Primitive Archer
Main Discussion Area => Bows => Topic started by: YewArcher on July 30, 2008, 04:40:46 pm
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This questionis for you guys who do laminates. I want to do some simple laminate ELB's. A board with a wood backing strip is waht I will be using. What glue do you guys use for these? TB2 or do you use smooth on epoxy?
Thanks for any info on the glue and any other tips you may want to pass on. Orif you know of any good build alongs or helpfull threds to link to.
Thanks,
SJM
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I have used Urac for wood backings but TBII and TBIII are what I use now. Never had a failure. Also, with TB glues if you have a problem with the belly you can heat the backing strip with the heat gun and at 150deg(F) the glue will release and you can use the backing again. I'm working on a hickory backed ERC bow that developed a bad fret at a knot that runs across the limb. I will remove the backing and add it to a black walnut belly. Pat
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I have always used TBII but have some smooth on that I am anxious to try.
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I have used Urac for wood backings but TBII and TBIII are what I use now. Never had a failure. Also, with TB glues if you have a problem with the belly you can heat the backing strip with the heat gun and at 150deg(F) the glue will release and you can use the backing again. I'm working on a hickory backed ERC bow that developed a bad fret at a knot that runs across the limb. I will remove the backing and add it to a black walnut belly. Pat
Hy Pat thats some good info. I'll be able to put that to good use.
Thanks Ron
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I have used (still use sometimes) G2 Epoxy...but it's mainly for complicated glue ups with several laminations going together at once....it has an open time of an hour, and sometimes you need those extra minutes. But usually I use yellow glue (TB2) and I think the consensus is that it works just fine.
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The important thing with TB type glues is to make sure the glue surfaces are perfectly flat and to wrap it with strips of inner-tubes. I have never had a glue-line come out as pretty as I do with simple strips of rubber, I think it's because it keeps the pressure constant when the glue shrinks.
Cheers,
Grant
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As a professional woodworker I use Titebond (original) glue all the time. That stuff is incredibly strong. I have also used TB II and TB III glues as well and they are all very similar. Clamp pressure is very important. In furniture making aplications, I clamp things together for as little as 1 hour, but the glue surfaces must be perfect...that is clean (freshly machined is best) and the pieces fit with no gaps. I know that this is hard to do with bow wood pieces or laminations, but remember that if you force things together with clamps which do not fit perfectly you are risking that the pieces will "creep" back apart. Which brings me to the drawback of Titebond glues is the have the tendency to "creep" or springback. This is due to the fact that the glue is plastic in some ways and this is why the bottle says not for structural (i.e. house framing) use. I am not sure that this a draw back for bowmaking though, because of the experiences of those listed in this thread. Epoxy glues in general respond much better to ill fitting joints, and lower clamp pressures. They also have much less or no tendancy to creep. This would be an asset when making a of bent laminations like recurves or setback handles and the like.
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Steve, my first choice wouls be urac 185... But titebond 3 seems to work ok, and its readly available at most hardware stores. I don't care for epoxy's at all, to stinky and I've still had failures with it. ::)
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I learned using smooth on and I do like it. I have been using TB2 lately because of the availability and cheap price. I like the clean up on TB better than anything else, beside hide glue that is. I dont care for the fact that it delaminates at 150* because it is often over 110* here. If you leave a bow in the truck long enough to go in for a soda and pay for gas you could hit 150*. :'( Justin
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I will be removing a hickory back from an ERC bow I was working on because of a knot that runs across the limb and caused a bad fret when I got the bow to bend about 8". :'( I will take pics of the process. I have no way of knowing what temp it is while doing this. I have done it before after calling the TB folks and heat is what they suggested. 150deg(F) is what they told me.
Justin, in a situation like you have, I would probably go for another glue option. Even with some of the epoxies, heat is a consideration. Depending on the temp that the glue was cured at, if the glued up bow hits that temp or above, the glue can and sometimes does let go. I have seen braced glass lam bows come apart just sitting in a vehicle or even laying in full sun. Heat is definitely the enemy of laminated wood bows; whether just backed or a full lam glue-up. Pat
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I know what you mean Pat. I need to find an alternative but I hate ordering smooth on all the time. It can be a bit messy also. Justin
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I just removed the hickory backing strip from the ERC bow. You can see the knot in the first pic. That knot ran through the stave and exited just below the backing strip on the right side in the pic. No wonder she fretted!
I heated the tip area for about 6". When hot enough I pushed a chisel into the glue joint and began to pry. The glue started releasing and I worked my scraper under the backing and rocked it back and forth from side to side, working my way down between the backing and belly. After about 10" to 12" or so the backing strip came off fairly easily. I don't think the TBIII adhered too well to the ERC. A few specks of it did stick to the hickory backing but not much. Here are a few pics. This took all of about 10 minutes to do.
I did notice that the backing strip began to curl upward so, while it was hot, I clamped between 2 2x4s to let it cool down. If this cupping remains after it is cool, I will use the concave side as the glue side. Pat
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I've used URAC with great results.
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Justin, Urac seems to be unaffected by heat after its cured. My brother heat treats the belly on his double bamboo bows after glue up and has never had a glue failure from it. He has even recurved tips with a heat gun on a bow that was glued up with urac.
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Thanks Ryan, Ill give it a try. I checked locally yesterday and white glue is about all I can find. Ill have to order something I guess. Justin
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Pat, I have removed a few boo backings with my heat gun that were glued on with tb3, it seemed I had to get it pretty hot to do so but not hot enough to scorch,
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Steve, they say 150deg and the glue will release. I guess you have to get the wood around it pretty hot to get the glue 150deg. On the hickory backing, like you, I got it pretty hot but not quite scorch it.
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I did a car test with a couple bows glued up with tb3. It was 105 out and the car was in the sun for two hours. I took those bows to mojam...So they can take some serious heat abuse..
The other trick I learned is if one of these bows dry fires hard, usually the limb will delaminate clean, and can be re-glued. If it's glued up with an epoxy type glue, it will take material from both parts of the limb and most likely be a total loss..
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Urac here. Obviously there are lots of options. But my take is that Titebond is too finicky on needing perfect gluing surfaces and is prone to creep. Epoxy should really be cured in a large heat box, which I don't have. Urac is waterproof, doesn't creep, and fills gaps. Cheap and easy to use, too. I just can't see investing all the time to build a bow and then using anything less than the ideal glue. Resourcinal would be an equally good option, but is much more expensive. The downsides to Urac is that you have to order it (Directly from Nelson Paint is the cheapest), it has a shelf life of a year, and you can't do any glue ups below 60 or 65 degrees.
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Urac here. Obviously there are lots of options. But my take is that Titebond is too finicky on needing perfect gluing surfaces and is prone to creep. Epoxy should really be cured in a large heat box, which I don't have. Urac is waterproof, doesn't creep, and fills gaps. Cheap and easy to use, too. I just can't see investing all the time to build a bow and then using anything less than the ideal glue. Resourcinal would be an equally good option, but is much more expensive. The downsides to Urac is that you have to order it (Directly from Nelson Paint is the cheapest), it has a shelf life of a year, and you can't do any glue ups below 60 or 65 degrees.
And clean up isn't as easy as TB and you have to mix it.