Primitive Archer
Main Discussion Area => Bows => Topic started by: sleek on October 23, 2017, 05:32:19 pm
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Its a wide loop string for a horse bow. Not every shot, but a few rimes on release the string jumps off after the arrow is shot. I have raised and lowered the brace height, shortened the loops, and still it happens.
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Pics please.
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Here you go
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Cut your string nock a little deeper and groove the sides of the nock so the string rides in the groove
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I will go deeper. The sides are grooved but I will go deeper with those too... thanks Pat.
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Definitely needs to have deeper nock grooves. Does it have bridges?
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Yes it has bridges. I just switched to a thinner string to see if that helped. I shot it a few times and the string jumped again. This time because its a thinner string is didnt leave tje nock, it just jumped the bridge. I think limb twist or tip alignment may be the lroblem.
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It could be limb timing too. Is there any hand shock?
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There is a small amount, but nothing that I would say isnt normal.
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Pic of the bridge?
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Here, they double as brush nocks as well.
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Those work great with perfect alignment and no torque but they encourage the string loop to slip past if things are even slightly off. A bridge that goes across with a groove in center encourages things to hit the center and stay there.
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Got any examples of something that would work?
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The nock doesn't nbeed to be any deeper, that isn't going to help.
The problem is either stability eg. limbs twisting or the angle that the string goes from the nock to the back of the limb/bridge.
Need to see it strung up, view from the tip looking along the tip/limb and a view of the tip from the side.
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More bridge width to guide the sting into line if its vibrating about.
Del
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I would alter the way the string sits in the nock slightly so that you don't have that curve leading up to the lip and you should have a good groove leading up to the groove of the bridge
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After some heat correction last night, i went and shot it today. The correction made no difference. It wasnt much of ine anyway, the tips were only slightly off. So taking Dels idea of vibration into account I went with a heavier arrow. That did the trick. This biw doesnt like light weight arrows. It doesnt like a 390 grain but likes a 430 grain. Heavier arrows tamed it down.
So, is that a limb timing thing, a quirky thing with the bow from its 7 inch long ( never doing that again ) levers, or something else?
Maybe it is a limb torque problem, and the heavier arrow allows the limbs to fix themselves before the string hits home. Or maybe the limbs have bad timing that I cant notice otherwise, and a heavier arrow stops the string from flopping sround on release?
Either way, the bow will get shot with a heavier arrow from now on.
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When you draw the bow does the string lift off both bridges at the same time?
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No, they dont. One siyah is bent at a different angle than the other. I didnt notice that until it was too late and had glued all the side and belly laminations on. But, I tillered the bow that way, and it doesnt rock in my hand with a loose grip when drawn. I tried to take that into account when tillering, but may have screwed it up anyways. So, its an asymetrical bow.
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I don't know if it means anything or not. I had one that lifted off unevenly during tillering but once I got the tiller looking good it had fixed itself. I just kind of assumed that with good tiller they would lift together. With one siyah being a different angle. Don't know. Maybe someone will.
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Sound like the string isn't hitting true on the brush nocks on the return.
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I meant bridges,something is out of line,
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Is the string coming off on the draw or the release?some can be lost in text!lolo!
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The string was jumping off after I shot the bow. The arrow would shoot, and the bow would eject the string. But now that I am shooting a heavier arrow there is no problem.
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Now you have to reverse engineer that and figure out why a heavy arrow works and a light arrow doesn't. You'll never reach 220fps with a heavy arrow ;D ;D ;D
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does the string loop 'merge' at the bridge?
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DC, I think Im just gonna leave it. This bow has been a project and I am calling it done. It really hits hard, so im calling it done. I wint be making anymore like that either. If I get a slow motion camera I may revist this but till then, ima let it throw arrows at a target.
Loon, the loops come togeather right before the bridge. Maybe 1/8 " before.
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Hint - look at a Turkish bows tip. :)
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If you hold the bow and string lightly as you let it down from full draw does the string come onto the bridges centrally?
Del
PS. I'm reluctant to call 'em "bridges" as I think they are more like grooves that true bridges which would IMO be wider.
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If you hold the bow and string lightly as you let it down from full draw does the string come onto the bridges centrally?
Del
PS. I'm reluctant to call 'em "bridges" as I think they are more like grooves that true bridges which would IMO be wider.
They do seem rather narrow for 'bridges'. I suspect that the culprit in the string ejection issue is the same thing that ill effects other very narrow bridges. I'm talking about rope bridges that span a gorge. Such bridges are plenty strong, but they tend to swing about a little wildly under a load. Often causing a trip or fall. I imagine you are correct in thinking the heavier arrows settle things down by slowing the speed of the string return.
I should say though, those brush nock/bridges look way more KEWL than the big clunky bridges I've often seen! Some bridges look like an apparatus of some kind has been clamped onto the bow limb. These are svelte, clean, and - dare I say it - Sleek!
OneBow