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PostPosted: Mon Nov 06, 2017 2:27 pm 
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Mahogany
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So I've got my hands on this classical guitar, the heel is cracked. I feel like i could pry the crack open enough to get some titebond in there and then clamp it. Is this a sufficient fix for this kind of thing?


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PostPosted: Mon Nov 06, 2017 2:38 pm 
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Here's another picture of the top...


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PostPosted: Mon Nov 06, 2017 2:46 pm 
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I see two cracks. And something is going on between the heel cap and the back binding. I think the guitar got cooked in a hot car. What kind of neck joint does this have?


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PostPosted: Mon Nov 06, 2017 3:07 pm 
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I'm assuming it's a spanish heel, that's traditional for classicals right? Is there a way to tell? The neck block inside the guitar seems a little thinner and wider than on a steel string guitar. The guitar was made in Japan for a store in Vancouver BC, it looks like a pretty good guitar. The rosewood back and sides are pretty stunning, and the top has nice tight grain for a cedar top.

Upon further inspection the neck angle looks really goofy, goofier than even the cracked heel would suggest. The bracing seems okay inside but it looks like the top is collapsing in on itself.


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PostPosted: Mon Nov 06, 2017 4:03 pm 
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Brazilian Rosewood
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I don't quite get that second picture in your last post. Did you remove the heal entirely or am I missing something? Anyway if you can clamp that heal back together then yes injecting with Titebond and clamping over night will fix it right up. You can even dilute Titebond up to 10$ to get good penetration which might be necessary for that tighter crack. It's normal for classical guitars to have forward neck angle. That might be a bit excessive but then that crack is pretty open too. You could clamp it closed and see if the angle changes.


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PostPosted: Mon Nov 06, 2017 4:09 pm 
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I can't tell from the picture but those cracks look like they might be glue failures in a stacked heel. That would jive with Barry's hot car Dx. If that is the case, you can't just put titebond in and reclamp.

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PostPosted: Mon Nov 06, 2017 4:19 pm 
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jfmckenna wrote:
I don't quite get that second picture in your last post. Did you remove the heal entirely or am I missing something? Anyway if you can clamp that heal back together then yes injecting with Titebond and clamping over night will fix it right up. You can even dilute Titebond up to 10$ to get good penetration which might be necessary for that tighter crack. It's normal for classical guitars to have forward neck angle. That might be a bit excessive but then that crack is pretty open too. You could clamp it closed and see if the angle changes.


Sorry, it's just the angel the picture was taken at. The heel is still there.


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PostPosted: Mon Nov 06, 2017 4:20 pm 
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Mahogany
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Bryan Bear wrote:
I can't tell from the picture but those cracks look like they might be glue failures in a stacked heel. That would jive with Barry's hot car Dx. If that is the case, you can't just put titebond in and reclamp.


By stacked heel, so you mean the heel is carved from several pieces of wood rather than one solid piece of wood? If so yes that's the case. If I can manage to clean the old glue out, can I then glue with Titebond and clamp?


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PostPosted: Mon Nov 06, 2017 4:38 pm 
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Yes I mean that the neck shaft has several pieces of wood (about the same thickness of the neck shaft) built up and glued together to form the heel. If that is the case, and it is indeed separated at the glue line, I'm not the person to ask how to fix it.

If you knew that it was glued with hide glue, you could use that but titebond or similar won't stick to itself. I'm not sure how you would get the old glue cleaned out without doing too much damage to the joint but some of the experience repair folk might have a plan. If you knew what kind of neck joint it had and it wasn't a Spanish heel, taking the neck off might help but it looks like it was finished with the neck on so that creates its own issues.

Perhaps epoxy would would stick to dried wood glue. Hopefully someone who knows will chime in.

I would be concerned that there are other issues beyond the cracked heel. If the heel delaminated I would expect loose braces and or bridge. Is the top deformed? Can you see any loose braces?

Keep in mind that all this is moot if we are talking about cracked wood and not glueline failures.

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PostPosted: Mon Nov 06, 2017 4:56 pm 
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Brazilian Rosewood
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I know you are not 'supposed' to be able to reglue a joint like that with Titebond but you actually can and I tested it myself to prove it. If you are worried about it though CA or Epoxy would work, it's just potentially messier. I have also tested CA on dried delaminated Titebond joints and it is strong.



