Edumacate Me Please

richardp69

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I've owned quite a few Guilds (both 6 and 12 string) that have had cracks between the neck and the soundhole. I've always blamed pickguard shrinkage for those on the treble side (may or may not be correct) but could never dream up a reason/excuse for those on the bass side. Anybody have any insight into what might cause that??? Also, I haven't seen it on Gibson or Martin guitars I've owned but admittedly I've owned far more Guild than any other manufacturer. Any thoughts/ideas/facts?????
 

Brad Little

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I have five Guild Flattops, one for over 50 years, two for over 40, plus have had a few others over the years. Never had this problem.
Brad
 

matsickma

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I had a few Guild acoustics for many years and I never had a crack in the wood but did get finish cracks between the pickguard and neck on a '80 D40CE.
M
 

adorshki

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As gjmalcyon suggests, suspect you've been seeing the effects of the neck block shifting forward as the neck is pulled towards eth bridge by string tension.
Our member Christopher Coad explains thusly, here:
"I have no idea when it occurred, but the dreaded neck block shift had struck this guitar at some point in recent history, splitting the top along one edge of the fingerboard extension from the neck block to the edge of the soundhole. It wasn't grotesque, but it was noticeable, and it identified a larger underlying problem. A neck block should never shift."
AND
" These guitars were constructed without using a fingerboard patch, a thin horizontal strip applied to the backside of the soundboard just behind the transverse brace and extending across the width of the upper bout. Instead, a small block was added at 90° to the neck block, sized to be the width of the fingerboard extension and glued to the underside of the soundboard. While this extra buttressing would counteract the tendency of the fingerboard extension to depress the soundboard, should the neck block ever shift forward it would take that section of the soundboard along with it.
As shown in that article:
F-212-Top-Crack.jpg

BTW I suspect you'll enjoy reading the whole article, here for those that may not be able to use the link I embedded above:
https://www.cozadguitars.com/articles/article-1975-guild-f-212-overhaul.html

:friendly_wink:
 
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davismanLV

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As has been said above, failure of the neck block to support the intense pull of the strings towards the bridge. When it fails then everything starts to shift towards the bridge causing those types of cracks. It's quite a difficult thing to correct, and more expensive than just normal soundboard cracks. Again, as mentioned above, this is from the guitar being subjected to extreme heat or sunlight and the glues holding the neck block let go, and then the collapse begins.
 

Charlie Bernstein

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I'll go along with the neck block theory.

But regarding neck block glue failure, it's interesting that some luthiers avoid Guild neck resets because (they say) the glue is too good.

Go figure.
 

adorshki

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I'll go along with the neck block theory.

But regarding neck block glue failure, it's interesting that some luthiers avoid Guild neck resets because (they say) the glue is too good.

Go figure.

Funny you should mention that, I was just reviewing Mr. Cozad's article on re-setting the neck of an F412 and he addresses that issue very specifically, too.
In past we've seen a number of contributing factors mentioned that support that perception, even though they're most likely the exceptions rather than the rule.
Allow me to quote from here:
https://www.cozadguitars.com/articles/article-1980-guild-f-412-overhaul.html
"Something of an urban legend has developed over the decades regarding a notion that Guild dovetailed guitar necks are somehow generally more difficult to remove than other manufacturer’s dovetailed necks. This has simply not been my experience with these guitars, now spanning more than 4 decades...."
AND
"When properly softened, it is just not that big of a deal to remove the neck. Short of general inexperience, I believe the primary reason for difficulty encountered during dovetail neck removal on Guild guitars may have more to do with improper placement of the steam hole(s) and/or insufficient application of steam/heat than the amount (or even type) of glue used."
 

chazmo

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Just don't confuse yourselves, guys. There are two different things being talked about above. The neck block is set into the guitar's body whereas the neck itself is joined to the neck block later in the assembly process. That neck block shifting slightly over time (due to levered tension on it by the neck) is what's being blamed for the kind of damage shown above that Richard was asking about.
 

Christopher Cozad

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My F-212 (which Al referred to, above), had suffered a crack / split in the soundboard along the "bass" side of the fingerboard extension. The treble side remained intact. Curiosity got the better of me and I had (eventually) removed the soundboard to have a look inside. The split was barely visible along the inside of the soundboard, but was glaringly obvious on the face of the soundboard, running all the way from the binding into the sound hole. All the glue joints were intact. While there is a remote possibility that this instrument suffered some kind of sudden heat stroke that went unnoticed by me (where the glue softened enough for wood to "let go"), I believe the crack is the result of either impact damage (such as a sudden blow to one side that torqued the neck, perhaps while in the case - have you ever witnessed baggage handlers with guitar cases?) or maybe due to the neck block swelling from humidity and taking that portion of the soundboard with it.


