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#1
08-15-2014, 04:58 PM
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Repaired Gibson LG1 bridge came un-glued?
I was getting suspicious that the hide glue didn't cure correctly or was too weak on my bridge that I had to reglue. 192 gram strength.
It's been a month and this week it started opening back up. There wasn't much pullout originally, so I cleaned all the old glue off both surfaces. The one thing that I didn't do was heat both surfaces.......that might have been my problem. Why would it hold great for a month, then almost like over night, pull away? What should I do? Higher strength glue, try the old again, Fish glue, or Titebond? 
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#2
08-15-2014, 07:15 PM
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If you did not heat the parts, I can assure you that the problem was a result of not getting the bridge clamped before the glue started to gel. There is no hope of getting a strong hot hide glue joint without clamping before it starts to gel.
Now, it's always possible there was some contamination, poor fit, or other trouble, but the chance of that being the problem is slim to none. Yes, it is absolutely "normal" for the failure to be evident later. Contrary to the name, hide glue with a greater gel strength does not produce a stronger joint. 192 gram glue is standard for woodworking; 500 requires so much extra water to become liquid, that too little actual glue remains in the joint after clamping tightly. Fresh liquid hide glue can be a great alternative for those not prepared to practice the use of and work with hot glue. Liquid hide glue takes quite an undeserved beating online in forum chatter. . .
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#3
08-15-2014, 08:49 PM
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Listen to Frank. The only HHG bridge failures I have had were because of gelled glue. Some of them lasted a year before coming loose. The gelled glue in the joint will look grainy when you get it apart again.
I only use 192 gram strength, and I mix it pretty thin. If the spruce is clean (no previous HHG residue), I apply a thinned coat of glue and let it dry. Then I heat up the parts, and apply glue to both surfaces and clamp. One habit I have adopted is to rub the glue squeeze-out with my finger as soon as I clamp, just to see if it is still liquid. If not, I unclamp immediately, separate the parts, and go again. It's not that big of a pain.
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#5
08-15-2014, 11:34 PM
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Doesn't matter how the glue gets in there.
When gluing bridges, I slop the glue on the top only, plop the hot bridge in place, clamp it up right quick. Using hot hide glue isn't rocket surgery, but it does REQUIRE practice to get to the point where occasional failure isn't part of the equation.
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#6
08-16-2014, 08:41 AM
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That makes sense. I was wondering how to heat the top section where the bridge goes.
I'm going to jump back in this morning. Remove the bridge, again, and clean up glue surfaces. Make some fresh HHG and heat up the bridge and apply the glue to the top. As before, I use a caul for the bridge plate and 3 clamps for the bridge. Should be fun, again, lol! Thanks guys!
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#7
08-16-2014, 09:54 AM
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Reading about doing this stuff is a good way to get started, but the real learning comes from doing.
That said, we could have a nice discussion about heating parts before using hot hide glue. Fortunately, it's easy to heat a bridge - ten seconds in the microwave does the job for me. I get it to about 150F before I race over to the bench to glue it. Time's a-wastin' so I get thing clamped up LONG before it cools. . .
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#8
08-16-2014, 11:22 AM
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So I tried again.
I reshaped the bridge, to make sure it matched the top radius and cleaned up the top and bridge. I heated the bridge with my iron while doing all my prep work and scored it's bottom so the glue would grip better. This time I applied the glue to the top and quickly grabbed the hot bridge and positioned it with my bridge pin locators. I wiggled it and pressed to get some seepage, then proceeded to clamp the middle. Then clamped the wings of the bridge. Torqued the clamps then proceeded to clean up. More seepage this time than last. I really hope I got it this time! When I acquired this fixer upper I didn't know if I was going to sale it or keep it. Got pretty attached in the last month with it's sound! Think I'll keep her. 
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