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PostPosted: Sun Jul 18, 2021 12:08 pm 
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Cocobolo
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Last year I repaired my friend’s Gibson EB-2 bass’s broken headstock. It never broke completely off and I had to pry it open to get glue in. I used 192 gram HHG and clamped it as best I could. It failed not long after. I think I was too timid about spreading the break open to inject glue and did not get enough glue into it. And maybe the glue was not strong enough.

I’ve re-glued it, this time with 315 gram glue and a much better clamping scheme. The break was able to close up perfectly and there were no missing bits of wood or loose fibers. I pre-warmed the area with a heat gun, had my cauls and clamps prepared and clamped it within seconds of injecting the glue. I used a syringe to get much more glue into the break and got plenty of squeeze-out all around. 36 hours later it appears to be strong when I try to flex it by hand.

I obviously don’t want this to fail again and even though I think I know what went wrong the first time and I’m confident I did a much better job this time I’m wondering if it’s necessary to reinforce the break with carbon fiber rods or even a back plate.

Can anyone offer some advice?


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PostPosted: Sun Jul 18, 2021 1:07 pm 
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Should be good.

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These users thanked the author Chris Pile for the post: bionta (Sun Jul 18, 2021 2:17 pm)
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PostPosted: Sun Jul 18, 2021 2:17 pm 
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Cocobolo
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AH.. Many thanks. It's good to get that from a serious repair person!


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PostPosted: Sun Jul 18, 2021 4:28 pm 
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Koa
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Chris are you serious? ;)


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PostPosted: Sun Jul 18, 2021 5:09 pm 
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Chris are you serious? ;)


Yuppers. I've done enough reinforcing of peghead breaks by now to realize that if good joining of the break and sufficient glue won't work, then any extra work is wasted time and materials.

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PostPosted: Mon Jul 19, 2021 3:52 am 
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Old Growth Brazilian Rosewood
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LOL yep should be good and hey Bob, I hope you are doing great and cool to see you doing repair work too. PS: Chris is inside a serious repair person, Connor too!

We don't like adding any wood or other reinforcements to head stock breaks and prefer a very good glue joint and clamping in the Collins neck jig.

When working with HHG especially the higher gram strengths which we don't use not that there is anything wrong with them mind you is an exercise in temps, prep and getting the glue deep in the wound. Consider using compressed air to help the glue be pushed into the deepest parts of the break.

I've been playing around with a different method for getting glue in top and other cracks where uber strength is not the goal but a glue joint that won't give in time is the goal. Using good ole Titebond original I cut it 50% with water and rub that into the crack (with clean fingers, glue carries dirt into crack and then forever enshrines your dirt there for all to see). I pump the crack from the underside so that the pumping action and the thin viscosity, cut Titebond migrate everywhere including producing little glue droplets on the inside of the crack/box.

Then I break out the full strength 18 year old single malt Titebond :) and rub that into the crack. The idea here and the reality is that the thinned Titebond acts as a carrier attracting at the molecular level the thick Titebond into the deepest or tightest part of the crack. I'm finding that I see much more squeeze out on the inside that I wipe clean of course which suggests better glue penetration and spread because of the thinned stuff being used as a carrier.

I'm going to try this on a head stock even though we use HHG for head stocks and see how it does. I'll probably try it about a month before I retire. :)

Hey Bob I signed up for Medicare yesterday so now I have an excuse for being me :)


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PostPosted: Mon Jul 19, 2021 9:25 am 
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Brazilian Rosewood
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I wouldn't judge the stability of the repair without at least seeing photos.


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PostPosted: Mon Jul 19, 2021 9:35 am 
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Cocobolo
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Hi Hesh. That sounds like a great idea. I imagine the thinned glue will reduce surface tension and draw in the thicker stuff. I''ll try to remember that for future repairs (although remembering anything is a challenge these days...) As soon as I can get my friend to pony up for a set of strings (his were decades old) I'm going to string it up. I've never been crazy about the sound of those Gibson short-scale basses but I love the looks and the mojo of that thing. As far as I can tell it was made between '66 and '69. Now if I could just get him to buy a case so it doesn't get busted again. Aye aye aye. He's ... ahem, ... let's say fiscally conservative.

