Author Topic: Turkish learn-along  (Read 344 times)

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Offline MattZA

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Turkish learn-along
« on: October 10, 2019, 01:15:25 am »
Hi all,

I've started playing with a Turkish shaped horn bow build. Not having Adam's book, I've been working with information from various places across the internet and TBB series.

Being limited to very few materials and experience, I'm treating this as a learning curve and an experiment. I'm fully accepting that it may fail due to incorrect materials and mostly my building technique, but as I say, it's a learning curve for my next attempt.

I'm aiming for a Turkish shape bow, pulling anything up to 50# at 29". I've chosen to use vertical bamboo as the core, with Gemsbok horn on the belly. I'm waiting on a butcher I know to finish removing the sinews from three South African antelope. Two wildebeest (slightly smaller than an elk) and a single blesbok (about 25% bigger than a whitetail deer).

I'm sure I've broken every rule in the book so far, but here are a couple of photos. I've made a bit of progress since then, and have the horn glued on the entire belly. Next I'm going to glue my handle onto the back, shape the bow a little bit, and then start preparing the back for sinewing.

If you have any advice or questions please feel free to voice them. I'd very much like to get more discussion going on the building of these magnificent machines.

Matt
Unprofessional bowyer. Johannesburg, South Africa.

Offline MattZA

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Re: Turkish learn-along
« Reply #1 on: October 10, 2019, 01:19:41 am »
Here's a photo of the siyah being glued in. I opted to use Garapa wood. Despite it being a tropical wood, I've found it to bend well enough and to glue very well. It's very stiff, and slightly lighter than Osage.

I hand spliced the Vs, used self-made hide glue (and a little gelatin). There's a bit of a gap at the end, but the belly side of the splice will be covered in horn, and the back side will have a second strip of wood laminated over it to provide enough thickness and enough wood for me to shape the outer limbs.
Unprofessional bowyer. Johannesburg, South Africa.

Offline MattZA

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Re: Turkish learn-along
« Reply #2 on: October 10, 2019, 01:25:37 am »
Here's a quick picture of the core pre horn and sinew.

I'm assuming your first thought is that it's too thin at 3/8". I agree and am going to add a cut-to-shape laminate on the back from the beginning of the kasan.

The handle (white ash) is going to be glued on the back as well.

I'd love the thoughts/ideas of experienced horn bow makers here. Is it doable to build it like this?
Unprofessional bowyer. Johannesburg, South Africa.

Offline MattZA

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Re: Turkish learn-along
« Reply #3 on: October 10, 2019, 01:39:25 am »
The horn is another area I'd like to have a discussion about. Being the first time I used Gemsbok horn, I wasted an awful amount of it, but decided to use what I have. That way if it fails, I can see how and why it failed.

I had to use 3 pieces. The short piece is obviously at the handle, and the same length. The longer pieces have since been glued on and will reach the far end of the kasan by the time I finish feathering them out.

My major concern is width and thickness. There is a very slight taper in width of the strips, and they start about an inch wide. Also, instead of leaving the visible side of the horn in its natural crowned shape, I opted to sand a small flat section across the top of the crown to try and spread the load of force. This means my horn is probably only 3mm thick along the "de-crowned" crown.

Any advice here would be very much appreciated.
Unprofessional bowyer. Johannesburg, South Africa.

Offline bownarra

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Re: Turkish learn-along
« Reply #4 on: October 10, 2019, 01:42:57 am »
Possibly! But I suspect the core will fail. I use that boo in glass bows all the time and have seen how poor the glue joints are sometimes, they also don't use a great glue in the first place as the stuff is only meant to sit on the floor haha.
Good luck with your build.

Offline MattZA

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Re: Turkish learn-along
« Reply #5 on: October 10, 2019, 01:43:50 am »
And finally, this is just a photo of the wrapping that I used to put the horn on the belly. My experience with this is fascinating. Initially I thought it might not be as tight as traditional C-clamps, but boy did I learn a lesson there.

It's a good thing I've left the core 1 3/8" wide, because the wraps had no trouble crushing the edges of the core, leaving waves along the outer limbs that I'll shape off when I begin carving it.
Unprofessional bowyer. Johannesburg, South Africa.

Offline bownarra

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Re: Turkish learn-along
« Reply #6 on: October 10, 2019, 01:46:15 am »
It isn't that the hoen will fail more that gemsbok tend to be too narrow and thin. In a way it is better to cut them into narrow strips and then glue the strips in parallel on the belly. This way you waste a lot less and get better thickness to work with.
If you are going to use a section in the middle to 'lengthen' the strips then max length should be 3 inches. Any longer and the joint will be in a bending section. Any joint in a bending section will fail.
the horn only needs to go about half the length of the kasan.

Offline MattZA

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Re: Turkish learn-along
« Reply #7 on: October 10, 2019, 01:51:25 am »
Hi bownarra,

My immediate thought was the same as yours - the glue used is likely to fail - especially in the areas that have been steam bent.

