What glue for broken peghead

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What glue for broken peghead

Postby Bryan Bear » Mon Feb 12, 2018 1:43 pm

I am working on a guitar that has a laminated neck and a scarf joint. The laminations are maple/jatoba/maple/jatoba/maple where the 3 center laminations are just over 1/2” wide. The blank was laminated then the scarf was cut and glued. I glued the front veneer onto the peghead then made a stupid mistake when gluing the back veneer on. I like to do the curved volute on the back of the peghead requiring the back veneer to be bent to match. In order to ensure the veneer (about 1.5 mm thick bubinga) gets clamped well, I use a caul that is shaped closely to the curve on the back of the peghead but also sandwich some firm foam between the caul and the peghead then clamp it all really hard. The heavy clamping pressure compresses the foam and evens out any gaps the caul may have had.
Well. . . this time I screwed up. Without thinking, I used two cauls for the front of the peg head instead of one. That meant that the force compressing the foam wanted to bend the peghead at the space between the face cauls. Snap!
I now have a broken peghead with the back veneer in place and the face veneer broken at the inlay lines. I can tell from looking at the sides that one side was wood failure but the other looks like the scarf joint failed (I’m not sure how much is wood failure and how much is glue). I don’t know if the 3 center lams broke or the joint failed. I can easily push the parts together and close the cracks because the back veneer is holding strong. If it were all wood failure, I would work some HHG in there, clamp and never give it a second thought. But since I know there will be some part of the joint that is old titebond I don’t know what to do:
1) Proceed with HHG because it will stick well enough to TB?
2) Use epoxy because it will stick to TB?
3) Remove the veneers somehow, get to bare wood, reglue and make new veneers and inlay
4) Make a new neck
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Re: What glue for broken peghead

Postby Barry Daniels » Mon Feb 12, 2018 2:25 pm

Pictures?
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Re: What glue for broken peghead

Postby Bryan Bear » Mon Feb 12, 2018 2:34 pm

Ha! I knew someone would ask that. In my frustration last night I just walked out of the shop and went to bed. I unclamped it this morning and did a quick inspection before I clamped it closed and flat. I didn't thing to take any pictures. Maybe I should have used 1,000 words in my description <G> I'll try to take some tonight.

Edit to add:

I suppose there is no harm in gluing it back together and then loading it up to see if it holds. If it doesn't, I was going to have to make a new neck anyway. I guess the question is what glue is most likely to bond well enough. I only get one shot.
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Re: What glue for broken peghead

Postby Barry Daniels » Mon Feb 12, 2018 3:39 pm

Titebond will not stick to itself (no matter what they say on the OLF). I would slide some sandpaper into the joint to roughen the surfaces and then glue it with 24-hour epoxy. It will stick to most everything.
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Re: What glue for broken peghead

Postby Bryan Bear » Mon Feb 12, 2018 3:45 pm

Barry Daniels wrote:Titebond will not stick to itself (no matter what they say on the OLF). I would slide some sandpaper into the joint to roughen the surfaces and then glue it with 24-hour epoxy. It will stick to most everything.


Barry, in this scenario, am I using sandpaper to tooth just the joint failure surface or also the wood failure surface? I have never use epoxy for anything structural (just inlays and stuff). Does it need to be roughed up even if you have perfect wood to wood contact because the split along the grain? I suppose by the time I get there it won't be perfect since it has been opened and the surface energy will be lower even though it is currently clamped shut.
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Re: What glue for broken peghead

Postby Barry Daniels » Mon Feb 12, 2018 3:51 pm

No, the sandpaper is only needed on previously glued areas. Bare wood will be fine without any sanding. And don't worry about the surface energy stuff if the crack is only a few days old. The main thing is just to get the glue into all areas of the break and then get good clamping to close up the cracks. Glue cleanup should be pristine because any residue will be harder than the surrounding wood so it is difficult to level. I prefer West Systems epoxy but there are other good brands that will work well too. Just be careful of the hardware store stuff. It is not the same quality.
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Re: What glue for broken peghead

Postby Bryan Bear » Mon Feb 12, 2018 4:32 pm

Thanks for all your help! This is probably a dumb question but. . . If I'm pulling out the dried glue with sandpaper, is there any reason I can't use HHG? That would be my preference for a couple reasons but there may be something I'm not considering.
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Re: What glue for broken peghead

Postby Arnt Rian » Mon Feb 12, 2018 5:20 pm

HHG is great if you can get a nice tight joint with wood to wood contact all the way, that seems unlikely in this case. Since you also broke the front veneer, you'll probably want to replace that too. I'd start over with a new neck.
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Re: What glue for broken peghead

Postby Bryan Bear » Tue Feb 13, 2018 3:55 pm

If I go with epoxy, I will obviously not be just using whatever is hanging in the big box store. Let's pretend I know nothing about epoxy, is there a good product that I can buy in a very small quantity and preferably purchased locally? Would this be something a hobby shop might carry? I doubt I will be using it much after this fix so I don't want to buy big cans of resin, hardner and pumps when I only need 1/2 oz. of glue.
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Re: What glue for broken peghead

Postby Barry Daniels » Tue Feb 13, 2018 4:31 pm

Whatever you get, just make sure it is the 24 hour cure type and not the 5 minute stuff. I can't recommend any other brands than West Systems. I buy it locally at West Marine outlets, but now there is a new Rockler nearby which carries it. And they do sell it in smaller quantity packages. By the way, I gave up on the pumps several years ago because within a year they were dispensing inaccurately. Now I use an electronic scale and I can accurately mix up tiny batches if the job calls for it.
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Re: What glue for broken peghead

Postby Clay Schaeffer » Thu Feb 15, 2018 6:26 pm

West Systems packages smaller quantities of their epoxy in "repair kits". You might be able to find them at Marine supply stores or online. I use loctite "heavy duty" epoxy sold at the big box stores for some glue ups. It is a five minute epoxy that claims high strength, but I doubt it is as good as West system stuff. It sounds like you do have a large gluing surface when you add things together so maybe less than maximum strength would be O.K.
One thing to consider is the quality of the work the neck is being attached to. If it is a high quality body that is perfectly executed then adding a less than perfect neck might not be the way to go (save it for a body you really bollocks up :lol: )
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Re: What glue for broken peghead

Postby Bryan Bear » Mon Feb 19, 2018 10:40 am

I finally made it to woodcraft to get some epoxy. I suppose it would have been faster to just order some after all. I removed the face veneer cleaned the break as best as I could. Everything seems to have gone well. I left the back veneer in place because it clamping really easy. I won't have much time for it this week so it will get several days to cure. I''ll sand off the back veneer and inspect the joint and see if it holds up to some stress. If I think it is good to go, I'll apply new face and back veneers. I'll go thicker with these than I originally did to allow for more long grain support on the skins across this joint.

If I don't like the joint; I'll remove it, plane a new scarf angle on the peghead and graft new wood on. Since the neck is already partially carved, clamping this up will be a challenge. I'll do this mostly for the experience since I have nothing to lose at that point. I have seen plenty of people do really great repairs on finished instruments with severed heads so I may as well try.
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Re: What glue for broken peghead

Postby Bryan Bear » Wed Feb 21, 2018 2:04 pm

Thanks for all the input guys!

I unclamped and cleaned up the peghead. The repair looks great and feels plenty strong. Now I have a supply of "non-hardware store" epoxy so who knows, maybe I'll start using it for more things instead of only for non-structural applications.

Thanks again.
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Re: What glue for broken peghead

Postby Ryan Mazzocco » Wed Feb 21, 2018 7:53 pm

great news! can we see it?
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