When I first called Farr's they confused me with a past customer. Someone in the medical industry was having a very similar router bit produced. They were planning on using it for preparing cadaver bone to be spliced into patients. Farr?s used electric discharge machining (EDM) to make the bit. This involves running high voltage through two small wire electrodes. This process slowly eats away at the bit until the desired profile is created. All of the other tool makers I called where not able to make the bit due to the very fine sharp angles needed.

I now have just finished grooving the third bow using this bit and I am very pleased. There is some time involved in making the sleds to hold the horn and core but the results are perfect matching grooves. Note this all comes with a high price tag, approx 325USD, the bit is carbide and should hold up for hundreds of bows.

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I so much hoped that it would have been a mass produced tool made for some other purpose.

$325 is a lot of money, but actually a magnitude cheaper than I assumed for a custom made tool.

Have a look at this: http://atarn.net/phpBB2/viewtopic.php?t=1015
I copied this, it is nice although it is only about 30mm long. Of course one can always make two passes when 30mm are not enough. Or simply do the rest with a hand tool. It is easy when most of the horn or wood already has perfect grooves acting as guides.

Daniel

As noted earlier I am working on my second attempt with a horn bow. I have two maple core bows and one mulberry bow that I am presently working on. Compared to last year?s failed bow this bow core seems very flexible. Looking back on my first horn bow attempt I think I left the core way to thick. Some of the measurements on the failed bow match up with 200 pound bows listed in Adams book.

Below I have a picture of the first maple core bow with thickness and width measurements along with total length measurements. I plan on the sinew to add approx 3mm and I shaped the core with that in mind. The horn is 4mm thick and is glued on with well matched grooves.

I have a goal of 70 pounds; does anyone have any comments about the core dimensions before I add the sinew? I am slightly worried that the sal/kasan transition does not thicken quick enough and may be a weak spot.

Second attempt (bow 1 of 3)
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Note (W = Width T = Thickness)
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hi bheggeseth,

second half of kasan looks to much rounded. this can cause problems with stability when braced and shooted: string lays on belly. to prevent this you need an enormous braceheight or stringbridges.
perhaps you can make it more straight, bending it carefully back with heat.

Peter

Thanks for the advice Kyudohund. I steamed the kasan/tip bend and tried to straighten out the bend. I am not sure if I helped it or not. The bottom bow in the picture is the one in question, and for reference I used the same core form for the middle bow. Also I now question the other two bows I am working on. Should I continue trying to adjust the bends or just move on with sinew? Comments?

Also any thoughts about the thickness and width from the previous post and picture?

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bheggeseth,

i am not an expert, but until now i got 6 bows ready, 3 failed. i only can convey my experience i did in this short time.

kasan looks much better now. unfortunately you straighten kasan-tip angle too. But this can be corrected by glueing a wedge on the back of tip, without, or only less, reducing thickness.

your first bow in this topic, the one which broke, had a very good shape!

keep in eye how all sections shall look like, when the bow is strung. seen for the bow in the middle, when string should not touch the belly, you get a nearly right angle between sal-end and string.

the upper bow looks good, keeping kasan bit shorter.

aiming 70pds at 28inches, thickness mid of sal i would estimate <11,5 mm. sal is short. perhaps Adam or Cem can give an advice. width is not so important for drawweight, but stability.

hope this helps

Peter

I was able to get three layers of sinew on the one of the above three bows. The core weight was 205grams, I applied 77grams of sinew and the current total weight is 310grams. The sinew process went well; the key for me is to run through a ?dry? process first to make sure you have everything ready. I ended up with an unsymmetrical ?C? shaped core which should tiller out. More concerning is that the handle/sal/kasan/tips do not line up in the same plane. (this bow is the bottom bow core from above post picture of three)

Sinew materials all ready to go; I have been using a halogen lamp to heat up the bow core.
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Unsymmetrical core.
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Top view of bow. Note center line is not in the same plane.
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My next step is to pick which bow I will work on next. After reading some of the advice received from questions I placed on this forum, I see two potential problems that are present on the set of three bows I am batching. First problem is the rounding of the kasan shape and the second problem is with how I have shaped the kasan/tip transition. With the time and cost of sinew I am not sure if I should proceed.

Most recently I have prepared two mulberry cores, I was able to flatten the kasan section while increasing the kasan/tip bend angles. Note on one of the bow cores I have added some extra reflex initially built in.

Mulberry cores bows, hard sugar maple handle, tips 14mm thick, 44" total lenght.
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I'm sure you will have no problem straightening the twisted tips and limbs after it has dried fully. My last bow also had similar "defects", but it is still in one piece. There went a lot of patience and carefullness into the process, however.

If there is not enough thickness in the tips after you have shaped them, you could add a small piece of wood to the back of the core. It will all be secured by sinew in any case. Having the tips dissect the string loop in a good manner must help a lot with stability.

Oh, all of these projects popping up from around the world makes me feel the urge to continue on mine too.

I am working on the second round of bows and the first of these bows has now been drying for three months. I clamped the bow tips under some pressure for the last two months to try and straighten out the limbs as they were not in the same plane. This worked quite well.

Using a caliper I reduced the sinew where needed and I now have symmetrical dimensions for each limb. As you can see from the picture the right sal is much stiffer and the kasan/tip on the left has a tighter angle. Right now the thickness and widths all match. Note I used a caliper when flatening the horn and shaping the core. If I understand correctly Adam's book stats I should work on getting the kasan/tips to open up equally first, then work on the sal. Should I use heat or should I reduce some material?

If I reduce material the limb thickness will no longer be equal. Is this OK? What is my next step?

