What causes a crack like this one?? (Full Version)

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Anders Eliasson -> What causes a crack like this one?? (Apr. 11 2012 18:41:43)

Look at the photo. There´s a crack in the headstock. It follows the grain of the cedar but its 90 degrees to the endgrain. Anyone who knows, please tell. Its an easy repair, but I´m curious. I was told that when woods crack along the grain and parallel to the endgrain, the it could be change in humidity and that cracks like this one normally is because of its been hit or dropped.



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TANúñez -> RE: What causes a crack like this one?? (Apr. 11 2012 19:43:27)

I was going say it looks like it was hit or dropped. I developed a similar crack on a guitar once due to it being dropped while in the case by UPS.



Jim Kirby -> RE: What causes a crack like this one?? (Apr. 11 2012 21:52:58)

Seems like it would be an impact injury, as the wood is free to expand or contract with humidity at that point. (Unless it was really not properly dried and is getting an end check?)



Jeff Highland -> RE: What causes a crack like this one?? (Apr. 11 2012 22:11:30)

Hit, dropped, or a defect in the wood prior to use.



Ricardo -> RE: What causes a crack like this one?? (Apr. 11 2012 22:14:13)

aliens.



Turner -> RE: What causes a crack like this one?? (Apr. 11 2012 22:52:12)

quote:

aliens.


If they dropped it, then, probably, yes.

[8|]



aarongreen -> RE: What causes a crack like this one?? (Apr. 12 2012 3:43:45)

looks like a wind check to me . In other words a stress defect in the wood. It happens and often it isnt until way down the road when they show up. Might have occurred as micro fissures in the wood from when the tree was dropped or processed.

If mishandling was the culprit, I'd expect to see some dents in the headstock



Dave K -> RE: What causes a crack like this one?? (Apr. 12 2012 4:10:54)

It seems clear to me (so I'm prob'ly wrong) that the cedar (or Mahogany) neck wood was expanding overall but the expansion was retarded by the denser faceplate wood. The cracking just relieved the tension. Humidity is the culprit... Or maybe aliens... Without the faceplate It wouldn't have cracked.
Cheers, Dave



Anders Eliasson -> RE: What causes a crack like this one?? (Apr. 12 2012 7:00:15)

Aaron If the guitar had been dropped or hit. The impact could have been on the tuning machines and then you wont see a dent.
Also, if it was stress in the wood, wouldnt it be clearer. To me it looks like what happens to a loaf of bread that you twist.

If it was because of humidity, wouldnt the cedar crack all the way down to the headplate?



valerea -> RE: What causes a crack like this one?? (Apr. 12 2012 7:16:42)

If the crack had been caused by a drop on the tuning heads, they may well be bent with the force that caused such an extentsive crack? Are there any marks indicating a droppage?



lowden -> RE: What causes a crack like this one?? (Apr. 12 2012 8:15:43)

This guitar has not been dropped!! You can clearly see from the pics tht there is no signs of damage



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aarongreen -> RE: What causes a crack like this one?? (Apr. 12 2012 11:42:41)

Its a wind check folks. For one thing, it's not one continuous crack, if you look closely. There are two distinct cracks. The crack(s) do not run with the bias of the end grain. If it was due to a shock, you would see damage elsewhere to cause that kind of shearing. I've never seen a humidity crack that does not follow the grain, is not possible. A crack due to normal stresses, follow the path of least resistance and in this case it would be going in the other direction looking at the endgrain.

I've seen these types of shearing cracks in tops, backs and sides as well. Thankfully as I was picking out the wood for the guitar, not once it was done. But it can happen. One more reason why wood , among other things, is a real ball busting bitch at times.

In this case, a little glue and you should be fine.



valerea -> RE: What causes a crack like this one?? (Apr. 12 2012 12:11:54)

So Aaron are you saying it is a poor choice of wood in the first instance?



aarongreen -> RE: What causes a crack like this one?? (Apr. 12 2012 12:35:54)

No I am not saying that at all. Such things often don't present themselves until later, as in this case. We are lucky when they reveal themselves before hand. It's the nature of the beast and in this case an easy and permanent fix that will present no issues once resolved. If people don't like all the curve balls wood can throw at them (and from time to time I certainly feel that way) there are plenty of materials that don't do such things, such as fiberglass, carbon graphite, metal, plastics etc.... :)



keith -> RE: What causes a crack like this one?? (Apr. 12 2012 13:12:05)

hey aaron, even synthetics (fiberglass and plastics) and metal can sometimes throw a curveball albeit less so than wood. i agree with your comments about the selection of wood. i have made close to 500 cejillas and occassionally i will get everything done and drill the peg hole to find some defect in the wood and the peg just does not turn well--the same peg in another piece of wood will work like butter. sometimes it is the peg that is at fault. sadly i have to throw away the wood and the time i spent.



Richard Jernigan -> RE: What causes a crack like this one?? (Apr. 12 2012 15:44:05)

quote:

ORIGINAL: aarongreen
there are plenty of materials that don't do such things, such as fiberglass, carbon graphite, metal, plastics etc.... :)


I owned a fiberglass sailboat with stainless steel rigging in the tropical central Pacific for more than a decade. There's no such thing as trouble-free materials when the ocean is working all day and all night to destroy them.....

RNJ



lowden -> RE: What causes a crack like this one?? (Apr. 12 2012 17:06:07)

So its a wind check. I believe this started as soon as the hollows were made for the tuners, probably hitting a fault in the wood and taking two years to open up.



aarongreen -> RE: What causes a crack like this one?? (Apr. 12 2012 17:23:07)

Hi Keith
Yup sometimes its the old trash bin for such things. This is yet another reason why I like to heat with wood. I talk to my materials sometimes, show them the woodstove...straighten up and fly right or I'll roast marshmellows with you.....


Hi Richard,
I was talking about guitars, not boats! You should probably get a titanium boat if you want it to be less of a problem. :)

Hi Lowden
That is probable as anything I've heard. Wood will keep you on your toes thats for sure. It's not a defect with the guitar, thats for sure and in any case very repairable and it will be like it never ever happened I am sure.



estebanana -> RE: What causes a crack like this one?? (Apr. 12 2012 21:21:44)

Yes I think it looks like wind check too. You never know, those things open up later and you can rap your knuckles on the wood and never hear any defect. That's because it has not opened up yet. Sometimes wind shear, wind check, or whatever you call it looks like smashed wood tissue too, it's easier to spot then.

When this happens on violin bows they catch it while the bow is being made. The stick is rough planed straight and then held over a fire or hot iron and then bent over the makers knee to give it the camber. If you hear it go !POP! or CRACK, it goes into the cracked bow blank drawer. The idea is to find out early in the planing process if the stick will crack so you don't spend too much time on flawed wood.

Guitar necks don't have that bending process to reveal an un-obvious cosmetically flawed wind check so you pick the best you can as you see it.

If you get hide glue deep into the crack with a syringe or small warm application instrument and can clamp it tight shut then the problem is solved. A good glue joint tin there will be pretty strong.

It's also called wind shake, it happens when the wood fractures while the tree is still alive due to being pushed around in storms. Or it can happen when the tree is felled. There is also the possibility that is is natural internal tension in the wood. Usually it gets released when the wood is sawn, but sometimes takes a while to shake out.

I hear wood comes from trees, and trees are organic matter. Hamburgers come from cows, cows produce methane gas. Etc.



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