These users thanked the author jfmckenna for the post (total 2): pat macaluso (Tue Nov 07, 2017 2:22 am) • Bryan Bear (Mon Nov 06, 2017 5:32 pm)
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PostPosted: Mon Nov 06, 2017 5:33 pm 
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jfmckenna wrote:
I know you are not 'supposed' to be able to reglue a joint like that with Titebond but you actually can and I tested it myself to prove it. If you are worried about it though CA or Epoxy would work, it's just potentially messier. I have also tested CA on dried delaminated Titebond joints and it is strong.


Interesting! I have never actually tried it.

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PostPosted: Mon Nov 06, 2017 7:38 pm 
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Conor_Searl wrote:
I'm assuming it's a spanish heel, that's traditional for classicals right? Is there a way to tell? The neck block inside the guitar seems a little thinner and wider than on a steel string guitar. The guitar was made in Japan for a store in Vancouver BC, it looks like a pretty good guitar. The rosewood back and sides are pretty stunning, and the top has nice tight grain for a cedar top.

Upon further inspection the neck angle looks really goofy, goofier than even the cracked heel would suggest. The bracing seems okay inside but it looks like the top is collapsing in on itself.


You really can't tell from looking inside - sometimes a Spanish heel just looks like a big neck block, sometimes it has kind of a "foot" that extends down the back of the guitar. If you see a bolt head or two you know its a bolt on but it is hard to tell if its a dovetail or not. Ironically many of the classicals coming in from Japan do have dovetail joints, usually they also have a truss rod. Here is a picture of a Spanish heel fwiw

Image

You also comment in your first post that part of the heel is pulling away from the body - that really can't happen with a Spanish heel since the heel is part of the body - the sides are slotted into it. You can sort of see that in the picture

The neck angle in your second picture is totally wonky - that straight edge should just sit on top of the bridge. I'm going to agree with the left-in-a-hot-car theory.


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PostPosted: Mon Nov 06, 2017 8:02 pm 
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What happens is that the hot car will soften up the glue joints and any joint that has stress on it (like the neck joint) will slip. And slippage at the neck joint places tremendous stress on the heel that leads to cracks.

I have "repaired" a couple of steel strings with this condition by heating up the internals around the head block will using a clamping setup to pull the neck back into position. But the cracked heel in this case makes that kind of operation quite a bit more risky.

I would consider this a situation where a neck reset is appropriate, assuming it is not a spanish heel. If it is a spanish heel then it might be a terminal case, because the head block will be cracked too. If you just want to experiment then you could cut the neck off, re-glue the heel and block, and then convert it to a bolt-on.


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PostPosted: Mon Nov 06, 2017 8:18 pm 
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Bryan Bear wrote:
I can't tell from the picture but those cracks look like they might be glue failures in a stacked heel. That would jive with Barry's hot car Dx. If that is the case, you can't just put titebond in and reclamp.



+1 except I'm guessing maybe water damage.

First fork in the road is: real fix, hail Mary, or target practice.

To choose you would need to know:
1. What's the value of the instrument.
2. what is the neck joint type.

A posted photo of the label and illuminated neck block might tell the tale. I'd put a light and mirror in there and look for water marks too.


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PostPosted: Mon Nov 06, 2017 10:15 pm 
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Mahogany
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Freeman wrote:
You really can't tell from looking inside - sometimes a Spanish heel just looks like a big neck block, sometimes it has kind of a "foot" that extends down the back of the guitar. If you see a bolt head or two you know its a bolt on but it is hard to tell if its a dovetail or not. Ironically many of the classicals coming in from Japan do have dovetail joints, usually they also have a truss rod. .


For what they're worth here are a couple pictures of the neck block. No truss rod.


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PostPosted: Mon Nov 06, 2017 10:37 pm 
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That’s not a Spanish heel or you would be looking at endgrain, no bolts showing either so I guess that leaves dovetail. Looks like a good opportunity to learn to reset a neck. I would think you can fix the heel more easily with the neck off. Don’t forget to cut through the finish in the corners before you try to separate the neck from the body.

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PostPosted: Thu Nov 09, 2017 12:15 am 
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Mahogany
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Or possibly a dowelled joint.


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