Dupont crack Repair Help!

Bob Holo · December 2011

That's a... really weird... crack. It looks like it's just splitting at all directions to the grain. I thought at first it looked like an impact split, but looking closely at the picture it just seems to be separating.

I'm not sure how Dupont does their laminating so I can't assess if this is structural or just visual. Perhaps an inspection by a local tech will reveal if the inner layers of veneer are intact. But something is shrinking relative to something else. the layer of veneer under that one probably runs cross-grain, so it is not shrinking at the same rate in that direction.

It's tough to tell what's going on, but severe temp & humidity changes can do some strange things to wood, and the first place you're going to see problems will be bonds between differently oriented material and/or end-grain... this spot has both of those, so I guess it makes sense it would be the place to give first. This looks like Morado. It's not a notably "splitty" wood - there must have been some pretty amazing pressure to rip it open like that.

My recommendation is to quit whichever company stationed you in Antarctica and go back to France. ;-) If you freeze your guitar you can always buy a new one. But if you freeze your ass off, you can't just buy a new one of those.

frater · December 2011

Bob Holo wrote:

My recommendation is to quit whichever company stationed you in Antarctica and go back to France. ;-) If you freeze your guitar you can always buy a new one. But if you freeze your ass off, you can't just buy a new one of those.

Not sure about that Bob. With recession hitting hard we'll probably see a lot of people willing to sell soon...

killynonis · December 2011

Have you checked the inside of the guitar?
If the crack is the same , the guitar had being knocked somehow, and nothing to do with humidity or lamination.

frater · December 2011

That is something that crossed my mind too: I did exactly the same damage to a classical Juan Estruch knocking it down when I was a boy...

marcos81 · December 2011

Well its day 3! And the sponge trick helped out a little bit. the crack doesn't look so dry as it once did. I tightened the strings to standard tuning and played the guitar. The action is definitely lower than before. I can still hear a clean note on frets but it sounds like the guitar has a built in mute. The guitar is not as bright and whole sounding as before. I also own a gitane GD255 and this guitar was exposed to the same air the dupont was. The gitane right now is unplayable. There is fret buzz from the 14th fret to the 1st. Only an open string is clear. I hope that the damage done to the gitane isn't an example of what is to come to the Dupont. I travel to the local Busan guitar store in the morning to find out my options and possibly find a humidifier instead of waiting. ........Oh but the guitar has never been knocked over, It's only been in my possession a short while and would remember dropping this expensive guitar over.

frater · December 2011

So if also the Gitane shows the same problems it's definitely a humidity issue. Watch out for the tops, cracks there are far more dangerous (and yes, you need another humidifier for the 255!).

richter4208 · December 2011

That's why you keep tension on your strings at all times. Now yo need to adjust your truss rod as it has relaxed. You'll want to increase the bow a bit. A couple small partial turns on the truss rod, and make sure you know which way to turn!

J

Jazzaferri · December 2011

My Dunn Ultrafox got a crack in the curve in the lower bout table side about the same distance from the top that best guess is the tension of a week in the prairies created the stress and a bang on the side started the crack

Michael fixed it ok and can't see the crack anymore

klaatu · December 2011

Whoa, let's slow down here. Don't go messing with the truss rod just yet. Frater is right, what you're describing is symptomatic of a dried-out guitar. The top will sink, causing the strings to go flat, and in extreme cases, fret buzz will result.

Let's start by humidifying both guitars for several days. I would err on the safe side and refill the humidifiers daily in the beginning. That should get the tops back up closer to where they belong.

Then, check the neck relief. Most people prefer to have a very slight dip in the neck about midway. Here's how you check it:

- Put a capo on top of the 1st fret. Right on top, not between the frets.

- Press the low E string down on top of the 14th fret. (For guitars with 12 fret neck joins, you go with the 12th & 6th frets)

- Check the gap between the string and the 7th fret. If you can get hold of some feeler gauges, somewhere between .008"- .012" should be about right, higher for hard pickers. If you don't have gauges, then check to see if there is a little daylight showing between the string and the 7th fret. A lot of daylight, it is too bowed. No daylight, the neck is too straight or bowed in the wrong direction.

You can do the same thing with a straightedge if you have one long enough, but this method creates a straightedge out of the string.

If the relief is OK, then leave the truss rod alone. If it requires adjustment, I'd suggest looking up "truss rod adjustment" on the Internet and following the instructions very carefully. It's not something to be afraid of, but carelessness or over-zealousness can lead to a broken truss rod, which is very nasty. If you're not confident about doing this yourself, then get a qualified guitar tech to do it. Your Dupont probably came with a truss rod wrench which works for it, but it may not fit the Gitane, and finding the right size wrench can be tricky, especially for oval holes.

After the top has been well humidified, and if the neck relief checks out OK, then check your action. Action adjustments are done at the bridge, not with the truss rod.