Primitive Archer
Main Discussion Area => Bows => Topic started by: Mo_coon-catcher on August 21, 2015, 08:42:47 pm
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I've got a bow that the tip snapped on. I'm working on fixing it by cutting off the tip in a v-splice and am going to put a new end on. I'm doing the same to the other side to make it match. I plan to steam the joint and clamp it together for a tighter fit. If I'm going to steam it in wondering how tigt of a fit the joint needs to be before steaming. I have one at the point I think will work. When held up to the light it has about 30% contact withot pinching it tighter and with finsger pressure it closes to about 80%. I'll probably use a clear epoxy to glue it then once it's cleaned up I'll glue a patch of rawhide on top to help it hold.
Any opinions on if this will hold up and work. I feel like it will. But I've bever made a splice before and I'm doing two on this bow so all tips apreciated.
Thanks,
Kyle
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My guess is that if the fit is not perfect it will depend on the glue used. I would use smooth-on or urac.
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It will hold with a good hard glue but wrapping it will work far better than rawhide.
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For wrapping, which would be better a strong thread or sinew?
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Strong thread and epoxy. Not primitive but more sure-fire in a non primitive scenario.
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In this case I would rather be a better chance of working and holding up. I've got several spools of fly tying thread which to me seems pretty strong for its size compared to cotton threads. Will that be strong enough you think? If I use smooth on I'll need to order it so if I need a stronger thread I can get it at the same time.
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Coming from a fly tier, several types of fly tying thread are silk. I if using fly silk I would look for fly rod builder's epoxy. It is designed to work with encasing the silk. It's is very hard and and very weather proof. But me personally I am a sinew fan. Applied wet it will get tighter as it cures. JMO Patrick
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Like the guys said, if you take nylon thread and bind it on around the splice as tightly as possible, this will go A LONG way toward stabilising the splice. You can apply glue before or after binding depending on the viscosity of the glue. Superglue is actually great for this type of thing assuming it isn't going to bend. Hide glue is great too. You can use just about any string you want assuming it is strong. You can even cut strips of thin rawhide, soak it in hide glue and bind it on if you want to go primitive. Or sinew for that matter. It'll be way stronger than it was before, but be careful not to overdue it or the tips will start weighing too much.
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Keep working it until you see no light and you won't need to wrap it ;)
I've done a few bows with spliced in tips and they don't need wrapping. A good v-splice is very strong.
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Fine.... I'll be the one to say it... ahem, pics?
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I never took a pic before starting the fix. But this is the point I was at the other day. Because of my affinity to make tips as small as possible there isn't a lot of material to work with. Especially since I wanted to get as close as I can without damaging the skins. Since being glued down with TB3 I have no idea how to safetly remove them. And because of that I opted to not steam the tips to get the joit tighter. I was able to get the joint tigh enough to not see light through it for about 90% but couldn't get any tighter. Which I did get that joint tighter than what's in the picture. An couldn't quite get rid of a little curvature to the mating sufaces. Something I need to practice on I guess. So I opted to glue with a slow set epoxy and plan to wrap. I looked at the smooth on epoxy, but can't afford it for the probability that this the only time for a while it'll get used and only for a small amount too. Especially since I read that it has a short shelf life even in the fridge. I replaced the tips with a less dense wood so I'm hoping that it will help compensate for the added mass of the glues. I went ahead and glued due to a lack of time to work on it. If this doesn't hold I'll clean it up and put more time in to get the joints tight.
Kyle
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Thats not much gluing surface area told the stresses. Im worried. If you leave it like that, undo that wrap and gpue on an underlay to help distribute the load over a wider surface. Make the underlay functional too like brush nocks. Next time you need to do that make it a deeper longer splice. I understand you had limited space. Glue on an underlay to help, it will save that. Make it long. I mean like the inches past the splice tip. Make it come to the tip also. Then do your wrap if you want but you wont need to. Use locktite gell if the joint is good, tight bond III if its not a perfect match.