Tips are untied, bow is ready for tillering.
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Starting to open up the bow, note uneven limbs.
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- heat the kassan eye and open this part to get equal angles there.
- open bow over several days, preferably without heat, to C-shape
- if limbs are disbalanced, tiller
- open further with tepeliks, apply string, tiller
good luck + keep us updated

:P

I have applied heat in the kasan eye area as well as in the tip to help open up the left side. This did help although part of the problem is that the steam bent tip itself has a sharper angle than the other tip. I have removed some material from the right side sal (no heat) and so far the bow has started to open up nicely. I am at the end of the asa gezi, the plan is to leave the asa gezi in place over night and then tomorrow I will start working the bow with the next longer asa gezi.

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I had the same problem with tip angle. with a lot of heat and force it can be corrected (but if you heat it again later in this area it has a tendency to go back).

Ok so I got the bow opened up evenly and started working the limbs with the tepeliks. As seen in the below picture. I tried to continue bending the limbs when I got a total failure. It looks like the horn lamination held, so that is good news but what do you think the problem is? It looks like the wood and sinew cracked very sharply? Note the relative humidity in the house is at 45%.

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Some more details, the break was in the middle of the sal area. Also my best guess as to the problem is that I did not have enough sinew covering the sal. At the break there is approx 4mm of horn, 4mm of wood, and 2mm of sinew.

That makes me want to cry. It was looking so good! Others with more experience than I should chime in, but I think you're right - it looks like the sinew failed first.

You certainly can use more sinew to be safer, but 2mm should be enough. Heavy Turkish bows had 2mm sinew (as measured at the centre of limb - the sides have thicker sinew).

The break looks odd somehow, especially the break in the core. A limb would need to be severely overstrained for this to happen. I see you tied the tepeliks quite far from the kasan eye. They should be tied right below there, so the entire sal is evenly bent down, from the kasan eye to the grip, onto the tepeliks to spread the stresses over more length of limb. And, as I hope you had done, the sals should be tapered a little as well for an even bend.

How long the humidity stayed at 45%? To be absolutely sure the bow is well aclimatized, 2 weeks are safer. 45% in a winter heated house sounds high. I suspect it could be lower than that and perhaps the bow was dried too much during the heat corrections you had to make.

Adam

Throw away those tepliks :)
Heat the bow 50 celsius, bend it over knee to C shape.
Make a bowpress heat and put on a string, leave it with string rest of the day. Heat some and draw half, let it cool. If you lose much reflex, heat it and reflex it to C shape.
A hornbow has to be temper just like steel :)

First thank you everyone for your thoughts, without all of you I would never have gotten this far. I have a cheap plastic humidly gauge so I guess the humidly could be wrong, note the gauge and the curing bow have been in the same room and has read 45% for the last few weeks. I did use heat for corrections but not on the sal area. Now looking at the tepeliks I can see that I had them placed very close to the grip. What is strange is that I was only trying to bend the bow just a little bit more when it broke. The bow would have needed to bend much more to reach any kind of full draw.

The last bit of info is that the bow has been resting inside the house, 45% humidly, 70 degrees F temp. I have been stepping into the garage to tie on the tepeliks and do any bending. This is no more than 20 min at a time and then I bring the bow back inside for studying the next step. The garage is approx 50 degrees F, I am not sure of the humidly there.

So for lessons learned, tiller bows in the summer to be safe, ensure there is just a bit more of sinew covering the sal, concentrating more bending in the full sal, is there anything else? The plan is to start applying sinew to one of the next cores that I have ready. I also am waiting on some horn as I have two bows with improved core shapes that I would like to try.

My next roundup: the top bow shows the where break in the sal was. The next bow has been built with some added reflex to design, it has the horn glued on and is ready for shaping and then sinew. The bottom two cores are mulberry with hard maple handles. Here I have flattened the kasan sections, I will be trying one standard bow and one with added reflex.
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My gut feeling is that the reflexing process of the wood is actually causing compression damage on the back of the wood core.

When you try to open up the bow those compression fractures open up and the sinew isn't quite enough to hold it together.

If you were to flex a regular self bow to that degree and then bend it backwards it would fail in an identical manner.
I think the combination of overheating the wood and bending when it is too thick is causing a lot of hidden damage.

To me it seems that curve would be better mostly glued in rather than being forced to bend that way initially.

The bow that broke started with the below shape. No forced bending just glued core with horn laminated on.
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As for the middle two bows in the above picture all of the curves were the result from boiling and clamping the cores to curved forms. Maybe a little reflex glued in from the handle splice. Should I stay away from these bow core shapes? Does boiling the cores and then clamping them leave the wood cores weaker?

:shock: oh gosh.. my condolences

same thoughts:
- tepeliks were not at right place, should be near to kassan eye.
- of course a safe way is to heat the bow as Redhorse suggests.
- use MORE sinew

I still think it must be an incredibly delicate balance where a bow is bent so far one way and then asked to bend the other way.
Can the sinew backing stop the core from being compressed during the reflexing process? It seems unlikely that it is totally protected just because it is "buried".
If we were to sinew the belly of a selfbow and then overdraw it I can't see why it wouldn't chrysal underneath the sinew.
Another thing I don't quite get is that people say horn can't take tension. Is this really true?
It seems that it must be quite capable of taking tension because it is kind of asked to be a "back" when it is being reflexed so strongly.
If it isn't actually stretching in that application then the core and backing must be undergoing quite significant compression as the bow is reflexed. Hence the potential for damage. It can't just be reflexed with nothing happening to the materials.

how much time did you give the bow to adapt gradually to the tepeliks ?
should be some days..

I'd say the reflex (pre-tension) is needed to compensate for creep in the materials later on. the wooden core gets surely compressed on the back.

usually with a composite bow core break you get a slow delamination of the sinew and weakening of the respective limb, no sudden total break.
so for this total sudden failure maybe the sinew gave up first.

horn is brittle to tension but can take an incredible amount of compression. when heated (seasoning/reflexing) it's plastic deformation.

