Some pics first ...
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| Repair of headstock glueline failure http://www-.luthiersforum.com/forum/viewtopic.php?f=10137&t=52163 |
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| Author: | Tim Mullin [ Wed Jul 10, 2019 7:08 pm ] |
| Post subject: | Repair of headstock glueline failure |
Have a Norman Dreadnought on the bench, ca. 1996. The guitar suffered a party accident, leading to much spilled beer and a broken headstock. The beer cleaned up nicely, but now I’m faced with the headstock — the scarf joint glue-line failed, and the headstock is hinged quite securely by the headplate. Everything lines up very well, but the glueing surface is obviously contaminated with old glue. Would be OK if it was HHG, but I suspect it’s a PVA. I’m thinking CA or epoxy. If epoxy, I think I’ll need to scratch up the surfaces to give something for the glue to key to. CA would be easy, until it comes time to cleanup. Any experience with this sort of break? Sent from my iPad using Tapatalk |
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| Author: | phavriluk [ Wed Jul 10, 2019 7:57 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
This broke at the site of a prior repair (or multiple prior and ultimately unsuccessful repairs)? |
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| Author: | Tim Mullin [ Wed Jul 10, 2019 8:03 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
No prior repair. This broke along the glue line of the factory scarf joint. Never had one like this — if it were clean broken wood, there would be no problem Sent from my iPad using Tapatalk |
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| Author: | phavriluk [ Wed Jul 10, 2019 9:15 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Time for somebody who knows what he/she is doing to speak up. Listening to us sidewalk superintendents can be hazardous. |
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| Author: | Chris Pile [ Wed Jul 10, 2019 11:36 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Pix would be a help..... if you can. |
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| Author: | B. Howard [ Thu Jul 11, 2019 6:15 am ] |
| Post subject: | Re: Repair of headstock glueline failure |
Assuming you can access the joint faces to tooth up for epoxy then you could also use PVA like titebond. I reserve epoxies for the last resort.... when the job has been bungled by several others first. But before we talk repair strategies, lets talk about the break itself.You say the joint failed, did the glue fail or did wood shear right beside the joint? If it failed do to improper initial fit up then epoxy may be your only solution and even it may not hold well down the road either because no glue will ever compensate for poor fit up. Glue joints that fail are serious warning signs about quality of construction. I personally always run my scarf joints up under the FB for better structural support. Rather than use the head face veneer to reinforce the joint you have the end of the FB to do the job. This is an area where I think Hesh's philosophy of "serviceability" comes to mind but most builders do not like the ascetics of the joint running through the neck shaft at an angle..... |
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| Author: | Tim Mullin [ Thu Jul 11, 2019 9:35 am ] |
| Post subject: | Re: Repair of headstock glueline failure |
Some pics first ... Sent from my iPad using Tapatalk |
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| Author: | Tim Mullin [ Thu Jul 11, 2019 9:48 am ] |
| Post subject: | Repair of headstock glueline failure |
Yes, this is a glue failure — the surfaces along the joint are perfectly flat and uniform finish. It is very difficult so see any signs of glue, so the original joint was tight. Oddly enough, just last week I had another older Norman in here with a fingerboard separated from the neck. Obviously, the owner got carried away with the truss rod and popped it right off. Again, the wood was completely undamaged — the failure was along the glue line itself. Cleaned up both surfaces and reglued with TB. At this point, I’m thinking along Brian’s suggestion of cleaning the joint as much as possible using sandpaper on the thinnest steel rule I have (about 0.060”). I won’t be able to reach the deepest portion of the glue line. Then use HHG to reglue. If it ever breaks again, I think that will be a better starting point than any other glue. After cleanup, I would wick CA from the side I to the broken wood portion, where the HHG won’t reach. The key will be to maintain a tight joint while exposing as much uncontaminated wood as possible. Any other ideas? BTW Brian, I’ve never liked putting the scarf under the fingerboard. The first neck I ever repaired was built that way. I put a thickish backstrap on all my guitars, with the exception of classicals. They are pretty much the strongest headstock possible and much more likely that the neck itself is the weak point. No matter what we do, we’re not likely to make a guitar that’s Pete Townsend proof! Sent from my iPad using Tapatalk |
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| Author: | Goodin [ Thu Jul 11, 2019 12:49 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Sounds like a good plan to me. Clean it, glue it, clamp it. I would also use HHG for this glue up. After the glue cures I would string it up, and give it a few firm taps on the back of the headstock to make sure the joint is strong and maybe keep it for a while under string tension before giving it back to the customer to make sure it holds up. If the glue joint fails I would put on a back strap. Is that indeed a glue joint failure or did the wood sheer? If it's wood sheer I probably wouldn't sand it. Not really necessary unless it's really dirty and sanding down any of the wood may make the glue surfaces not mate up properly. Right now you have a perfect fit. But yeah if the break is along the glue line you would need to remove the old glue out of the joint. I like sticking sandpaper on feeler gauges to get in tight spots like this (like under loose braces and such). |
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| Author: | rbuddy [ Thu Jul 11, 2019 1:24 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
This might be a good way to remove the old glue residue. I have some but have not had to use it. Sanding might make the joint fit worse. http://www.de-gluegoo.com/ StewMac carries it. |
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| Author: | Chris Pile [ Thu Jul 11, 2019 3:04 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Do NOT use CA on this repair. I see very little glue in your pix, suggest you wick some Titebond or hide glue into the joint by flexing it a bit. Also, let gravity do its thing by putting the peghead on the floor before clamping it up. I think it will fine. |
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| Author: | B. Howard [ Thu Jul 11, 2019 3:24 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Tim Mullin wrote: BTW Brian, I’ve never liked putting the scarf under the fingerboard. The first neck I ever repaired was built that way. In all the nightmares I have seen which include laminated necks snapped clean off I have only ever had one neck with the scarf under the board come in broken at the joint. Tim Mullin wrote: No matter what we do, we’re not likely to make a guitar that’s Pete Townsend proof! I got an old Kramer with a Forged aluminum neck and rock maple body that is as close as you get to that! 
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| Author: | Tim Mullin [ Tue Jul 16, 2019 3:23 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
B. Howard wrote: Tim Mullin wrote: BTW Brian, I’ve never liked putting the scarf under the fingerboard. The first neck I ever repaired was built that way. In all the nightmares I have seen which include laminated necks snapped clean off I have only ever had one neck with the scarf under the board come in broken at the joint. Hey, me too! And it was one of my first!  Sent from my iPad using Tapatalk |
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| Author: | Tim Mullin [ Tue Jul 16, 2019 3:26 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
I carefully cleaned it up as best I could to P120 and used 260g HHG. Practically invisible. Now we’ll see if it holds. Sent from my iPad using Tapatalk |
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| Author: | SteveSmith [ Tue Jul 16, 2019 4:08 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
Got an after photo Tim? |
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| Author: | Tim Mullin [ Tue Jul 16, 2019 4:59 pm ] |
| Post subject: | Re: Repair of headstock glueline failure |
SteveSmith wrote: Got an after photo Tim? You’d think I would, but I forgot before the client picked it up yesterday. One thing I like about HHG is it cleans up so easily and virtually refinishes any small edge defects. No other touch up required. Sent from my iPad using Tapatalk |
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