Construction of my first horn bow (not going well so far)
So recently I just started building my first Turkish horn bow. I got my bending forms made and decided that I would try and use some of the hard maple that I had laying around I'm my garage for the past few years. unfortunately its kiln dried but I figured I would give it a shot.
First attempt:
at first I tried what I have seen countless people on here doing. I cut the wood into strips 20mm thick 2 inches wide and 30 inches long and soaked it in water for two weeks. I then boiled them for an hour and finally tried to bend them, which failed horribly. I believe that they broke because they were not hot enough and obviously kiln dried.
Second attempt:
I decided I would give it a second shot with the kiln dried wood because up until yesterday I couldn't find a source for green maple. this time I cut the pieces thinner at about 14mm. then according to some carpenters I know I only soaked it for a week( they said that two weeks was way too long, and could weaken the wood) and then I tried steaming them in a home made steam box. I steamed them for 45 minutes and then got them onto the forms as fas as possible to bend them. this time I almost got them to bend but they both developed cracks in the bend between the tip and kasan.
so now I'm moving on to my third attempt, but first I need to order some green hard maple as there isn't any trees to cut down in southern California.
also how does my bending form look, are the angles ok?
First attempt:
at first I tried what I have seen countless people on here doing. I cut the wood into strips 20mm thick 2 inches wide and 30 inches long and soaked it in water for two weeks. I then boiled them for an hour and finally tried to bend them, which failed horribly. I believe that they broke because they were not hot enough and obviously kiln dried.
Second attempt:
I decided I would give it a second shot with the kiln dried wood because up until yesterday I couldn't find a source for green maple. this time I cut the pieces thinner at about 14mm. then according to some carpenters I know I only soaked it for a week( they said that two weeks was way too long, and could weaken the wood) and then I tried steaming them in a home made steam box. I steamed them for 45 minutes and then got them onto the forms as fas as possible to bend them. this time I almost got them to bend but they both developed cracks in the bend between the tip and kasan.
so now I'm moving on to my third attempt, but first I need to order some green hard maple as there isn't any trees to cut down in southern California.
also how does my bending form look, are the angles ok?
I'm not the expert here, but I think your form will make a bow that looks quite like my last one, with a very sharp sal/kasan bend. It may be better and more representative to give it a larger radius at this place. Also, I think it may be good to give both the sal and kasan at least a very slight reflex.
If you round the inner curve of the kasan/siyah bend and slightly round the sharp outer corners of the billet, you might be able to bend it without cracking. You don't need all the width at that place anyway, and you may also go down a little in thickness at the bend, and build it up with some extra sinew. I had a lot of troubles with kiln dried maple. It really can not compare to the green wood. Bending boiled green maple is just amazing :shock:
If you round the inner curve of the kasan/siyah bend and slightly round the sharp outer corners of the billet, you might be able to bend it without cracking. You don't need all the width at that place anyway, and you may also go down a little in thickness at the bend, and build it up with some extra sinew. I had a lot of troubles with kiln dried maple. It really can not compare to the green wood. Bending boiled green maple is just amazing :shock:
I also not too successful with steam bending but I d support Kviljos tip to reduce the wood thickness and build up a kasan sinew ridge
+ or try naturally grown siyahs
..btw a chinese manuscript describes the making of the siyahs as a "rate-limiting" step of bowmaking: trainees were judged by the number of ears thy could produce in one day
:wink:
+ or try naturally grown siyahs
..btw a chinese manuscript describes the making of the siyahs as a "rate-limiting" step of bowmaking: trainees were judged by the number of ears thy could produce in one day
:wink:
luckily I'm not a Chinese trainee :lol:
I will have to try rounding the outside edges next time. about the form I tried to make the angles a bit more well angular because I'm afraid of how much spring-back I will get from the wood. I just bent those pieces that cracked yesterday and have yet to take them off the form to see how much they will spring-back on me.
besides that will such a sharp angle in the Sal/kasan area cause me problems later? or would it be advantages for me to smooth that bend out a bit? what about the kasan/tip bend should I make that a bit more gentle as well?
One more question I was to reduce the thickness in the tip/kasan bend and then later build it up with more sinew would I loose any strength or rigidity? wouldn't it also make the tips heaver and thus slow the bow down somewhat?
Update:
I just pulled the wood off of the form, it looks as though the bends failed because of too much tension along the outside edge while bending. so I think along with green wood I need better bending straps.
I will have to try rounding the outside edges next time. about the form I tried to make the angles a bit more well angular because I'm afraid of how much spring-back I will get from the wood. I just bent those pieces that cracked yesterday and have yet to take them off the form to see how much they will spring-back on me.
besides that will such a sharp angle in the Sal/kasan area cause me problems later? or would it be advantages for me to smooth that bend out a bit? what about the kasan/tip bend should I make that a bit more gentle as well?
One more question I was to reduce the thickness in the tip/kasan bend and then later build it up with more sinew would I loose any strength or rigidity? wouldn't it also make the tips heaver and thus slow the bow down somewhat?
Update:
I just pulled the wood off of the form, it looks as though the bends failed because of too much tension along the outside edge while bending. so I think along with green wood I need better bending straps.
When bending with a metal strap you need to make sure the strap is tight before you even start the bend. Having it slightly slack and not taking over any tension until the bend is started lets the wood fibers start taking on tension strain when they're not equipped to deal with it.
People getting fixated on that second bend seems to be causing a lot of trouble with first time builders.
A more continuous bend Korean style limb seems like a better compromise.