Trust me, it will look amazing.
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I havnt wrapped yet, I'm giving the epoxy a full day before I shape it down. I was thinking since I'm going to do an overlay anyway about extending the overlay to the end of the joint . I'll probably do your suggestion of and underlay. Removing the old wrap doesn't bother me at all. I planned to when I go to wrap the new on. I feel like between all that it should hold.
Kyle
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Would be great to know how thinks work out after ya shoot bunch of arras. Good luck!
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Sleek, I think I'll use that idea on it. I took me a moment to get exactly what you said. Reading comprehension a not quite there while at work. Using my buddies large table belt sander it won't take any time to get the tips, long under and overlays flattened. I think if I pick the wood well for complimenting colors it'll look good. The wood I put on the tips is black cherry and the bow is black locust. The woods I have to put on are ERC, more cherry, walnut, hickory, ash, black locust, osage.
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Erc is light and compression strong.... it may work. Unfortunately it also splits easy. Pick a wood that doesnt split well. If you want I can draw you a pic or better yet, post a pic of an underlay I did....
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After reading a couple times I think I have a pretty good picture. Though I'd still like to see a pic. I'm thinking like you are on ERC for the belly and was thinking since the draw is only #40 that walnut wouldn't be bad for the back. Getting a sort of cosmopolitan look. Like this molle I did this spring.
Kyle
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Yup, like that. Though I think you ment Neapolitan...
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(http://i1092.photobucket.com/albums/i411/rocketernally/20150730_203623_zpsiu6xrpbw.jpg) (http://s1092.photobucket.com/user/rocketernally/media/20150730_203623_zpsiu6xrpbw.jpg.html)
Like this only larger....
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And I turned the wood so its grain is 90 degrees to the bow wood. Makes it even stronger...
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(http://i1092.photobucket.com/albums/i411/rocketernally/20150730_075653_zps2xrq69j5.jpg) (http://s1092.photobucket.com/user/rocketernally/media/20150730_075653_zps2xrq69j5.jpg.html)
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Yup, that's the word I was after. That's exactly what I was picturing. I like the carving on the tip. I think if I use the lighter woods I can get some fancy stuff going on and not add substantial mass.
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There is virtually no stress at the tips that's why we can make them like 1/4 inch wide and them not snap off. You don't need an underlay or wrapping. Your joint looks good so I wouldn't stress over it :) One of the bows I did this on was a static recurve of 69# - no wrap, no problems and it has plenty of reflex and the recurves are close to 90 degs.
The picture you put up with the underlay of erc sure looks pretty but you I bet it wouldn't bend even without it. When you make a molly like that the lever only needs to be 1/8th thicker than the end of the working limb to not bend. Think about a working limb that has a stiff spot and how little wood you need to remove to make it work. Double the width to double draw weight but only an increase of an 1/8th of total thickness to double draw weight.
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Mike, I agree with most of what you say but I dont think it applies to the forces a splice is under. A splice is under torsion stress and without enough surface area absorbing ( read distributing ) the stress over a large enough area, the stress will concentrate in one spot and the joint will fail. There is for a fact a minimum amount of surface area a joint must have per a set amount of stress or the joint will for a fact fail. More glueing surface area equates to less pounds of force per unit of surface area. His joint hasnt the needed surface area in my opinion ( I cant quantify that its just experience, my own, however lacking that may be compared to others ) and is likely to fail. Increasing the surface area to distibute the torsion forces into an underlay which converts the torsion force into a compression and tension, reduces joint stress and allows for better chances of survivability.
The thickness of the joint in this situation, aside from allowing surface area for glue, doesnt matter. Yes, he needs it not to bend, because working splices are much more difficult, and for certain he probably has enough thickness to prevent bending. Beyond that thickness ist a factor. The factors here that are most important are distibution of stresses and trapping that splice over an underlay.