I am worried that maybe I rushed the whole tillering process now. How long should I spend on each step? Should I be leaving the tillering tools in place for hours/days?

Over the course of 5 days I worked the bow with the asa gezi, twice leaving the asa gezi in place over night. I applied heat to the kasan eye and kasan/tip in an effort to open this area up and also I was trying to open up the tip that had the sharper angle in an attempt to make both tips symmetric. I had the bow opening up nice and even with the asa gezi to the point where the tips where parallel to each other. The bow did not have any twisting. All was looking good.

The earlier picture showing the tepelics in place was the first time I had used them. They were in place probably about 20 min. I took the picture and then I tried to further bend the bow on the tepelics. Thinking back the bow had no place to bend but near the handle. Still I am surprised that the bow broke like it did. I thought these bows where ?tough as nails?. Once you have a fully tillered functional bow how fragile is it?

Ones you get it around it will take alot of abuse.
First bend around the "corner" is the critical part.
A safer way is, bend it around after a few weeks drying :)
Does it lose? I don't know. My fastest bow 190+fps/10 grains, I did brace when it stop losing mass, a few weeks.

The sinew looks like it follows the curvature of the sal, without the flat top and thickening at the sides. Could that have been a contributing factor?

Best thing is to learn from a failure like this. had some of these too ;-)) (and still trying to learn from them)...

I think it is a fault in the sinew that caused the break. Your tepeliks were too short and not put on the right place, but ok, a break like this one should not occur with good sinew. I don?t think it is because of low or high humidity either.

What kind of sinew did you use? Which animal did the sinew come from? How long were the sinew fibers?

When you use too hot glue when sinewing it can damage the sinew, maybe this is the reason?

Better luck with the next bow!

JJ

I wonder if some sinew hasn't actually started to rot a bit before it is fully dry. Particularly larger tendons from Elk or Moose.
I had some moose sinew of questionable best before date and it was definitely far weaker than a quick dried deer tendon.

I did pickup some moose legs that had been out for some month, they did smell :) but ones dry the bow shoot.

for next time using the tepeliks:
allow one week.
fasten the ropes each day a bit tighter.
leave the bow on the tepeliks overnight.
dont go on if you notice a weak spot in the limbs, tiller / add sinew first.
as Redhorse says bending is easier earlier (less than 6 months) but this will probably weaken the bow. Adam Karpowicz did measure +10% efficiency afaik, with longer seasoning.

Redhorse wrote:

Throw away those tepliks :)
Heat the bow 50 celsius, bend it over knee to C shape.
Make a bowpress heat and put on a string, leave it with string rest of the day. Heat some and draw half, let it cool. If you lose much reflex, heat it and reflex it to C shape.
A hornbow has to be temper just like steel :)

Does anyone else brace the bow this way? It sure seems a lot safer. Perhaps a heat-assisted brace, then a "timar" process to regain some of the lost reflex?

Wow, sorry for you about the break. :(

Looks like you are learning a ton and should have some great successes on a few in the works.

I'm going to see if I can get a local machine shop to make me a bit like that. There is a place that made carbide tip for me for making arrows.

The only sinew I have ever used is rear leg elk sinew. At no time did the sinew ever appear spoiled. One concern would be if I over pounded the sinew during the shredding process. I used 6" to 12" long bundles, in three layers in the exact overlapping pattern that Adam shows in his book. I used a scale and split up the bundles to help apply even amounts of sinew. Next time I will try putting more sinew on the sal area. For this broken bow I only put on 77 grams of sinew.

I have enough leg sinew for one more bow. Next I think I would like to try some back sinew as from what I have read it might be easier to process.

Gaur, good luck with the router bit, the only positive item about this current bow is that the horn appears to have held very well with the matching joinery to the core.

To everyone that has replied with advice, thank you very much, I appreciate all of your time, with everyone?s help I will someday finish a composite horn bow.

Thats a real shame.
My first bow broke identically to that. Absolutely the same. Also when bending on teplics.

my first 2 bows were not finished and 2 next broke
:D normal learning curve

After re reading the entirety of your posts, here is my conclusion. The first bow is definitely broken because of glue starvation. I would encourage everyone who wants to build a horn bow to make a glue up sample of core wood and horn scrap. Practice the Korean method of building up 15 to 20 layers of thin glue as the material and experience the squeeze out. Try reheating the assembled sample for more squeeze out.

The second bow I would describe as a catastrophic limb failure triggered by core failure. Since all three have broken at one place, the evidence is confusing. But the break on the core seems diagnostic. It was fully supported when it failed.

There seems to have been excessive attention paid to matching grooving and much of the core material is tied up in this grooving. Is sugar maple a preferred species?

There is still half a bow to do experiments on. I would not pass up this opportunity.

I was just chatting with atarn member Gaur about the router bit grooving tool I had made. There is some concern that 2mm grooves are too deep and sacrifice too much material. I believe in Adam's book he recommends 2mm deep grooves. For the most recent broken bow the horn was 4mm thick throughout, I then grooved the core and horn. The horn and wood core meshed together very well, I then shaped the sal area down to 8mm which should equal horn that measures 2 - 4mm thick and hard maple measuring 4 - 6mm thick. The sinew measured approx 2mm at the break.

If I were to order a second custom router bit I would try less deep grooves, maybe 1.25mm deep. Ok moving forward for the next bow I plan on applying more sinew, and I think I will use 5mm horn for the sal. I also have a better understanding on using the tepeliks and giving the bow time to accept more bending.

Jack you are correct I do still have half of the bow left for testing, is there anything in particular that I should try?

Your grooving is OK at 2mm, actually it becomes difficult to use the matching-grooves method at less than that. For thinner horn, the depth of grooving would have to be less, or use non-matching, shallow cut grooves with the same tool.

