My horn bow build-a-long

[DC]

The teplics are the wrong shape. They should have a slightly tighter radius than the strung bow. Don't heat the sals there is no need whatsoever and you will reduce the performance too much. This is what I meant about breaking cores Don't bend the bow over them.
I'm sorry but I was going to take some pictures of my pegboard for you. All the other stuff i'm busy with kicked that thought out of my mind....I will definitely take some pics for you as soon as I get back in from my morning run.
You want the pegs to sit at or just past the kasan eye.

Thanks for the picks. 

I figured the tepliks were the wrong shape but how do you know ahead of time what the strung shape is going to be?

Don't bend the bow over what, the tepliks? I thought that's what they were for??

If I don't heat them, how do I get rid of the ugly bend.

I've had trouble understanding the tillering process with these bows.

So with the peg board you don't use tepliks at all and the kasan eye is the thinnest part of the limb?

Sorry for all the questions but this is the important part, right?

So if this was a peg board the pegs should be where the black dots are?

[bownarra]

Indeed.....you have hit the nail on the head with the teplics shape! I can dig out a pair I have used in the past and take some pictures. Another way is to scale up a picture of a strung bow of similar length to yours.
Yes I mean those teplics. That is what they are for but they must be the right shape or else you run a strong risk of breaking the core under the sinew.
I don't see what ugly bend you mean. There is nothing wrong with the unstrung shape. The sals will straighten with use. Do not heat them ever unless there is twist in them when the bow is strung/drawn. However it is unlikely that the bow will be twisted in the sals. Normally it is the kasan eye.
When I use the pegboard I simply bend the bow on it progressively further, checking for twist/weak spots as you go, until you can string it. Once strung any twist will be apparent. Correctly shaped teplics allow the bow to be strung for the first time with good control. If a new bow is twisted and the limbs out of balance the first time it is strung it will act like a living thing haha. The teplics get around this. I find now that I have done a few of these they are generally pretty close to good tiller the first time I bend them so the process tends to go easily enough. For my latest round of heavy bows I have made a press using a boat winch.
Right
And finally yes that would be about right for the peg positioning.
Good luck and ask away if you think I can help.

[gorazd]

I "tried" the shape of the tepelics ,..... bending the future core only  - same width and thickness of the bamboo core around it... around 5mm bamboo core

The core survived .... so there was no problem with  finished bow too during the first bending 

Indeed.....you have hit the nail on the head with the teplics shape! I can dig out a pair I have used in the past and take some pictures. Another way is to scale up a picture of a strung bow of similar length to yours.
Yes I mean those teplics. That is what they are for but they must be the right shape or else you run a strong risk of breaking the core under the sinew.
I don't see what ugly bend you mean. There is nothing wrong with the unstrung shape. The sals will straighten with use. Do not heat them ever unless there is twist in them when the bow is strung/drawn. However it is unlikely that the bow will be twisted in the sals. Normally it is the kasan eye.
When I use the pegboard I simply bend the bow on it progressively further, checking for twist/weak spots as you go, until you can string it. Once strung any twist will be apparent. Correctly shaped teplics allow the bow to be strung for the first time with good control. If a new bow is twisted and the limbs out of balance the first time it is strung it will act like a living thing haha. The teplics get around this. I find now that I have done a few of these they are generally pretty close to good tiller the first time I bend them so the process tends to go easily enough. For my latest round of heavy bows I have made a press using a boat winch.
Right
And finally yes that would be about right for the peg positioning.
Good luck and ask away if you think I can help.

[bownarra]

I "tried" the shape of the tepelics ,..... bending the future core only  - same width and thickness of the bamboo core around it... around 5mm bamboo core

The core survived .... so there was no problem with  finished bow too during the first bending 

Indeed.....you have hit the nail on the head with the teplics shape! I can dig out a pair I have used in the past and take some pictures. Another way is to scale up a picture of a strung bow of similar length to yours.
Yes I mean those teplics. That is what they are for but they must be the right shape or else you run a strong risk of breaking the core under the sinew.
I don't see what ugly bend you mean. There is nothing wrong with the unstrung shape. The sals will straighten with use. Do not heat them ever unless there is twist in them when the bow is strung/drawn. However it is unlikely that the bow will be twisted in the sals. Normally it is the kasan eye.
When I use the pegboard I simply bend the bow on it progressively further, checking for twist/weak spots as you go, until you can string it. Once strung any twist will be apparent. Correctly shaped teplics allow the bow to be strung for the first time with good control. If a new bow is twisted and the limbs out of balance the first time it is strung it will act like a living thing haha. The teplics get around this. I find now that I have done a few of these they are generally pretty close to good tiller the first time I bend them so the process tends to go easily enough. For my latest round of heavy bows I have made a press using a boat winch.
Right
And finally yes that would be about right for the peg positioning.
Good luck and ask away if you think I can help.

