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  #1  
Old 08-26-2018, 04:35 AM
Larsen Larsen is offline
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Default Beginning of scarf joint break?

Hello! I'm new here and would appreciate some advice.

Recently bought an old Framus acoustic. Seems like it was a more affordable model in its time but it has a trussrod.

The relief was too high so over the 3 days I adjusted the trussrod in ca. quarter turns each day. It seem to work but on the 3rd day It got a bit too tight, and a smooth curve shaped break in the finish appeared on the back of the neck.

I believe this is the early start of a scarf joint break after doing some research, but it doesn't seem to be a gap, but only a slight "mark" in the wood. It looks ugly and I can feel the cracked finish.

My question is how I go about treating it, as it doesn't look like I can get in there with a glue syringe. I tried gently bending at the headstock and look for a gap opening but it still seems rather solid and that confuses me.

A picture: https://imgur.com/a/HBleGap
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Old 08-26-2018, 06:48 AM
murrmac123 murrmac123 is offline
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Quote:
Originally Posted by Larsen View Post
Hello! The relief was too high so over the 3 days I adjusted the trussrod in ca. quarter turns each day. It seem to work but on the 3rd day It got a bit too tight,
Welcome to the forum !

There are others better qualified I to advise about the way to go about repairing the break, but it seems to me that you have made the classic error of trying to adjust the action by tightening the truss rod excessively.

When you say "the relief was too high" did you actually mean to say "the action was too high" ?

"Action" and "relief" are two different things.
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Old 08-26-2018, 07:04 AM
Larsen Larsen is offline
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A little bit of both, the neck had a big upbow when I got it so I thought that adjusting the truss rod would help with that and at the same time bring the action down a bit. I did probably confuse the two terms, and misjudged also how much I could turn the truss rod. Bad mistake!
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Old 08-26-2018, 01:30 PM
Earl49 Earl49 is offline
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A scarf joint is usually higher on the neck, where the peg head is grafted onto the main neck, right around the nut or the first fret. Your crack looks lower, more like fret #2 or so. But I don't know much about Framus guitars - maybe that location is normal?
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Old 08-26-2018, 01:57 PM
Alan Carruth Alan Carruth is offline
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That's one of those backward scarf joints, where the head piece is on the side toward the fretboard, rather than on the back of the neck. I don't know who thought that one up, but I started to see those back about twenty-five years ago on Asian imports. It's simply the wrong way to do it, and leads to problems, such as humps in the fretboard, even when it stays together. I don't imagine it's easy to fix, since the joint is weaker than the usual scarf, and almost certainly not put together with a glue that can be repaired.

For future reference: it takes a while for the neck to develop significant bow under string tension even when there is no pressure on the rod. Similarly, once you do tighten the rod it takes a while for the neck to finish moving back under the force. Simply cranking the neck back to flat from a high bow over a few days is actually putting too much pressure on it; it would keep going and eventually end up back bowed. The proper procedure is to put on some pressure, and wait for some time to see what happens. How long to wait depends on how long it's been without pressure on the rod.

Many of those low-end Asian guitars I worked on back then came in with slack strings and no pressure on the rod, as is correct. The stores would tighten up the strings but not the rod. A year later the kid would be back with a badly bowed neck and unplayable action. The correct thing to do would have been to adjust the rod slowly, taking a month or so to get it right. Of course, they needed to have the thing back right away, so you had to crank the rod right up, and then that reverse scarf would would be pushing up on the fretboard over the joint because the glue line shifted. The outcome was seldom satisfactory, but might have been if I'd been given the time to do it right.
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Old 08-27-2018, 05:42 AM
B. Howard B. Howard is offline
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Another issue that can cause this is moisture content of the wood. These issues tend to show up often on imported guitars. Even if the wood was well acclimated and the instrument manufactured in a controlled environment. Not all are.... they still are shipped over sea.

Perhaps high end or custom instruments may get the luxury of air shipment, the rest come in container boxes on cargo ships. These shipping containers do not always stay dry inside. And if they do not leak then they are airtight and will have a terrarium type effect inside them. So either way for their journey here they get pretty moist. The reason why they are shipped with rods slack perhaps.

So what happens is what I have called hydroshock over the years. The RH rises rapidly in the container causing all the wood to expand, perhaps as much as 5-7% in volume. Finish handles expansion quite well. It stretches easily in most cases. So when the container arrives and the guitars come out everything still looks like it did when it went in.

But now the wood will dry back out and shrink back to its nominal size. The faster this happens the more trouble there will be.... This is the real reason I think most shops installed RH controlled rooms for acoustic guitars only. But even if dried out slowly there will most likely be some type of finish issue. While finishes stretch easily, they do not tend to retract quite as well. Couple that with a bit of uneven movement between the two different pieces of wood and enough stress develops in the film to cause it to break and delaminate at the joint.

IME overzealous truss adjustments usually either break the cheap rod or pop the FB end off the neck.
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Old 08-27-2018, 08:50 AM
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Frank Ford Frank Ford is offline
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Offhand, I'd guess that your truss rod adjusting did not cause the separation, but revealed a weakness already there. If the rod can be adjusted satisfactorily, I wouldn't worry about it.

I would, however, try to stabilize at least that portion of the separation by leaking in as much thin cyanoacrylate (super glue) as I could. It will fill tiny gaps and hold things pretty well.
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Old 09-07-2018, 06:24 PM
BillRomansky BillRomansky is offline
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I push in Titebond rather than CA, CA is prone to crack under stress. With the strings still full tension, find the tang and just keep pushing Titebond against it really hard, just push and push with a finger. Then slacken strings and tension neck backwards just a bit with a reverse clamping setup you pre-prepared before you start the job, in the direction of a backbow. Of course, clean glue thoroughly after clamping.
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  #9  
Old 09-07-2018, 07:28 PM
mirwa mirwa is offline
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A side view of the type of scarf you have before it’s shaped and sanded

Steve

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