Thus far though it's surprised me. The glue holding the pieces together still seems absolutely rock solid. I boiled an offcut for an hour to test the glue. I then bent it to see where it would break, and interestingly it survived a similar amount of force to an un-boiled sample (approximately the same force as maple). Interestingly, it also didn't show any signs of failing at the glue. It broke in tension like any other wood would.

Assuming I use a normal maple core next time, what kind of dimensions would you recommend I start with? By that I mean when it's still nothing more than a block of wood.
Unprofessional bowyer. Johannesburg, South Africa.

Offline DC

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Re: Turkish learn-along
« Reply #8 on: October 10, 2019, 10:21:52 am »
Hi Matt, good to see your post. One of the things that has surprised me about these bows is how thin they are. The jury is still out on how much DW mine will have but I was down to 6-7-8mm thick for both the horn and the wood. They are about 3mm each. At one point I got out my other set of horns thinking that I might be able to split then on the bandsaw and double my stash. I don't think they are quite thick enough. On the Fletchers Corner forum one of the guys uses Ostrich tendons. You might be able to find them there.
Vancouver Island
If you don't have any questions you must not be paying attention.

Offline MattZA

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Re: Turkish learn-along
« Reply #9 on: October 10, 2019, 11:49:26 pm »
Hi Don,

You're right about the thinness of them. I keep feeling like I'm just holding a backing strip or something ;D

Finding horn the right thickness and length and width is frustratingly tough. I've got another Gemsbok horn which is actually considerably larger than the one I used initially. Once I'm done with this bow one way or another I'll try and use that horn. The only issue is that it's a little bit twisted, which creates another issue altogether.

I was pondering something about horn strips. As bownarra said above, bends in joints tend to cause it to fail, so gluing my horn on in strips could be a slight issue. However, will it fail if it's applied in staggered strips? Think the brick-laying pattern of sinew, but with horn on the belly. I wonder...

In fact I've only ever used ostrich sinews. This bow will be the first time I use anything else. The only problem with ostrich sinew is that it's used everywhere as a dog treat - therefore can be very expensive. My butcher is taking forever to process the sinew he promised me, so I'm considering just biting the bullet and heading to the local pet store.
Unprofessional bowyer. Johannesburg, South Africa.

Offline bownarra

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Re: Turkish learn-along
« Reply #10 on: October 11, 2019, 01:35:16 am »
Ostrict sinew is greasy I wouldn't recommend it for hornbows.
I got some a year or two back and didn't like it. It also isn't as strong as leg sinew from heavier animals.

Offline DC

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Re: Turkish learn-along
« Reply #11 on: October 11, 2019, 10:27:14 am »

I was pondering something about horn strips. As bownarra said above, bends in joints tend to cause it to fail, so gluing my horn on in strips could be a slight issue. However, will it fail if it's applied in staggered strips? Think the brick-laying pattern of sinew, but with horn on the belly. I wonder...


I'm going to go out on limb here but I think bownarra was talking about butt joints in the horn in a bending area. I think it's Persian(maybe) bows that have two narrow strips of horn on each limb. Maybe they only had Gemsbok horn and it kept splitting on them ;D ;D ;D Piecing together a belly like bricks(if I'm following your thinking) would put butt joints in the bending area. I'm thinking it's like cracks in a self bow. Cracks along the length are not a big problem but cracks across are. If you are using two lengthwise strips you may be OK unless the bow is too narrow or the belly is even slightly crowned. Either may tend to separate the horn strips when you bend it. Remember, I'm speculating here, I don't have any more experience with these things than you do.
Vancouver Island
If you don't have any questions you must not be paying attention.

Offline MattZA

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Re: Turkish learn-along
« Reply #12 on: October 11, 2019, 12:20:54 pm »
Yea I think it was the Persians. I presume they used Ibex, which is essentially the same thing. As you say, they probably got frustrated with the damn things splitting ;D

As for the butt joints, that why I suggested them in a staggered pattern. That way when there's a joint between two strips lengthways down the bow, there's another strip alongside the joint that is a single piece. Therefore you'd perhaps have enough strength from the other strips to offset the weakness of the one joint. I'm picturing maybe four rows of horn. Each strip is a different length to the next to it.
Unprofessional bowyer. Johannesburg, South Africa.

Offline DC

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Re: Turkish learn-along
« Reply #13 on: October 11, 2019, 12:29:09 pm »
I don't think I'd trust it but what the hey. If you're willing to risk all the work. That may be the reason why everyone kind of slavishly follows the old ways. They're proven and no one wants to risk throwing all that work away trying new stuff.
Vancouver Island
If you don't have any questions you must not be paying attention.

Offline bownarra

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Re: Turkish learn-along
« Reply #14 on: October 13, 2019, 02:14:57 am »
Just get some water buffalo horn! There are millions of water buffalo :)
No your butting strips idea won't work. Only full length side by side strips will work. This was done because it is easy to get full length strips this way and the bow design was too wide for the available width on normal horns.
Any horn joint in the bending section WILL fail. A butt joint will last the longest but it will fail. The compression these bows take is incredible but that is with a solid horn :)