You could do it that way but only with a thin core or bamboo. Also when you add horn and sinew the taper rate will change and so the curve too.

[Deerhunter21]

question... how do you tiller a horn bow???

[DC]

So far so good. How does this look? How do I stop the bow from walking back and forth as I move each limb to the next peg? As I bend the limb the handle slides across the saddle. You can see where I clamped the block to stop that but it really didn't help. I also put a top on the saddle because I don't want this think loose in my shop. I have to put a 1" pipe on the limb to bend it. I really can't see me pulling this thing.

Also with this much tension I can't see any way this is going to twist. How can I tell if it wants to?

Should I be letting it sit like this for some length of time before bending it more?

Why do I feel like there is a bomb in my shop ready to go off?

[DC]

I shaped the saddle lid to match the top of the handle and that stopped the sideways movement.
I cleaned up the horn a bit and found a lengthwise crack. I can feel it with my fingernail. Is that it, am I finished? Or CA and continue? I'll check Adams trouble shooting section.

PS Adam says to use CA so I did that. I'll wait for your comments before I continue.

[bownarra]

Yes it does tend to feel like there is a bomb about to go off when tillering these bows haha!
You cannot judge the weight until you have a string on (or a lot of experience!). The extreme string tension is one of the reasons for better performance. High initial energy storage. This is what you can not do with wood. A fair amount will pull out once it is strung for a day or so and then you will be left with the true amount of 'tillered' reflex.
The crack isn't ideal because it appears to be angling through the limb not running back to belly. If it was a crack induced during drying they tend to be the later and not a problem. I personally don't like the look of your crack but all you can do is proceed with tillering and cross your fingers.....
Tiller-wise the left limb looks ok but the right has a weak spot out of the handle. Do not pull it further until you fix that. Limb strength relative to each other is something you will have to judge by feel until you have it strung. A 2nd cut file and 60 grit on a block is the way to go to sort the tiller.

[bownarra]

The left kasan eye also appears a little stiff. Check thicknesses relative to each other with calipers, if there is no difference in thickness heat the left eye and open further.
You may have no twist - if not do a little dance and congratulate yourself. It will certainly be apparent when strung if there is any.
Yes you can leave it on the pegboard for an hour or so before removing any material/moving onto the next step.

[DC]

Black arrow too weak? Red arrow too stiff? Is that where you mean. I'm having a tough time seeing them.
Do I tiller this like a wood bow as far as dealing with the weak spot. ie weaken the rest of the limb and then make the other limb match? Or do I just weaken the same spot on the other limb?

I'm not liking the way the crack is running off to one side although it does look like it's straightening out some. I think I heard it crack. I'll carry on


PS   I had taken it off the pegboard and like a fool I hadn't marked left or right. The holes in the tips are not symmetrical so I might sort it out that way. I'll mark them now.

PPS  It's -6C here and the RH in the shop is 35% before heating it up so I may take some time off until it's a little more humid.

[DC]

Adam suggests not tillering if the RH is below 30%. Does this suggest that things may go easier if you kept the bow in a controlled environment of 50-60% maybe even 70% for the tillering period?

[DC]

Just wondering, this is the bow at rest. Should it be further open? I thought there was mention somewhere that the tips should be 90° to the belly at this stage.

[bownarra]

Humidity that low is a dream to me! I wouldn't worry too much about the humidity but yes it is useful to keep it equilibrated at 50 - 60 rh.
The belly cracks can be caused by the sinew drying (it also shrinks laterally)but yours looks like it may have been there all along. Did you put the linen patches on the belly during curing? They do help but a bit late now.
Yes the weak spot id where you have marked.
Yes treat it like a wood bow regarding weak spots. Even material removal on the good limb and either side of the weak spot. It can be helpful to put a piece of paper/card under the bow on the pegboard , bend the bow and trace the outline onto the card. Make corrections then repeat. The card will help you spot the differences between corrections and compare one limb to the other easily.
Be careful with any weak spots as they can cause the core to break.

[bownarra]

And yes you should open it out with heat so the tips are pointing straight up when at rest. It's tricky at this point because the bow is still holding reflex,some of which it will lose by being tillered to full draw. Chicken or the egg?

[DC]

And yes you should open it out with heat so the tips are pointing straight up when at rest. It's tricky at this point because the bow is still holding reflex,some of which it will lose by being tillered to full draw. Chicken or the egg?

OK My plan is to heat it the red marks to 50c. I'm thinking it will make it easier to tiller as I won't have so much reflex, won't have to bend it so far.