Primitive Archer
Main Discussion Area => Bows => Topic started by: Lefty8917 on April 10, 2015, 06:57:40 pm
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This is a 65" osage take down made from 2 billets. I used a 2 part epoxy and fiberglass cloth for the handle. The handle turned out great. It seems to be very strong and by bottom limb fits in like a glove. I have been floor tillering it for a few days now with no issues. Today I went to put pressure on it as if I were stringing the bow and the top limb (which has the handle connected) slipped up and the two pieces pulled appart. Creating an aweful cracking sound and the damage shown in the pictures. This is my first attempt at any form of a takedown bow. Am I missing anything? or did i do someting wrong? Can I still salvage a takedown bow from this or should I just epoxy it together and call it a day?
(http://i325.photobucket.com/albums/k386/lefty8917/IMG_3462_zpsg6opae6h.jpg)
(http://i325.photobucket.com/albums/k386/lefty8917/IMG_3464_zpsed1qz4ar.jpg)
(http://i325.photobucket.com/albums/k386/lefty8917/IMG_3461_zpsufo7rxt0.jpg)
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You can probably repair the cracks with good glue and clamps. I think I'd reinforce the FG sleeve at the open end. If that gives in the least it will probably happen again.
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Looks like the handle sleeve flexed, letting the angled end of the limb tilt to where the tip was the only part with strain on it.
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Holy cow man. . Sorry. . I got no fix for you but i feel your pain. ..
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Did you make the sleeve useing madcrows how to
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Bubby, I used a how-to by Brian Rose out of primitive archer mag. I really dont think I have any bend in the handle. The damage came from when the bottom limb was slipping out the the sleeve with pressure still applied. I believe I can use clamps and glue to fix it. The only thing I worry about is it slipping out again. Is there a special way to string this type of take down?
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Looks like your glass should have extended up the handle a bit farther. If you glue and clamp and then put a vertical kerf and insert in it should tie it all back together.
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well I usually have a suggestion for everything, I am stumped on this one,,since I have no experience with that design,, I would glue it together and shoot it,, :)
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Pat B, I think your suggestion to reinforce the open end of the sleeve is the way to go. Because, the FG did crack there on the belly side. So if I am correct, the FG probably failed there creating enough flex in the handle to push the bottom limb the rest of the way out. I will glue and clamp those cracks then wrap another layer or two of FG around that open end. I hope that will do it.
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I was standing beside him when it happened. Not a sound anybody wants to here. I think he will be able to salvage a takedown out of it, just part of the learning curve.
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Run thin superglue into the cracks and then clamp shut. Once dry very carefully remove any excess glue. Then get hold of some carbon woven cloth (like your glass) and add a few more wraps. The carbon is more flex resistant than the glass.
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Looks like the cutting angle is about 30°. Is it possible the limb comes slowly out of the sleeve when shooting? Maybe then the stress is located on a little point.
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Simson, are you saying I should have made the cutting angle a little steeper? I was trying to maximize the surface area where the two parts touched. You could be right though, maybe with a greater angle it would be less prone to wanting to pull apart. Thanks everyone for the input so far!
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Simson, are you saying I should have made the cutting angle a little steeper? I was trying to maximize the surface area where the two parts touched. You could be right though, maybe with a greater angle it would be less prone to wanting to pull apart. Thanks everyone for the input so far!
Yes that's my thought. If it is a glue joint I would go for a glue surface as long as possible. In this case I would go for a 45° angle to prevent tearing apart slowly after every shot. Of course the sleeve should be strong enough.
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I was trying to maximize the surface area where the two parts touched. You could be right though, maybe with a greater angle it would be less prone to wanting to pull apart.
The only reason to angle the ends is to make the limbs align when put together. There are more stable ways to do that.
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I was trying to maximize the surface area where the two parts touched. You could be right though, maybe with a greater angle it would be less prone to wanting to pull apart.
The only reason to angle the ends is to make the limbs align when put together. There are more stable ways to do that.
can you explain a few better methods?
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Lefty,
I've never used anything but a metal socket and ferrule system. These use a square joining cut (90 degree) and are completely stable. I'm no engineer, but it would seem that the angle cut (with maximized surface area) would be more helpful if gluing the limbs. I'm sure some here have experience with your fiberglass handle, but it would seem that the more angle cut beyond 90 degrees would contribute to slippage, but again I plead ignorance with your particular system.
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Lefty, I reread your thread. A few things you should do next time otherwise:
First, make the glued on socket on the lower limb – not upper like here.
Second, look at the damaged end. It couldn't hold together – just on that point were you have the most stress on the wood is an outrunning grain and obviously a big knot.
Third, cut the angle mirrorwise. To create pressure in direction of the belly not to the back. Hard to explain for me in English (not native), what I mean is:
look at the side of the bow, left back, right belly, upper limb upside. Now cut the angle from (right) belly down to (left) back. Not otherwise.
Hope this make sense for you.
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... what I mean is:
look at the side of the bow, left back, right belly, upper limb upside. Now cut the angle from (right) belly down to (left) back. Not otherwise.
Hope this make sense for you.
Either way the angle is made, one limb will have the tip of that angle taking forces in the wrong direction.
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Either way the angle is made, one limb will have the tip of that angle taking forces in the wrong direction.
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Jim, that is true, but when the lower limb is glued in the socket, the red line is right for cutting angle. The only direction not provocating delamination.
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Either way the angle is made, one limb will have the tip of that angle taking forces in the wrong direction.
Jim, that is true, but when the lower limb is glued in the socket, the red line is right for cutting angle. The only direction not provocating delamination.
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The article mentions this but it's fairly easy to see how people overlook this subtle difference.
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There are a series of how to videos on youtube made by a guy called Big Jim. Watch those videos if you want to know how to do this correctly.
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I just did one following the BIg Jim video as suggested by Mike.
I didn't saw the joint at an angle... I can't really see any point in it, and your pic illustrates the potential for failure.
Mind, I'd already sawed it straight anyway ::) :laugh:!
The write up of mine starts here...
http://bowyersdiary.blogspot.co.uk/2015/03/starting-take-down.html (http://bowyersdiary.blogspot.co.uk/2015/03/starting-take-down.html)
Maybe you can clean up the split/break. Splice on a short section and start again with a straight cut or a much more obtuse angle.
Del