When looking again at your cores - the ones with horn before sinew and the broken bow, it seems to me your real problem is insuffiicent and incorrect thickness taper in the sals. Again, the sals are the thinnest right below kasans, not in the middle or close to grip. Only this way the sal will bend evenly in an even arc with the stresses spread out well along the sals. Note the sals are even width, so the taper is essential and I suppose can be said to be elliptical. The usual bow mechanics still apply. The taper is cut in the core before sinewing.

Even in flight bows with longer siyahs the sals are thinner farther from the grip than in your bow. At both ends of the taper, the limbs' thickness grows more rapidly towards the grip and towards the kasan (where the core's section becomes triangular).

Uli mentioned to watch how the limbs bend and stop immediately if something looks suspicious. I bet you saw the limb showing a start of a hinge before the break. It is actually very easy to see in sinewed bows, where the sinew layer become excessively white as the glue cracks. At this point one simply stops, and either scrapes the horn to get the proper taper, or plays with heat to open the stiff sections of the bow - both to reduce the stress at the hinge.

Good luck next time

Adam

Adam, thanks for your thoughts, you are correct, when I shaped the sal before sinew the entire sal area measured approx 8mm, as seen in the below picture. After appling the sinew I did acheive a very small amount of taper but clearly not enough.

How many mm of thickness taper should I aim for? Should I start at 8mm at the handle and end up at 6mm at the kasan eye, or would I be better to start with maybe 12mm at the handle and end up at 8mm at the kasan eye. And more importanintly the taper should come from the core not in only in the sinew?

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The core is tapered, not sinew. As to the mm differences - I would go with 2.5mm taper from 8.5 to 6mm on this bow and 3mm thick sinew. That way the bow will be weaker, but there is less stress in the limbs. You will need more flex in the limbs with such massive (and curved) siyahs. Actually, you could even make siyahs shorter by another inch and have longer sals.

Adam

Adam & Others:

I am getting ready to bend some more cores. I would like to try and take your advice from your last post about the sal & kasan lenghts. The first two pictures are of my existing form and the bow core shape that the form produces. The last picture show my new proposed core shape per your advice of shorting the kasan by one inch and lenghting the sal by one inch.

Existing bow core form. This is the same form I used for the above failed bow except I flatten the kasan section per advice.
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Note: bow tips have approx 2" extra lenght which is cut off later.
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White paper shows proposed core shape.
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It is a good plan for a safer bow. The tips (3" or less) actually start at the apex of the tip/kasan transition, not above it, so the loop of string rests there and the string does not touch the kasan. Then comes the 6" kasan below. I suggest to round the kasan eye section a little (greater radius), so it will be easier to tiller the bow later on.

Adam

I have again drawn up another form template. If the tip starts at the apex of the tip/kasan transition I can see where I had very long tips, kasan section and a very short sal on my past bow atempts. Also on my above post the paper template it now looks to me that the kasan section is more like only 5" with 4" tips.

On the below picture I have moved back the tip and increased the kasan eye angle just a little. Should I now shrink the kasan area some more and or add to the sal, I am trying to hold the bow to 44"?

Edit: Did I go the wrong way on the kasan eye angle? If I smooth out the angle the other way it would look to me that the sal would make a smooth undefined transition into the kasan.

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Angle and radius of bending are two different things. I was talking about the radius to be greater, not about the angle to be sharper.

Adam

Adam, thanks for taking the time to help me understand. I got out my protractor and drew in some circles with increasing radius'. I again made up some paper forms all based from the previous wooden form. In the first paper form from above I redued the lenght of the kasan but now with shortening the tip and lengthening the sal the kasan is back to the same as on the wooden form. It seems that I really only shortened the tip and lengthened the sal by one inch. Back to your original comment should I shorten the kasan some more and if so where should I add length to? I would still like to hold the bow to 44".

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Note the bottom edge of the tape on the tips marks where they will get cut off. Also note that tips on the wooden core have opened up very slightly as you can never expect the wood to hold 100% of the bend.
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Yes, you can re-use the form you have, but I would still increase the radius of the kasan eye. Then, when you carve the kasan, make sure it is no more than 6 inches. Bear in mind the apex of the bend does not need to be exacly at the end of kasan. The kasan ridge can end above the bend - then the limb will straighten at the bend when the bow is drawn (or be tillered with heat to straighten). It helps to reduce stresses in the bow.

Adam

Adam thanks again for the marathon coaching. I brought the kasan eye radius from 3 7/8" up to 7". I added a small paper shim to follow the new kasan line into the sal as seen below.

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After some time off I have started working on the next composite bow revision. I again ordered more green hard sugar maple this spring and had much success boiling and bending several core sections. Below is the joined core that I will attempt my next bow on. You can see I have marked on the tips where the nocks will be placed; the bow will measure 44" nock to nock. Note I could leave the tips longer if this would provide any stability or performance benefit. I also have increased the sal lenght by an inch over previous bows. The kasan/tip transition measures 14mm thick and tips measure 15mm. Next I will begin preparing more horn.

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It looks good to me now. I plan on making some more forms soon - mine need the angle of kasan reducing.

Yesterday I was able to get some more shop time in. I started with preparing two horn strips from raw horns. I was able to make quick work with the use of a band saw and table top belt sander. I then used my custom router bit and jigs to groove the horn. The finished horns measure 19.5 inches long, they are 5mm thick at the tips, 4mm in the sal area and then tapper down to 3mm. I also was able to groove the core as well. The router bit works very well but I had to make a new jig for the core as the core shape did not match up with the last bow I was working on. For me that still is better and grooving by hand. 3 hours start to finish for the horns and approx 1 hour to build the core jig and all of 2 minutes to mill grooves. I then went right to applying 1% glue to the core and horns. I will plan on applying 20 coats.

