Primitive Archer
Main Discussion Area => Bows => Topic started by: Selfbowman on November 30, 2020, 02:32:25 pm
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Making a heavy one . Unibond 800 or Hyde glue.
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Unibond.
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Unibond 800 in case available (not here in Finland).
Smooth-On EA-40 works also fine and easier to get here.
I’ve heard TiteBond III has been used succesfully also but that requires absolutely fully compatible sanded surfaces, no gaps and proper clamping. Sanding is necessary because of bamboo is poor absorber of water based glues.
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I have made a pile of BBOs glued up with Urac 185 ,never had a glue joint fail. I switched to Unibond when they quit making Urac, so far so good.
I tried EA-40 it worked OK but I always get more on me than the bow and cleanup takes some serious solvents to get it off.
You can't heat and correct a smooth on glued bow either, something I often do after a glue-up.
I could heat correct anything glued up with urac, I had a tip overlay pop off when I heat aligned the tips of a static glued up with Unibond.
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Nothing water based. Bamboo is a sponge and takes weeks to dry once you use tight bond. Id use epoxy of some kind.
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"You can't heat and correct a smooth on glued bow either, something I often do after a glue-up."
Incorrect sir. I've done it many, many times. Bamboo backed bows, trilams, and glass/wood laminated bows. Sometimes multiple times in the same section of limb if needed. Never had one fail. Smooth On can take it.
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Perhaps I am wrong but I thought when you got smooth-on up to the temperature it cured at it would turn loose. It is good to know it won't turn loose. I do know I have delaminated a few fiberglass laminated bow trying to heat the limbs and take the twist out but no telling what they were glued up with.
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Eric I was under that same impression... I only used unibond since it is urac 185 basically..
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Perhaps jeff uses a hotbox at a high temp to cure and then future heat correction only brings the glue to a slightly lower temp.
Epoxy can be manipulated at its glass transition temp where it becomes "plastic" but does not actually start to break down.
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Pat, I use a hot box, which is 185 degrees, for my glass bows. When it comes to bamboo backed bows, trilams and such, some are cured at room temperature, and some may go in the hot box if the jig and clamps will fit. I never noticed a difference between them when making heat corrections.
I've never checked the temperature of the wood after heating with the heat gun to make a correction. I gauge it by feel, but I'm guessing it's at least 185 degrees. I now have a lazer temp gun. I'll check it next time to see how hot it gets.
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I've used TBIII, Urac and Weldwood Plastic Resin, all with good success and no glue failures. With the Urac and Weldwood I used a heat box at 168 deg and lower heat for the TBIII. TB glues break down at 150deg(F).
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I use West Systems 105/205. I have done a few string alignments with dry heat. They were on recurves so it was more a twist than a bend. I think the secret is that you heat the belly. Wood is a great insulator and you can get the belly "hot" enough to take the bend without getting the back hot enough to release the epoxy. Also it really doesn't take a lot of heat to twist a bow.