Author Topic: Light through a glue joint.  (Read 3721 times)

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Offline Prarie Bowyer

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Light through a glue joint.
« on: September 27, 2011, 03:06:24 am »
I know the answer to this.  I just don't want to do it.

I took a bow of the form and unwrapped the rubber clamps and the seam at teh tip of the power lam on one side has a little gap that I can see through.  I can either heat gun the lam off, clean it off and reglue it.  OR I can try to fill it with a bit of Urac when I glue the riser on.  The seems seem fairly stable.  Glue is nicely cured this time.  The only problem is that tiny little hole.

I hope to get my bow oven completed tomorrow so I could possibly recure the bow under clamps and squeze it out.

My other deep R/D glue up had a similar problem but the Backing actualy delaminated over the powerlam.  I heat guned teh boo off and cleaned everything up, pitched the power lam and will reglue when the oven is finished. 

Think I could get away with just filling that little gap?

Offline Gordon

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Re: Light through a glue joint.
« Reply #1 on: September 27, 2011, 03:39:53 am »
I had a bow fail where there was a small gap between the powerlam and the core. I'm not saying that will happen to you, but now I'm really careful where the powerlam feathers into the core.
Gordon

Offline Prarie Bowyer

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Re: Light through a glue joint.
« Reply #2 on: September 27, 2011, 11:13:38 am »
Yea, I spent so much time on it to this point that I hated to peel the backing and start over.

Offline Del the cat

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Re: Light through a glue joint.
« Reply #3 on: September 27, 2011, 07:46:34 pm »
I'd say that you really know the answer.
If you stare deep down into you bowyer's soul you know you've go to take it off...
unless you can find some clever way to put it in a vacuum chamber or pull a vacuum on one side of the hole and then inject glue into the other >:D.
Del
Health warning, these posts may contain traces of nut.

Offline medicinewheel

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Re: Light through a glue joint.
« Reply #4 on: September 27, 2011, 08:19:06 pm »
Yea, I spent so much time on it to this point that I hated to peel the backing and start over.
Taking it off and reclueing it in this case means saving time. As Del says, you know the answer...
Frank from Germany...

Offline Bill Skinner

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Re: Light through a glue joint.
« Reply #5 on: September 27, 2011, 11:55:51 pm »
Or you can build a bow that you know will go blam sooner or later.  What's life without a little excitment every now and then?  Bill >:D

Offline Prarie Bowyer

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Re: Light through a glue joint.
« Reply #6 on: September 28, 2011, 01:54:21 am »
I'd say that you really know the answer.
If you stare deep down into you bowyer's soul you know you've go to take it off...
unless you can find some clever way to put it in a vacuum chamber or pull a vacuum on one side of the hole and then inject glue into the other >:D.
Del

I'm pretty sure I can get glue down in it.  And I'll have a shiny new bow oven finished by tomorrow. First cure was at lower temps so I think so long as I don't take it out of the from I should be good.  I'm confidant I can get glue into the hole.  I'm not so confidant that it will do any good.  Plus it will look like hell.  I already peeled one and dispensed with the power lam.  Don't need it.  Figured out one possibly better way and learned and easier way.

http://poorfolkbows.com/ipe1.htm

"Preventing catastrophe" section.

Offline Prarie Bowyer

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Re: Light through a glue joint.
« Reply #7 on: September 28, 2011, 12:55:07 pm »
HOLY SMOKES!

It's looking like this glue may not come off!  I spet a few moments with the heat gun last night and nothing was budging.  I didn't want to get things so hot that I ruined the bamboo backing.  Even the drips aren't gelling they way they did on the bow that didn't cure well.  I may need to band saw it off and then resand the back.  Light weight bow here we come!

Offline randman

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Re: Light through a glue joint.
« Reply #8 on: September 28, 2011, 03:13:42 pm »
How wide is the gap. If it is real narrow you might weep thin Cyanoacrylate glue into the crack. Shoot, let dry, repeat shooting CA glue into it until no more will suck into the crack and you build a little mound to be filed or sanded off after. Shoot it into both sides. The ca glue will weep into every nook and cranny and small fissure by capillary action and seal & fill. I've used thicker ca glue on bigger gaps and fissures also but the gap would have to be shallow because the thicker doesnt capillary as well. I learned that trick in the Guitar repair business. I've glued guitar headstock fractures (you want to talk about string tension there - 6 metal strings) and neck fractures that way without having to break the fracture apart. I had one come back broke a second time (1" away from the last repair) and the old crack held.  makes an almost invisible joint. fills tiny areas in joint lines that suck laquer finish into them (just like it does to the ca glue) and show in the finish. couple of spots of ca glue on top of the laquer finish, sand flush and re-laquer - no more sucking into the joint.
You got nothin to loose trying it (unless the gap is half the length of your bow  >:D). Sounds like a lot more work than it's worth trying to saw it apart with all the joint work getting it to mate good a second time.
Beauty is in the eye of the beer holder.

Offline Prarie Bowyer

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Re: Light through a glue joint.
« Reply #9 on: September 28, 2011, 04:27:42 pm »
Oh it's a mess.  I took the compression clamps off and found other gaps in the riser area.  The good news is that Urac holds well even if not cured at higher heats.  The bad news is that if properly mixed and cured at a reasonable heat, a heat gun won't melt the glue.  Which is good news if you don't make a mistake.  The bows will be hot car proof.

I know what my mistake was but I hate to have wasted the wood.  I love how strong it is though and the minor gap filling ability is great.

I tried the heat gun and it wasn't realy breaking down the glue with out burning the wood or bamboo.  Luckily I cut that stave a bit thicker so there is space in it for a lighter weight bow.  Or I could ad in a lamination and call it a Tri-lam.  Situation will be salvaged.

thanks for your help here guys.  I feel like I'm getting close to reproducing the bow that started this obsession in the first place.