To be fair I first practiced milling grooves with some scrap material and in the past have destroyed a set of good horns as part of the learning curve. I have an addendum log to Adam's great book that I have been keeping for this entire composite bow project. Both are invaluable to me.

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The grooves look very nice and this is a good option if one plans on making many bows. I machine cut grooves for a couple of bows years ago, but was very worried about the potential burnishing of the wood and horn, which could interfere with adhesion later.

Adam

Adam, but did you actually encounter this problem? I am also contemplating using a router bit...

I have not used a router bit, but toothed blades mounted on a moulding head - the type used with a table saw. There were slight marks from burnishing on the wood, these would be hard to see on horn. Perhaps the burnishing can be avoided with router bits made of carbide.

Adam

Yes the router bit I am using has a carbide cutting edge. I would guess there is an optimal router speed and material movement speed, both of which I paid no attention to. I don?t think any of the material showed signs of burnishing but I have some scrap material that I will examine tonight, what should I be looking for; I would guess I am looking for polished shinny surfaces? If the router bit does burnish the material could you follow up by cleaning the grooves with a matching grooved scraper, ect?

This brings me back to why deviate from what worked back hundreds of years ago? For me I found great difficulty in grooving the horn by hand, this was followed up by the horn delaminating, note this was probably from very poor glue sizing and less due to the poor grooving. To eliminate the problems I moved to using the router bit and applying 20 coats of 1% glue.

I will report back after examining the scrap material.

Using a magnifying glass I examined the router made grooves and then added and examined some handmade grooving. I could not tell if the wood or horn was burnished. I could tell that the router bit leaves a very clean crisp edge but I don?t know if this will be a problem. Time will tell. I am hopeful that I will have the bow done and curing by mid September.

Over the last three days I applied 20 coats of 2% glue. I let the core and horns dry for the last day and now tonight I glued the horn and core. I used 100% fish bladder glue at 30%. While the glue was warming up I used three halogen lights to warm up the horn and core, I also was boiling a pot of water in the work room to bring up the temperature and humidity, the room was at 84F. When the glue was ready I quickly applied a heavy coat of glue on the core and horn. I quickly clamped the horn using C clamps with a leather backed strip of blocks to help apply even pressure. This was followed up with the second horn. I had no problem with glue gelling before I was done clamping.

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bheggeseth wrote:

Over the last three days I applied 20 coats of 2% glue. I let the core and horns dry for the last day and now tonight I glued the horn and core. I used 100% fish bladder glue at 30%.

Great job! Thanks for the pictures.
Did you use fish bladder glue also for the 20 coats of 2% glue?

I have always used 100% fish bladder glue for my attempted composite bows, mostly because I wanted to remove as many unknown variables as possible. Fish bladder glue is the first natural glue that I have used, only recently did I make some sinew glue and found out that I have been spoiled. I was surprised how much quicker the sinew glue gelled. Note strength test showed the sinew glue was real close to the fish bladder glue. I am hoping to use the sinew glue for a 48? Native American ash sinew gull wing bow.

I spent some time over this weekend and have shaped the two most recent bows I am working on. Both have approx the same dimensions. The horn extends into the kasan and ends just before the tip transition. The horn is 5mm thick at the handle, 4mm for most of the sal and then reduces down to 3mm for the kasan. I am using Adam's advice for the sal thickness dimensions. At the start of the sal the thickness measures 8.5mm and then the sal tapers down to 6mm. From here the core thickens into the kasan. Currently the width of the sal only tapers 3mm. Note the full dimensions are listed below, I am open to all suggestions so please share your thoughts. I will need to spend a few days preparing sinew so there is time for any corrections.

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It has taken me several weeks but I finally have the sinew ready. I am using rear elk leg sinew and it is quite time consuming to process, I figure 20 to 25 hours. Also I would be curious as to how much waste sinew everybody generates. For 100 grams of sinew I ended up with 150 grams of scrap, note it is not really waste as I can use if to make sinew glue.

Now for the bow, it is shaped to the dimensions listed in the above post. I am open to suggestions for the amount of sinew to use and how it should be divided. For this bow I though I would use all 100 grams split into three layers as seen below. As for the 250 gram core weight I think it is heavier due to the horn extending right up to the tips. My last core shared similar dimensions and came in at 200 grams.

All advice is welcome, I hope to get the first sinew layer applied this week followed with a week of drying in-between each additional layer.

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I think this looks extremely promising :)

I have not measured the amount of scrap, but I have a feeling that I don't end up with as much waste. The reason is probably that I tend to use shorter fibres for the first layer.

I am also experiencing a lot of scrap, processing deer sinews.

Do you guys separate the sinew fibers by hand, or do you employ some sort of automation?

I think I could make a bow out of what you are throwing away. Mostly the outer sheath is useful in Elk.

So I have applied the first layer of sinew which covered the handle and the outer edges of the sal, ending just at the transition to the kasan. Once the glue gelled I pulled in 12 inches of reflex as described in Adam's book. My concern is the un-evenness of the bending. This is the third bow that I have applied sinew to and but the previous bows have never looked this uneven. Prior to the sinew each bow limb was shaped to the same dimensions.

My question is should I reduce some horn on the right limb to get the sal bending to match the left limb or do I just keep adding sinew and fix this with final tillering? It seems as the sal/kasan transition on the right is where all of the bending going on. Where as on the left the entire sal is bending nicely.

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Arry wrote:

I am also experiencing a lot of scrap, processing deer sinews.

Do you guys separate the sinew fibers by hand, or do you employ some sort of automation?

