Primitive Archer
Main Discussion Area => Bows => Topic started by: chessieboy on October 04, 2013, 01:29:48 pm
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I posted something in the flintknapping section by accident. But, I now having other problems. The bow is a BBI, it has a thin osage lam with another Ipe section for the handle. It's 62" t2t and around 1.25" wide til the end tapers. I'm having two problems. First I just started tillering, barely to low brace and noticed the handle delaming between the core and osage. Second I'm running out of Ipe to thin it. I started to narrow it but I'm looking for input.
Thanks Bill
(http://i195.photobucket.com/albums/z149/chessieboy/null_zps22776ce2.jpg) (http://s195.photobucket.com/user/chessieboy/media/null_zps22776ce2.jpg.html)
(http://i195.photobucket.com/albums/z149/chessieboy/null_zpsf35d2fe2.jpg) (http://s195.photobucket.com/user/chessieboy/media/null_zpsf35d2fe2.jpg.html)
(http://i195.photobucket.com/albums/z149/chessieboy/null_zpsb2c6673e.jpg) (http://s195.photobucket.com/user/chessieboy/media/null_zpsb2c6673e.jpg.html)
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You have good fades, my guess is the oils aren't letting the glue harden and stick. Round those belly edges nicely and you will knock some serious pounds off without narrowing the bow more.
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I agree with Pearlie. How'd you de-oil your Ipe?
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Can't really see in the photo the handle delaminating, but if it is, that is a bigger problem than the ipe belly running out. Your gonna wanna narrow the limbs if you are running out of belly, which is fine most of time with ipe. But it doesn't look dangerously thin to me or anything yet. If it gets too narrow it can contribute to set, but ipe is more tolerant usually to narrower profiles than other woods. As for the handle, if it pops off when the bow is braced or strung it can brake the bow. If you think you can pop it off or bandsaw it off and reglue, than that is the best option I think. One thing you can do as well is wrap the handle very tight in glue soaked linen string or the equivalent. But if I were you I would remove and reglue. Your tiller might be the cause of the handle coming off, if your limbs aren't working evenly and forcing too much stress in the middle. You can also just wrap the handle in tight cord until the bow is tillered, I used to do that with red oak board bows, as in the beginning of tillering your tiller might be putting a lot of stress in the middle of the handle if the limbs are not working enough, which a lot of time in the early stages of tiller they are not. I agree with pearl too, your fades look fine.
EDIT: I ment *narrower*
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I used acetone to degrease then scored lightly both surfaces. I used smooth on. As far as I can see the area in the fades ( 1.5-2") from where the handle is delaming is not moving at all. That being said the more I exercise the limbs the more the delam I notice. Do you guys think I can pop off the handle area with screw drivers, no bandsaw?
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I used acetone to degrease then scored lightly both surfaces. I used smooth on. As far as I can see the area in the fades ( 1.5-2") from where the handle is delaming is not moving at all. That being said the more I exercise the limbs the more the delam I notice. Do you guys think I can pop off the handle area with screw drivers, no bandsaw?
You might be able to, but it might take some slivers or chunks with it. Be careful. I would suggest heating it, but then you might weaken the glue bond between the boo and the ipe.
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anyone else score wood to wood joints? I think you get a better joint with flat surfaces, not just for bow building but general woodworking.
I think the oils may have been the culprit or a starved joint? was there excessive clamping pressure?
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That doesn't look like a glue problem to me. There does not appear to be sufficient belly thickness to support the handle design you implemented and it is flexing. You needed to either: 1) make the handle laminations longer and fade more gradually into the limbs, or 2) Make the belly thicker underneath the handle, or 3) insert a tapered powerlam over the handle and fade area. Number 1 may be your only option at this point.
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Acetone has oil in it. Denatured alcohol works better
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got the handle off. It was a glue problems. I must have either gotten wrong proportions or not mixed the glue enough. When I pulled the handle off the glue was still wet. 3 days later and after curing in my hot box.
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If it was still wet you didn't mix it sufficiently.
If you use Smooth On, it has excellent gap filling properties, so you definitely DO want to rough-up all gluing surfaces. I do it with a toothing plane blade and cu the grooves as deep as the blade will cut them.
I've only ever had one handle piece begin to let go, and the surfaces were smooth and Smooth On was the glue. Since then I've used the toothing plane blade and never had another problem... even on dips and handle pieces that bend.
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Did you mix it by weight or by volume? For another woodworking project i used a 1 hour epoxy and thought i was getting real fancy by breaking out the digital scale and weighing my epoxy parts precisely. a few days layer and my project was falling apart and the epoxy was only partially cured. Problem was the density of the parts are different so when i mixed by weight instead of volume (as mentioned by the directions once i finally read them) i didn't get the proper proportions... :-[ I even checked it out by looking at the msds and sure enough, i blew it. At least know i know the densities so i can use a scale if i want to do it right :)
I'm not an adhesives expert and i'm not trying to start a heated debate, but just because a glue is a gap filler doesn't mean that creating gaps makes it work better, or am i wrong here? I honestly don't know. I think a toothing plane is doing something a bit different than roughing it up though isn't it? on a toothing plane don't you create matching surfaces that mate together, so that on a small scale it is still flat mating surfaces with a lot of surface area? or am i wrong on this too? ???
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When people talk about glues being 'gap filing' they are actually talking about microscopic gaps. No glue is a filer for poor mating surfaces. I never ever roughen surfaces up more than 80 grit paper. In some situations it can be useful to use something like a toothing plane but really that is more to do with making a starve proof joint.
If you want definate answers to your glue problems I always say to people contact the manufactures and ask to speak to a tech guy or if that isn't possible get them to send you a specification sheet. Every glue has one and it will tell you everything (and more) that you need to know.
I've seen an awful lot of things written by people about different glues, well meaning but slightly off the mark. The people who KNOW are the people who make it.
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Mike, I'm not talking about microscopic gaps. I'm talking about gaps you can see with the naked eye.
Yes, a toothing plane, hacksaw blade dragged sideways, a lam grinder, a piece of coarse sandpaper, etc all leave behind a roughened gluing surface so that when certain glues are used, the joint is 'starve proof'.
Gopher, the toothing plane's cutting edge is not shaped so that the two gluing surfaces perfectly recieve one another. You can clamp as tight as you want and you won't squeeze out all of the glue.
I mix Smooth On by volume.