In my experience splits such as these always occur along the fingerboard extension (the section of the fingerboard that extends over, and is glued onto, the soundboard). Of particular note is the fact that the Guild neck block is significantly wider (3-3/4") than the fingerboard (2-3/8"). The Spruce soundboard is securely glued to and supported by a block of Mahogany beneath it, while a narrow strip of dense hardwood is glued to the soundboard. The grain direction of the fingerboard and soundboard run the same way (lengthwise down the guitar) with the neck block rotated 90°. The hardwood fingerboard and the softwood soundboard do *not* expand and contract at the same rate, and neck block swells and contracts at a right angle to those two. Subject the guitar to extreme temperature and RH shifts, add 200 pounds of pressure/tension by stringing it up, drop it a time or two (not by me) and, well...

F-212-Diagonal-Bracing.jpg


F-212-Neck-Block-Grain.jpg
 

davismanLV

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So, Christopher, just to clarify, you're saying that the shrinking/expansion of the different woods (hard/soft) where they're glued could cause such a crack and does not necessarily mean that the neck block glue has been compromised. Did I get that right??
 

Christopher Cozad

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..you're saying that the shrinking/expansion of the different woods (hard/soft) where they're glued could cause such a crack and does not necessarily mean that the neck block glue has been compromised...
[Carefully positioning head on chopping block...] Yes, with certainty. The issue of humidity extremes is the enemy of my wooden guitar!

*AND* I believe a severe impact blow, such as occurs when baggage militants callously hurl guitar cases against immoveable objects (old/older style cases, where guitars can slop around inside, especially sideways) could also be a cause of such a crack. Hold your guitar in front of you (eyeing it lovingly, of course, and speaking to it softly, and swearing this will never happen - it's just a visualization) and imagine a sudden, massive force impacting the headstock/neck from one side, all while the body remains relatively motionless...[...TORQUE goes the neck block and CRACK goes the soundboard!...].

Speaking seriously for just a moment, I think this could occur miles away from an airport, where a guitar standing in a case (possibly up against a wall) falls to one side and impacts the floor. I'm not admitting this has ever happened to any guitar I have ever been entrusted with, but I had this friend...

And then there is always the softened glue / string tension / neck block slippage explanation - which really does occur, and is a real problem when it does.
 
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Christopher Cozad

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Or neck block, as it were?
Al, you clever fellow! I felt as though my eyes were glued to your post. I thought, 'Well, tan my hide! I am braced for impact, even if I have bored them soundly. I am back!' And then I felt as if my sides wood burst for laughing. ;~}
 

davismanLV

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HAAAAAA HAAAAA!! Love ya, Christopher (and Al) !! Thanks for making me laugh out loud tonight. So yeah, I get you. Mostly. Does anybody really know what time it is???

So yeah, trauma, abuse, heat, lousy packing and loose cases and that's even BEFORE we get to the damn train station...... :witless::witless:
 

Nuuska

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Chritopher

How often guitar luthiers open the back of the guitar to examine whats wrong with the top?
I had a good friend who was violin repair man. Visiting his shop I often saw instruments opened from back so he could repair top.

Seems that especially with a guitar that would be so much easier. No need to remove neck etc. Naturally things are different, if neck reset is decided.
Just never saw a picture like that.
 

Christopher Cozad

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Hei Nuuska!


Both the front and back plates of the typical steel string acoustic guitar are designed as independent components that glue to a small ledge (kerfed or solid lining) along the outermost rims of the sides. Removing either of those plates is pretty straightforward, as you simply cut through the binding, side wood and linings. Care must be taken to remove the plate from the neck and heel block. The project involves aesthetics more than anything else. After the plate is reinstalled you must completely replace the binding you cut through and touch up the finish.


You can certainly remove the back plate to gain access inside, and this can be a very effective way to adjust (or "tune") the bracing. There can be a complication: The neck heel of most acoustic guitars often terminates just past the point you would be removing. It is fitted, glued and finished in such a way that it makes/can make it quite messy to remove a back (let alone, reinstall the back) without first removing the neck. Of course, once you have the neck off, taking off the back or the front is the same work.


In my case, I had already determined to replace the soundboard, so I was removing the old one anyway.
 

Nuuska

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Thank You Sir

So nice - on this forum one can learn a lot. :watermelon:
 

fronobulax

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A shout out to Christopher and Al for a sequence of posts that were simultaneously informative and creatively funny. Thanks.
 
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