As far as I figured out, that depends how your setup looks and how much force you use further in the process. I have an old piece of train track as my anvil, usually I open up the dried sinew with a few stronger strokes with a standard hammer, and then switch to this after breaking up the stratum fibrosum (?): http://www.mehr-als-werkzeug.de/product ... uepfel.htm

When I started pounding the sinew, I made the mistake of using too much force *and* hitting the sinew with the sharp sides of the hammer, plus pounding the sinew not thoroughly enough (so that smaller parts weren't soft enough). As I tore it down, the fibers where damaged from the edges of the hammer, also there were parts of it who were still slightly stiff. So lots of scraps. Yesterday I worked through some older pieces that I had prepared some time ago and the comparision with sinew that I took more time to pound with the wooden mallet was striking.

Also there's this to consider: http://de.wikipedia.org/wiki/Sehnenscheide

In Adam's book, he writes that he tries to remove as much tissue from the sinew as possible before drying, so that's probably the stratum fibrosum? I have no idea if they remove that part before drying, but when working the deer leg sinew, there's much of a parchment-like part, that will mostly be scrap if there's not a few strands of sinew stuck to it. It almost looks good, but it's trash.

Texture is everything. I also scrape stiff pieces over the back of a knife pulling with one hand and holding the sinew between the knife back and thumb with the other. Several strokes limbers up the strand.

Use the end of a wood block instead of an anvil. Only pound the whole sinew. Soften well by hammering before breaking up into strands. Rotating the sinew while pounding helps to break down the sinew.

I use the back of a scissors on stiff strands of sinew to soften them up as well. I have questioned if I am pounding the sinew too much and thus causing all of the waste, but any less pounding and I just cannot process as the tendons are just too hard. I have wondered if other types of sinew process more easy. I have been tempted to try some back sinew.

Also how short of pieces can you use? I separate the sinew into three lengths, the shortest bundle is at least 6" long. Any less than that and the sinew goes into the scrap pile. Also a lot of scrap is due to me trying to break down the sinew into even thin strands. Often I start with longer strands but then try to thin them down one last time and then they split into short strands or become uneven in thickness that need further processing which again results in too short strands.

For the moment this thread has split into too topics. Going back to by previous question about the uneven limbs. I will be applying the second layer of sinew after the weekend and am wondering if I should do some tillering on the stiff limb now or wait until after the sinew is applied and cured.

Any advice before then would be great.

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Just a thought (something to check):
Wouldn't it be safer to tie the two ends with a string, than using these vices?
It may happen that the ends are not tied to the top board at the same angle (or with the same force). Has the bow stayed in this vice for a long time?

I did play around with the clamps and they are not to blame. In fact I tried to pull the stiff limb into bending but it did not help. On my last bow I used clamps to hold the bow while I applied sinew only to have the bow fall off halfway through applying sinew. So for this bow I have set several pins in the jig board. I drilled two small holes in each tip and then I was able to set the bow tips on the pins. After I applied sinew I was able to simply pull the tips into the next set of pins. The clamps are only on loosely. Once all the sinew is applied and dry I will probally wire up the tips and wait for the bow to cure.

From what I have been reading about this issue other places here on the forum, I think the general advice would be to continue and adjust the limbs once the bow is cured. If you made sure the limbs had the same thickness before applying the sinew, I can't see how it could turn out to be a problem. The assymmetry does not seem to be too much.

Looks like it's going to be a pretty bow!

Here is how the bow looks after the second layer of sinew. I was giving this some thought and is it possible that the stiffer limb we become the weaker limb in the end because it will have less recurve dried in?

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Third and last layer of sinew just applied. In all there is 100 grams of sinew and approx 80 grams of glue. My goal is to let the bow cure for 3 months. On the past two bows after they had cured I removed sinew until the bow dimensions where symmetrical and matched my design template, then from there I went ahead and started opening up the bow and begin tillering. Of course both bows failed during this process.

One question I have is with the uneven bow shape as I fear the right sal is much stiffer. My thought would be to even up most of the bow so it is symmetrical and aligns with my design template, but to leave any uneven thickness in the sals alone until I start opening up the bow and begin tillering.

Outside of waiting for the bow to cure I have several self bows to concentrate on. Also I have been studying how to cook up some bow varnish. Unless I come up with some questions about the varnish I will leave everyone alone here for awhile. Thanks again for all of the help each of you have provided me.

Last, I wish everyone a happy new year, I look forward to seeing all of the new work from everyone in 2013!

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Now that the sinew has dried some I noticed some large air bubbles under the sinew. Not sure if this was the right thing to do but using a rasp I filed off the sinew until I reached the air pockets. There was probably a 4 inch long by 1/4 inch section of sinew that just did not seem to bond with the previous layer of sinew and had several air pockets. I would guess that one of the bundles of sinew just did not get applied correctly.

A quick search on the forum and it looks like keeping the bow core, sinew, and glue all hot helps prevent air pockets. These are all things that I have done every time I have applied sinew and previously I have never had any problems.

I have now since re- applied a new layer of sinew to build back the section that I have rasped off.

Just as I figure out one problem I seem to find a new one...

I too had this problem. my way to solve it: at one end of the bubble pierce a small hole with a needle, heat up the area and fill in hot glue on the opposite end with an injectionsyringe. you can see how the bubble disappears. then press the area down (clamp, etc.) and let it dry.

repeat if necessary, until the finish is fine.

I've had this as well, and always at places of high reflex.

I have fixed this as well with a syringe and hot glue. I like to use very concentrated glue in this case.

It has been a few weeks since I have finished applying sinew, I believe this time there are no bad air pockets under the sinew. Today I have smoothed out any rough spots and re-tied the bow tips. The bow currently weights 336 grams and to me looks like a real turkish bow core. Part of me wants to let it cure forever as in it current state one can only assume it will make a fine bow. The other part of me will be soon ready to tiller and find out what went right and wrong. Key improvements over the last bows are matched horn grooves and proper glue sizing, along with a better sal taper from the handle to the kasan eye.

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Cool 8) I can relate to that dual feeling, hehe.

