Primitive Archer

Main Discussion Area => Bows => Topic started by: rocko on April 28, 2007, 03:27:06 pm

Title: de-lam delimma
Post by: rocko on April 28, 2007, 03:27:06 pm

I recently completed a bamboo backed osage straight limb bow, that I sent to a person in Canada. The backing de-laminated shortly after stringing.
I used 2-ton epoxy. I prepped the gluing surfaces by scoring, cleaning with alcohol, and applying glue to both surfaces.
I tillered the bow using a yoke and pulley system so that the limbs could be exercised and in doing so I probably pulled the bow to it’s finished draw weight several hundred times. After the bow was finished I probably shot it 100 times with no indications of any problems.
I  have made a lot of these bows using the same methods...several that I have are 5 or 6 years old and are shot frequently and never had any problems once the bow has been this thoroughly shot in.

What happened??
climate/humidity change?(I live in Kansas and the humidity was around 50% while I was making it.)
Possibly extreme temperature change during shipping??

Any of your thoughts are greatly appreciated.

Title: Re: de-lam delimma
Post by: Badger on April 28, 2007, 03:34:35 pm

Rocko, 2 ton epoxy is not suitable for this type of use. Either tightbond3 or urac will serve you much better. I had tried many epoxies in the past and had many failures with them, sometimes they worked but I never trusted them once I switched glues. Steve

Title: Re: de-lam delimma
Post by: Pat B on April 28, 2007, 03:43:33 pm

I agree with Steve. 2Ton epoxy isn't suited for the stresses a bow goes through.  There could have been extreme temps, both hot and cold while shipping. I know extreme heat will effect 2 ton epoxy. I don't know about cold.   Pat

Title: Re: de-lam delimma
Post by: D. Tiller on April 28, 2007, 04:06:23 pm

Yep! I use TBIII and have never had a problem. I dont think the 2 ton works well with wood. If you want to use a resin like glue go with Urac but I have to say TBIII has never gone wrong on me and tends to be less expensive.

David T.

Title: Re: de-lam delimma
Post by: rocko on April 28, 2007, 05:24:04 pm

Thanks for the input. I'll try the TB3 next bow. I'm still stumped on what caused the glue to fail. It wasn't under stress, it just didn't survive the trip. The guy never launched an arrow. yet it was a nice shooter before it left.

Title: Re: de-lam delimma
Post by: D. Tiller on April 28, 2007, 05:30:15 pm

I think temp and humidity change did it. The 2 ton epoxy will not swell and shrink with humidity like the wood does. So it splits away from the wood.

Title: Re: de-lam delimma
Post by: rocko on April 28, 2007, 05:34:12 pm

Sounds like a good explanation. Thanks.

Rock

Title: Re: de-lam delimma
Post by: Justin Snyder on April 28, 2007, 05:37:08 pm

Don't forget it is a boo/wood bow. You cant always explain why it does what it does. However if Steve and Pat say 2 ton isn't good for bows, you can bank on it. Justin