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Mike, I got lots of respect for you, I sure hope you dont view my reply as anything except as an explanation of why I understand what I know to be true, and not an attack on your own statements.
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If the bow was going to stay in my hands when finished I would see how well it would hold on its own. Just because is going to someone else I want to remove all chances I can of breaking. That molle was working good on its own before te underlay, it was completely to add a color contrast. I will say that I'm learning a lot
Kyle
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Mike, I got lots of respect for you, I sure hope you dont view my reply as anything except as an explanation of why I understand what I know to be true, and not an attack on your own statements.
Not even slightly ;) and thank you for being so polite.
I like a good debate better than i like most other things, if people can't disagree and discuss those disagreements with mutual respect then there is little point to these forums in my eyes.
I still think it would be fine without an underlay purely because i've done it myself a few times now. The stresses at a straight limbed bows tips are very small. I'll see if I can find that recurve I mentioned before and show you some pics.
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(http://i492.photobucket.com/albums/rr283/mikekeswick/010_1.jpg) (http://s492.photobucket.com/user/mikekeswick/media/010_1.jpg.html)
(http://i492.photobucket.com/albums/rr283/mikekeswick/009_1.jpg) (http://s492.photobucket.com/user/mikekeswick/media/009_1.jpg.html)
(http://i492.photobucket.com/albums/rr283/mikekeswick/008_1.jpg) (http://s492.photobucket.com/user/mikekeswick/media/008_1.jpg.html)
(http://i492.photobucket.com/albums/rr283/mikekeswick/007_1.jpg) (http://s492.photobucket.com/user/mikekeswick/media/007_1.jpg.html)
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That's awesome. I think I need to work on my joint to make them even conpareable with yours. Does it seem like there is much strain on the joint? How long is you joint? Mine came out to right about 2". I'm not sure if that's quite enough to hold or not on its own. I'll eat to go any further until I get some opinions. Until then I'm going to start making the over and underlays incase that's te route I go. And if it makes much difference I did carve them at a bit of an angle to help align the string with the handle. Probably a half inch or so. The other side looks almost identical to the side in the pic. Sorry if it's a little hard to see. I can take another if I need to.
Kyle
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Two inches is actually a bit more than four on a V-Splice, ...which is nubbins close to not quite enough in my opinion. I'd certainly thread and epoxy wrap it, which is probably as strong or stronger than the overlays/underlays idea. It's insurance in any case, but I'd be likely to do it myself especially if I was sending the bow off to someone else.
OneBow
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Its not enough. You need to over and or underlay. You do not want a limb tip hitting you in the face.
Mike, your limb tips are recurved, which reduce torque on the joint because the linear distance between joints and tip is shorter than if the limb is straight, like on Kyle's. His has more leverage than yours and looks to be shorter of a splice. Its no good without reinforcing.
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That's what I was thinking. So m glad I already got the over and underlays started on. I'll work on getting them close tonite. I started on some white ash overlays that'll run from just past the tip of the joint and turn into the string holding overlay. And some ERC underlays taht will be about 2" past the joint and I'll featherdown thin enough to flex a little then run it to the tip.
Kyle
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Actually sleek the levers on a molly act basically the same as a recurve, mechanically speaking, while his splice is a tad short it will prolly work but when it's going to a new home best to be safe, i make my vee splices 3-4" long giving 6-8" of glueing surface
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Thats a good length bubby.
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I finally got the time to get the splices finished. I went with cherry for the main piece, white ash for the ovetlay, and ERC for the belly piece. I tried going with just the over and underlays but at about 28" of draw the thin ends of the black locust started to split. Once I found that that was where the pop came from I filled it with super glue and clamped it shut. Then I wrapped it with fly tying thread and soaked it in super glue. After that it held great and shot the way it did before. I think it looks better than it did before with all the colors. There is some handshock but it's not unbearable and it still has decent cast.
Kyle