It looks promising with all that reflex. 8) Before opening it up, I think I would consider wrapping the kasan eye on at least the right limb. With so much reflex in a spot there should be plenty of shear-forces wanting to pull the horn and sinew apart from eachother.

The bow has now been drying for 3 months and I feel it is time to try and open it up. My humidity gauge has been reading 50-55% for the last few weeks which I believe is high enough to start. As you can see in the picture I have started opening up the bow, my plan this time is to slowly over the next 7 to 14 days open the bow up until the tips are parallel, the whole time keeping pressure on the bow.

Is there any reason to let the bow rest during the opening process? Also allready the one limb is stiffer than the other, does this to be addressed now or if it can wait until further in the tillering process? Last, in an earlier post Kviljo recommended wrapping the kasan eye with sinew, does anyone have additional thoughts on this?

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Thanks, Brad.

From a stability point of veiw I would probably be concentrating on reducing the reflex at the kasan eye as much as possible.
Good luck!

I am not too experienced but is it really necessary to be so scientific in the approach to bow building after all DID the the medievel Turks etc really wiegh thier materials and measured everything to the nearest mm. I personally think that sometimes to much thought can go into a project to no real benefit. Dont get me wrong i am not critisising just stating an opinion. Keep up the good work.

The problem modern bowyers have is that they do not have the years of training and experience that the traditional bow makers of the past did. On Thomas Duvernay's videos of the Korean bowyer, he does with an adze by eye what a modern craftsman would do with a mechanical thicknesser and a micrometer. It is misleading to think that because people used simple tools that they were not careful and precise. Karpowicz points out in his book on Ottoman bow making that the human eye can detect very fine variations in thickness and straightness.

This precision of size and proportions refers of course to a particular bow. Within a given type of bow there can be many variations and they produce bows of different draw weights, efficiency and performance. Some of the comments on this forum are directed at a particular problem that experience has shown can occur under the circumstances in a given post. They may only be true for that instance or they may be valid generally.

I understand where you are coming from as i am a old school joiner/carpenter, and can see and feel the differences in the materials i use, and appreciate that the bows were made with primitive tools using the eyes and touch to gauge the perfection of the product they were crafting(not just bows). But every piece of material used in the construction of a bow must have its own unique properties wether it is the type of core timber used, horn type or sinew, they are all organic materials so should not really be assumed to have a fixed type of physical property where one can give dimensions, weight and amounts to.
I think it must be all in the tactile feeling and maybe educated guesswork that will produce a good/bad project. My opinion only

My free time is limited, add the cost of materials and the time duration of building a bow, I believe using a scientific approach lends its well to forums, books, and manuals.

The measurements are to keep things in the correct proportions, ensure even tapers and come somewhere close to an intended draw weight.
Horn bows aren't really like a wooden bow where you start out with something that is well over intended draw weight and you reduce until it's the weight you want. With a hornbow you have limited material that can be removed eg. horn. So if you want to make a bow within certain weight parameters then yes you do really need to know the measurements that will get you close. Of course once you have made many bows you will devolp the eye and feel to do able to do it without - as with many crafts.
I think it's a very good idea when making your first few hornbows to be as accurate as possible and pay as much attention as possible to the details. After all you can make a very good wooden bow in a couple of hours if needed.....but you certainly can't make a hornbow in a couple of hours so experimentation is a slow process.

Not too much progress to share, I am slowly opening up the bow, depending on how the bow opens up I may need to add some heat in-order to get symmetrical linbs. I will plan on checking back in once I am ready to put the teplics on as that is when the last bow broke.

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Looks perfect! What kind of a glue did you use for the sinews?

I used fish bladder glue through out for the entire bow. My though is to first build a working bow with proven traditional materials.

As for the bow looking perfect time will tell. This is my third bow that has made to to the opening/tillering process, the first two had various problems and ended in failure.

Perhaps you should not overstress it too much? I think the glue should be quite white or blond, then it is at its best, if it is too brown or dark brown, especially what comes to hide glues, the glue might have other issues. The best hide glues should have light brown colour. Fish bladder glue seems to be very light in colour.

I have the bow opened up quite well and am looking for any warning advice before I move forward. The bow has seasoned for approx 5 months and while at the same time I have been opening up the bow slowly for the last 1 month. I am being very careful in my comments about this bow but I do feel that for this bow it feels "good" and seems to bend correctly. The last bows where ridiculously stiff and rigid.

In the below picture you can see the opened position with the asa gezi in place. I show this because on the last bow it seems that I was forcing too much bending near the grip with the tepelik.

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I have started to bend the limbs over the tepeliks, this is a very nervous process for me as the last bow snapped while bending over the tepeliks. As you can see on the pictures below I have a little more room to go on the tepeliks. Then I am not sure if I should used sharper shaped tepeliks and repeat the process or if the bow is ready to bend against my knees and attempt to string the bow.

Before any of this I will need to open up the kasan eyes. In the below pictures I have placed a second bow which came from the same forms. I am amazed at how much the sinew pulled in the kasan eyes. I would be afraid to remove any material in the kasan eye area and will plan on using heat.With using heat how close to the pre-sinew kasan eye should I work towards?

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One more picture with the asa gezi in place along side the "sister" bow core. The kasan eyes look better but still need to open more???

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For those who are viewing thanks for following all of my baby steps. Today I tried to open up the kasan eyes with some heat. I wrapped the sals and kasan with a dry towel and then proceeded to heat only the kasan eye section on the horn side over a oven burner. For the heating cycles I would slowly waive the bow over the burner for approx 3 min, I felt the bow was heated well enough once I could feel the sinew side warming by using the back side of my wrist as a temp gauge, as for the horn as long as I could still touch the horn I figured it is not over 50 celsius. From here I would apply pressure on kasan eye by further opening the bow while pressing the kasan eye against the floor. The problem that seems to be occurring is that the sal closest to the kasan eye is "opening" instead of the kasan eye.

