Main Discussion Area > Horn Bows
My horn bow build-a-long
DC:
When I was bending it to measure the string the crack in the horn extended itself about 2". The part that I had previously CA'ed is still fine. The crack continued straight down the bow so I CA'ed the new part. But,,, right where the new section of crack is the limb now has a sideways dogleg that I'm pretty sure wasn't there before. I've been watching for twist because I was proud of myself for not having any. This doesn't look like twist, it looks like a sideways bend. But I guess it could be twisting. I'm trying to get rid of it by heating the eye.
DC:
I got the twist/ sideways bend corrected with heat so I tried to brace it this morning. The left limb went into full bend and the right limb went into full reflex, so it was "S" shaped. The rubber band would have held it I think but it was such a delicate balancing act. If I straightened the left limb by squeezing the limb and the string it would pop through and the right limb would go full bend and the left would go into reflex. This is obviously not right. Maybe not enough brace height? I didn't have enough hands to measure it while I was playing with it but I took notice of where it was and it was about 8". That's in the ballpark according to Adam. It's like each limb is ready to oil can and any push will send it one way or the other. I'm pretty sure the left is the weakest. I was planning on resinewing but now this is happening. Not sure if I want to mess with it until I get an idea of why it's flopping back and forth.
JNystrom:
If you cant stop the excessive bend by hand, its quite apparent that the tiller is off then. You shouldn't run into this kind of problem if you let it be freely on the peg board and it stays balanced. Is your peg board 100% symmetrical?
Try to have the pegs as far on the tips as possible to mimic being braced with the bowstring.
DC:
Peg board is symmetrical. It doesn't do it on the pegboard. The pegs are right in the tip bend and I think there is enough friction to stop it. It happens as soon as put the tension on the string and remove a peg. I've been looking at videos of people shooting hornbows and to me it looks like all/most of the bend occurs in the inner portion of the sal. The outer part of the limb never seems to go past straight. Mine does(this goes back to your earlier comments) and that gives the limbs the opportunity to "oil can". Mine is bending more like a conventional bow. I've been looking for progressive pictures of drawing a hornbow but haven't found any yet. I think if I stiffen the outer sal/ inner kasan eye area I think it would solve the problem but that would entail putting thickness where no one seems to put thickness. The only thing I can think of is that the combination of leverage and thickness make the inner part of the sal weaker but still thicker so the limb still has taper along it's length.
PS I just looked at a picture in Adams book and it looks like the whole sal bends evenly right out to the kasan eye which doesn't quite straighten out at FD. Now I'm thinking that when I made this I wasn't really sure where the eye was. I put reflex in the sal rather than the eye. So now the eye is bending too much. I'm stripping out the last of my long sinew so I'd better get this right.
DC:
OK here's the new kasan ridges. The dark line is shadow. It's a nice smooth blend.
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