Incidentally, I traced and measured the body because I want to build an ES-335ish guitar for myself. It's nice to have the example on hand.

Good going on the medicare. So far, I've found it to be as good as any insurance I've had and very hassle free and a who-o-o-o-le bunch cheaper. So far! But (fortunately!) I haven't put any great demands on it yet. I hope you don't either!



These users thanked the author bionta for the post: Hesh (Wed Jul 21, 2021 7:12 pm)
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PostPosted: Mon Jul 19, 2021 9:41 am 
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Cocobolo
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Barry Daniels wrote:
I wouldn't judge the stability of the repair without at least seeing photos.

Not great cosmetically, I know.

Image


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PostPosted: Mon Jul 19, 2021 10:31 am 
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Cocobolo
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Duh. Used the wrong interface to upload photos and couldn't resize. Tapatalk lets me edit the post and add properly resize pics but I can't seem to get rid of the original big photos. Sorry about that.


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PostPosted: Mon Jul 19, 2021 10:58 am 
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Brazilian Rosewood
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Some Gibsons have very little wood in this area when you factor in the truss rod cavity. I had one that had less than a 1/16" of wood between the cavity and the back of the neck. Being as how it was glued once and failed, I would say the chance for failure again on this neck is good.

I would likely put some type of reinforcement on there like splines or a backstrap. But I am sure that no one else here would agree with me.



These users thanked the author Barry Daniels for the post (total 2): bionta (Thu Jul 22, 2021 9:25 am) • Hesh (Wed Jul 21, 2021 7:13 pm)
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PostPosted: Mon Jul 19, 2021 11:49 am 
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Barry Daniels wrote:
Some Gibsons have very little wood in this area when you factor in the truss rod cavity. I had one that had less than a 1/16" of wood between the cavity and the back of the neck. Being as how it was glued once and failed, I would say the chance for failure again on this neck is good.

I would likely put some type of reinforcement on there like splines or a backstrap. But I am sure that no one else here would agree with me.


Yeah, I agree there is very little wood there. I think a little less than 1/4" under the truss rod nut.

So far I have professional repairers responding both for and against reinforcement. Considering my inherent reluctance to try something I've never done before on this vintage instrument, if it isn't insane to go without it I'm inclined to leave it as it is and tell my friend that if it fails again he should take it to someone with more experience. (I told him that the first and second times but he "trusts me". And I'm not charging him.) It obviously needs finish repair that I'm also not undertaking. He doesn't care about the cosmetics. Before the first repair he offered to give me the bass but I insisted that if he doesn't care to keep it he should sell it. He's had the thing since the 60s and his son enjoys playing it. But if he repeats that offer I'll fix the finish, sell it, pay myself for the repair and give him the rest of the dough.

Many thanks to all who've responded. I can't overstate the value of a pro's perspective.


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PostPosted: Mon Jul 19, 2021 11:54 am 
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I think it will be fine. And since no money exchanged hands, the client has no gripe if it breaks again next time he drops it.

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These users thanked the author Chris Pile for the post (total 2): bionta (Thu Jul 22, 2021 9:25 am) • Hesh (Wed Jul 21, 2021 7:13 pm)
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PostPosted: Wed Jul 21, 2021 7:20 pm 
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Old Growth Brazilian Rosewood
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Barry Daniels wrote:
Some Gibsons have very little wood in this area when you factor in the truss rod cavity. I had one that had less than a 1/16" of wood between the cavity and the back of the neck. Being as how it was glued once and failed, I would say the chance for failure again on this neck is good.

I would likely put some type of reinforcement on there like splines or a backstrap. But I am sure that no one else here would agree with me.


I don't disagree this may be bad enough and more reinforcement would certainly be welcome. That does get into a much more involved repair making the economics not work in either time or expense perhaps for someone.