My question, do I reduce material or apply more forcefull bending and heat. Is what I don't know yet is how much further the kasan eye will straighten out at full draw. My fear is that I can straighten/weaken the kasan eye too early in the tillering and once I get to full tiller the kasan eye flexes too much or worse breaks, as the thinest part of the bow is located right at the beginning of the kasan eye. Any thoughts?


If you compare the below picture with the one posted above you can see how the additional opening is now comming mostly from the end of the sal area and not the kasan eye.
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I would suggest using more heat/longer heating time to really straighten out the kasan eyes. My earlier bows definately suffered from too thick and inflexible kasan eyes with too much reflex.
I would be very careful with that outer part of the sal on the right hand limb. Keep checking it for any set.

Slowly heating out some more kasan eye reflex. Is it enough?

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This looks very promising.

sal-to-kasan angle at kasan eye in original bow is
35? measured along the back between
kasan back - and - tangent to sal

Bow should looks like before snewing, wait for a while in asa gezi. Do not rush for tepelik.

Cem

When bending the bow on the tepeliks is it common to hear small cracking sounds?

Yes, the glue inbetween the sinew might make small cracking sounds. They are ok, but be sure to check for delamination between the horn and core, or even between the sinew layers.

Looking good....fingers crossed for you!

Slowly making progress. The picture does not show it but I think that I have the kasan eyes to open up. When I pull on the bow tips the kasan eye opens up to almost flat before the sal starts to bend open.

My next step I think will be to try and get a string on the bow. If anything in the picture looks troubling please let me know. Thank you.

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This is exciting. Good luck, and more pictures please!

Another picture update. My thoughts for moving forward is to make a correct string for the bow with proper loops that follows along the sides of the tip and then come together at the kasan transition. Right now I am using two timber hitch knots which causes the string to lay on the centerline of the tips and I am afraid that the string will flip off of the tips and cause the bow to reverse. How much do I increase the brace height before I begin drawing the bow? Should any of the string be touching the belly side of the tips?

If you have any concerns from what you can see please let me know. This is getting close...

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Yes I too would be making a string of the correct length!
From a stability point of view it will help a lot.
The string should not be touching the kasans at all, just the base of the tip with of course the loops long enough to be running down the sides of the tips.
An endless loop string is easy to make so if the first one is a little long/short then it is easy to make the adjustment needed for the next one to be the correct length.

Just looking at your picture again and the limbs look very thin compared to the kasans. What are the thicknesses of both?

After the handle fades the sals run from approx 10.5mm down to 8mm at the kasan eyes, with an even tapper. As for the kansans do I have some room to reduce them? They are 18mm at their thickest.

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Over the weekend I built an endless string jig and by the second string I think I got the length right. In the below picture the bow is braced at 7 inches. One question I have is how deep can I cut the nocks? I am afraid that the string is going to slip out of the nocks. Mike and others, thanks for your most recent replies.

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Congratulations! very fine shape!

Peter

top. congratulations.

note:
brace height of original bow = 18cm
string nock of original bow = up to 8mm deep + 8mm long

top. congratulations.

note:
brace height of original bow = 18cm
string nock of original bow = up to 8mm deep + 8mm long

Thank you all for the comments, it might be too early for congratulations as I still have to tiller the bow out to a full draw, but this one is looking promising. As for the string nock I think I might cut it in a little deeper. Any suggestions on how much to reduce the kasans?

It looks great! You can without problem cut the nocks a little deeper. The original ones were rather deep I think, and then "filled in" with leather. What I might change a little, is the belly of the tips. The cross section should be almost like a triangle, with a narrow edge along the belly. However, be somewhat careful if doing to, as you should be sure to have enough sinew over the kasan/tip bend to reduce it without risk of straightening it out again.

I think it looks like you could reduce the kasans quite a lot. They look thick enough to only need just a slight amount of horn, at least from the middle and out.

full thickness of kasan area including leather cover and decoration is about
13 mm at kasan eye and 16-18 mm at tip base

so in principle your kasan has original dimensions but is overbuilt for a bow that has only 8mm thickness at kasan eye (which is the thinnest point of the limb)

:wink:

It might be time to retire this thread, As I continue to work on tillering I am fighting a twist in the limb. When the bow is unstrung everything appears aligned but after stringing the bow it is if uneven thicknesses in the left limb is causing the limb to twist as the bow is drawn back. I have tried to reduce some material on the edge of the offending sal which did not help but may have caused a hinge, or at least induced some set.

I currently have the bow tillered to just over 20" of draw which is shown in the below picture, the bow feels light, I simply just removed too much material. In light of my 4 year quest to make a horn bow that has been filled with mistakes, failures, and lessons learned I might be ready to set this bow down. I have made a "cheat sheet" of notes for each step of construction and now have added a few for tillering as well.

Thank you all for helping answer all of my questions. I just received in 10 pair of horn from Thailand and am ready to start the next round of bows.

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I spent just a little bit more time and got the tiller up to 26", there is a noticeable hinge on the limb with the twist. At 26" the bow pulls 30 pounds. This bow is underweight and will probably not hold up very long but I am ready to call this beginner's project a success.

More bows to come, thank you all.

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Congratulations on your bow. I really like the shape. Whatever the flaws might be, I think a working hornbow is a substantial success. Plus, your thread is full of useful information.

I'd call that a success too! The bending section is short, but at some 30 pounds, I think it should be fine. As long as it does not delaminate or twist too much. I've had too short sals on mine, and the horn have started to break down with white compression marks across the limbs, but they still shoot. (although not so often...)

Great to hear that there are more to come! It's nice to follow these buildalongs.

I'd still say that bow was a success for you Brad. I'm sure you learned a ton from the process and I look forward to seeing the next 10 ;).