People getting fixated on that second bend seems to be causing a lot of trouble with first time builders.
A more continuous bend Korean style limb seems like a better compromise.
Have a closer look to the break: you haven?t followed the growthrings at the belly of the siyah. The best way to succeed in bending siyahs is to follow the growthrings at the back- and the belly- side of the wood.
Michael
Michael
Had some free time today, so I took a look at my forms. I ended up softening both bends some; the kasan/sal bend more-so than the kasan/tip bend. I also redesigned my bending straps so they should take most if not all of the tension of the bend next time. now I'm just waiting for my nice green wood to get here.
the sharper the kasan-tip bend, the less stacking (at least in theory) as the drawing force is optimally conducted when the angle between string and tip is 90? (i.e. during some point of draw). so: long draw - steeper kasan-tip bend (compare for example turk vs tatar or korean design)
the sharper the sal-kasan bend the higher the risk that the bowstring can slip off the string bridge upon release.
the overall angle of sal-to-tip rarely exceeds 90?.
regarding physics, the wood always fails on the outside as its less resilient to tension (outside) than to compression (inside). the solution is sinew backing or steel strap.
a triangular sinew ridge is very stable and not too heavy in my opinion.
plus you still can correct that bow part with heat if you want.
good luck !!
the sharper the sal-kasan bend the higher the risk that the bowstring can slip off the string bridge upon release.
the overall angle of sal-to-tip rarely exceeds 90?.
regarding physics, the wood always fails on the outside as its less resilient to tension (outside) than to compression (inside). the solution is sinew backing or steel strap.
a triangular sinew ridge is very stable and not too heavy in my opinion.
plus you still can correct that bow part with heat if you want.
good luck !!
Not strictly true that the wood is failing in tension first It's actually "failing" in compression just to get bent in the first place.
The metal strap just allows all the failure to occur in compression.
The metal strap just allows all the failure to occur in compression.
Uli, i am shure you mean 90? between string and kasanend, not tip.
hm.. actually I mean the overall angle covered by the whole siyah, i.e. what is stiff and does not bend, so : from last part of sal until tip/nock - at brace.Kyudohund wrote:
Uli, i am shure you mean 90? between string and kasanend, not tip.
so only "tatar" and "crab" bows typically have more than 90? (outside) / 270? (inside) here, would you agree ?
Apparently a missunderstanding. Typical for turkish bow is an angle about 90? between kasanend and string at full draw. This has the best leverage effect.
Agreed.Patrick Menzies wrote:
Not strictly true that the wood is failing in tension first It's actually "failing" in compression just to get bent in the first place.
The metal strap just allows all the failure to occur in compression.
You should drill some holes in the end of the metal strap and screw it to the wooden form (tip end!), then bend the strap to a sharp 90 deg. bend so that the core 'slots' in nicely. Once the tip end is inserted you then need to clamp the strap to the wood (needs to clear end of form). This way as soon as you bend the wood the strap is doing all the tension work.
I too have had some trouble getting the maple to bend without cracking. All of the problems I had with bending were tension failures. I found that by reducing some material on the inside of the kasan/tip bend that the material under compression now better equaled the material under tension. This reduced most of the cracking/splitting.
Most importantly I build a new tray to boil the core strips in and added more heat to boil with. With this new set up I am able to get a rolling boil under the entire length of the core strips. I was able to bend 5/8" (16mm) thick hard maple and red mulberry without using any kind of metal strip and could simply put one clamp at the end, as seen below.
[external image]
[external image]
[external image]
Most importantly I build a new tray to boil the core strips in and added more heat to boil with. With this new set up I am able to get a rolling boil under the entire length of the core strips. I was able to bend 5/8" (16mm) thick hard maple and red mulberry without using any kind of metal strip and could simply put one clamp at the end, as seen below.
[external image]
![[external image]](http://i334.photobucket.com/albums/m426/bheggeseth/turkish%20bow/bend.jpg){kind=link}
[external image]
![[external image]](http://i334.photobucket.com/albums/m426/bheggeseth/turkish%20bow/boil-1.jpg){kind=link}
[external image]
![[external image]](http://i334.photobucket.com/albums/m426/bheggeseth/turkish%20bow/mulberry_bend-1.jpg){kind=link}
From my experience, you can only bend very dry (not that green anymore) wood at extreme angles at a 1 cm thickness. Anything beyond that is problematic.
Mulberry is indeed the best. I was able to harvest it myself and bend it at a very extreme angle at 2 cm thickness.
I would give your kiln dried maple another shot at 1 cm thickness. However I strongly recommend harvesting your own maple and mulberry lathes from nature to ensure maximum greeness at bending abilities at 2 cm thickness.
Hope this helps.
Mulberry is indeed the best. I was able to harvest it myself and bend it at a very extreme angle at 2 cm thickness.
I would give your kiln dried maple another shot at 1 cm thickness. However I strongly recommend harvesting your own maple and mulberry lathes from nature to ensure maximum greeness at bending abilities at 2 cm thickness.
Hope this helps.
just finished my newest attempt and everything went really well. this time I got a hold of some green maple that had been cut only about a month ago. I cut it into lathes that were 16mm thick and soaked it for two days, then steamed it. it bent without a problem. now I have two extra lathes soaking that I will bend in a few days. I figure I will leave the ones I just bent on their forms for at least a few days and then remove them and bind the with rope to hold their shape while they dry for a few months. I will continue to update as I make more progress thanks to everyone that helped thus far.