Regarding Gibson's lack of wood on many of their designs I would estimate that of the headstocks that we repair 80% of them are Gibson. And then once they've carved out too much wood from the truss rod cavity they use a huge nut and spray black lacquer over it..... Nothing but the best :)



These users thanked the author Hesh for the post: bionta (Thu Jul 22, 2021 9:25 am)
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PostPosted: Wed Jul 21, 2021 8:18 pm 
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Cocobolo
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The thing about this idea of reinforcement that bothers me the most is the pucker-inducing thinness of the neck, along 2 axes. Not only is the neck thin from front to back (about 20 mm before subtracting the depth of the truss rod channel and the huge divot for theTR nut) but the nut is only 1-1/2” wide. That leaves a little splinter of wood on either side of the TR in which to route a channel for the reinforcement.

Yikes.



These users thanked the author bionta for the post: Hesh (Thu Jul 22, 2021 3:57 am)
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PostPosted: Thu Jul 22, 2021 8:37 am 
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Brazilian Rosewood
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I have placed carbon fiber rods for splines that partially run through the truss rod cavity in situations like this.



These users thanked the author Barry Daniels for the post: bionta (Thu Jul 22, 2021 9:26 am)
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PostPosted: Thu Jul 22, 2021 9:24 am 
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Cocobolo
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Barry Daniels wrote:
I have placed carbon fiber rods for splines that partially run through the truss rod cavity in situations like this.


HI Barry, If you were local I'd be taking this to you but I don't think this is something I should attempt. I'll show my friend the opinions on this thread and let him decide if he wants to get a pro to reinforce it. Thanks!


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PostPosted: Mon Aug 02, 2021 6:29 am 
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Cocobolo
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That repair does look pretty good on the outside. On the other hand, this is what that Gibson neck looks like on the inside.
Attachment:
9F2CECCE-125A-4420-AFB1-73FEC8351ACA.jpeg


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PostPosted: Mon Aug 02, 2021 8:59 am 
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Cocobolo
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The jury is in. Unfortunately, after less than 24 hours of string tension it’s starting to open again. I think you can see it in this photo. I’ll have to talk to my friend about the next steps because, as I said, I’m not too inclined to tackle it and I know he’s not too inclined to spend money on it.

Image


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PostPosted: Mon Aug 02, 2021 9:21 am 
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Brazilian Rosewood
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I'm not surprised.


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PostPosted: Mon Aug 02, 2021 11:25 am 
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Rather than splines which I think would be a big hassle to install, why not a back strap over the break? Here is a Guild 12 string with two truss rods so putting splines in might be a major problem. Glued and clamped the break, then thinned the head and part of the neck with a Safe-T-Planer. Bent a piece of mahogany and laminated it over the break.

Attachment:
IMG_3435.JPG


Attachment:
IMG_3459.JPG


Attachment:
IMG_3475.JPG


This repair was done in 2016 and its a 12 string so around 230 pounds of tension. I just got a note from the owner that he is opening at the local county fair so the repair is holding up fine.


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PostPosted: Mon Aug 02, 2021 1:09 pm 
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Brazilian Rosewood
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Good job on that one, Freeman. I have a current repair on an Epiphone where I threw the whole book at it. Splines, backstrap, and reinforcement on top. It was a bad break all the way through. You might ask, was the guitar worth that much work? No, of course not. But I am not doing this for a living.


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PostPosted: Mon Aug 02, 2021 3:24 pm 
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That looks really great Freeman. If I allow myself to get roped into this I’ll definitely consider that method.


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PostPosted: Mon Aug 02, 2021 5:51 pm 
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bionta wrote:
That looks really great Freeman. If I allow myself to get roped into this I’ll definitely consider that method.


When you think about the torque on the head of a guitar around the nut I think reinforcement on the very back of the neck makes all sorts of sense. It really wasn't that hard to do, I bend a piece of mahogany on my pipe, planed down the back of the head the same amount and just feathered it way at the neck. The fact that it is holding up makes me feel pretty good aboout the method.


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PostPosted: Mon Aug 02, 2021 6:33 pm 
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Brazilian Rosewood
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One solution may not be appropriate in all cases and it may need to be modified depending on the type and extent of the break. A backstrap is good if the crack does not go all the way through into the nut slot or headstock veneer. It the headstock veneer is compromised, a backstrap may not be enough. A break through a Gibson truss rod nut recess may be best repaired with splines. Some breaks go directly across the grain which may need multiple techniques, like the Epi I mentioned in a previous thread.

The last time I used splines I used short and small carbon fiber bars instead of the normal wood splines.


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