My horn bow build-a-long

[DC]

Step?
I got a bit of shaping done today. Narrowed and thinned. I don't want to thin the sals until I've finished the kasans and tips so I've got something to hang on to in the vice. The horn is about 4mm thick, I hope that's right. The Book is kind of vague about how thick the various parts should be. It's hard to shape a bow like this when you've never seen one. Pictures just don't work that well if you only have a couple of views. I spent most of the day searching the net looking for pictures of the kasan, eye and tips. Are Groziers bows fairly good copies, most of the web pics are from his site?

[DC]

Bit of a setback today. I was reducing the width of the tips. I had about 3/8" of wood to take off i couldn't reach it with the bandsaw because of the awkward shape so I thought I would use a hand saw. I got about an inch into the cut and realised that a rasp would be the better tool. I started rasping looking for the saw kerf to know when to stop. Never saw it go by . So I epoxied a piece on to repair it. Once it's all shaped the piece will only be about 1/16" or less thick so I'm sure it won't be a problem.

[DC]

I was looking at my trial core wondering if I can use it for a bow. It is flawless except for this knot. If I made the limb 24mm wide it would go right through the centre of the knot on the belly. Where it appeared on the back would depend on how much core I used. If I made it 22mm wide it would almost disappear except for a wiggle in the grain. The core is the same shape as the one I'm working on so a little heat would straighten out the kasan eye bend. You can see where it is by the handle "V" joint. What do you think? If this was any other bow I wouldn't think twice or even once about it.

[DC]

Is this very roughly the shape I'm looking for at the tip/kasan bend? This is on the trial form.

[bownarra]

The knot makes it completely unuseable. Don't kid yourself into thinking it will work - it won't! It isn't just the knot it is the swirly grain that accompanies it that is also a complete no-no! This is the wooden bow making experience talking! Go back to beginner status and just follow what the book says word for word You need a different mindset making hornbows. Literally every single thing must be perfect....or else that house of cards starts wobbling.
Your shape is sort of right but you do not want the grooves on the belly at the base of the tip. The tip should be triangular and the string simply sits on the side of the triangle.
Yes a step from the width of the kasan  into the width of the tip. Don't blend/fade this area make it a step down in width.
I'll try and get a good picture of the tip.
No Grozers aren't really what I would copy.
You can get many pictures from the bows in the Topaki Palace collection.

[DC]

Thanks bownarra I wouldn't be this far along without your help, much appreciated
I tried a search for the Topkapi Palace collection but I'm not having any luck finding pictures of bows. Do you have a link that might get me there?

I'll continue using the knotty core for practice. So the kasan should be a sort of triangle with the point to the back and the tip should be a triangle with the point to the belly. JWB bows has a short video about carving this. He scoops the sides of the kasan. I read somewhere that this isn't necessary on a light bow. I would have thought that it would be preferable on a light bow to bring the tip weight down. What's your opinion on this?
Thanks again
Don

[JNystrom]

Here is couple of pictures i took just couple of weeks ago. These are from Istanbul military museum, topkapi didn't have these angles to take pictures from. Actually its prohibited to film there but...

If you google "mandarinmansion turkish bow" you will find Peter Dekker's page that has a lot of close up pictures of good turkish bows.

[DC]

Thanks JNystrom I'll take a look.

I have more questions. This will be my last chance to get the horn to an even thickness. Is anyone willing to take a shot at horn and wood thickness for a 40-45# bow. the bow is 120 cm NTN, tip is 8 cm, kasan is 20 cm measured at the apex of the eye bend. Limbs are 24mm wide. At the moment the horn is about 4 mm thick. I think it should be closer to 3 mm but I don't know. I'm wondering if I shouldn't make the wood a bit on the thin side as I can reduce the horn on an assembled bow but I won't be able to get to the wood. The Book says the 3 parts should be about equal thickness which would put the sinew at 2 mm but The Book says I should go with 3 mm. Again, I can reduce the sinew if there is too much. Is it possible to reduce the draw weight on a completed bow? I'm concerned that this thing is going to be too heavy and be totally useless to me.

[sleek]

Thanks JNystrom I'll take a look.

I have more questions. This will be my last chance to get the horn to an even thickness. Is anyone willing to take a shot at horn and wood thickness for a 40-45# bow. the bow is 120 cm NTN, tip is 8 cm, kasan is 20 cm measured at the apex of the eye bend. Limbs are 24mm wide. At the moment the horn is about 4 mm thick. I think it should be closer to 3 mm but I don't know. I'm wondering if I shouldn't make the wood a bit on the thin side as I can reduce the horn on an assembled bow but I won't be able to get to the wood. The Book says the 3 parts should be about equal thickness which would put the sinew at 2 mm but The Book says I should go with 3 mm. Again, I can reduce the sinew if there is too much. Is it possible to reduce the draw weight on a completed bow? I'm concerned that this thing is going to be too heavy and be totally useless to me.

The ONLY help I can offer is to take it off your hands if it comes in overweight.

I have always enjoyed your posts and craftsmanship, so I'm looking forward to seeing this progress to completion.

[DC]

  so I'm looking forward to seeing this progress to completion.

So am I but boy it's tough at times. I've been close to packing it in at times just from the difficulty in finding out stuff. If it hadn't been for writing this build-a-long, I don't know. I've started reading so many of these things and have them fizzle out to nothing I vowed I would see this through make or break. I actually don't think the building is that tough, we'll see, but knowing what to do next is hard. The Book is supposed to have everything but it's buried. Once you figure out what to do all of a sudden it appears in The Book.
Sorry, Rant mode off.

[DC]

More practice on the trial core. I think I'm closer to the right shape. I must be getting close, the tip is starting to look very spindly.

[sleek]

How do those not have torque problems?

[DC]

I think they do. Very great care is taken to have no twist or string alignment issues.

[JNystrom]

Those dimensions that Adam gives in his book are just rough recommendations. If you use "too" thick horn, what are the worst things that could happen? The mass of the bow would be 20 grams too much, or little bit more unstable. As horn has less bend resistance than wood, there is really no fear of the bow coming overweight. With nice thickness horn of 4-5mm you have plenty of room for tillering and also the bow will hold reflex better.

Assuming the limbs are properly tapered and shape is nothing extreme, the sal thickness will tell you the final weight. 120cm #45 bow i would make the core about 8mm thickness in sal parts, 110cm #45 bow i would make 7mm. After this by giving the bow a plenty safe amount of sinew, 100g, would raise the thickness from 8mm -> 10mm and 7mm ->9mm.
These are just estimates, i haven't made a 45 pound bow yet.

I would throw that 1:1:1 rule to the dumbster. One reason is because the originals were done with 60 grams of sinew... There is a huge variation in the portions anyway, crab bows used couple of millimeters of horn, some turkish bows have even 8mm.

[DC]

i would make the core about 8mm thickness in sal parts,

Just the wood or is this wood+horn?