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I have fixed big cracks before. I removed the back, and removed all braces, closed the crack (after that back has had time to acclimate to 45% RH), reglue the brace, and cleat it if necessary. That was on an old Stella copy (Not Stella, possibly Galliano or something)

If you want to save the wood, you will need to remove the back and acclimate it to a standard RH (45%) and brace it under that condition, after fixing the crack of course. The back will most likely have shrunk and it will NOT grow back (it was said wood that shrunk due to low RH doesn't really grow back) so you will have to trim your braces to fit before gluing that back on. If you are unable to close the crack after removing the back, you will have to fill the void by inlaying the same wood into it.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

So, I finally got around to fixing this thing. I was dreading it (no pun intended), but I had a little time and figured it had been long enough. The back came off without too much trouble.



I found a piece of bloodwood that had really straight grain. Since I currently only have a bandsaw that will barely resaw a 6 inch piece of wood I made a three piece back out of it. Because the joints are so tight, it almost looks like a one piece.







Glued up the same way I did the original.






When I first got the new back on I wondered if it was as good as the old back in sound. When I first tapped the instrument it didn't have a very inspiring sound to it. After attaching the bindings and getting everything sealed up so I didn't have a bunch of tiny little vent holes from the kerfing, it started to sound right.

This whole build has been a great lesson not only in relative humidity while building but also in the role the back plays in the overall sound of the instrument. I got to hear it when it was first put together, with that nasty crack all the way up the back, without a back, with a back and a bunch of little holes from the kerfing, and finally sealed up with bindings and all.

Thanks to everyone for all your help. On to the next one.

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"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Sweet. I love seeing a follow up post to a problem like this. Thanks for updating us. It gives courage to the next guy who has a boo-boo that needs some major re-doing.

Your finished guitar looks great. Cheers!

Yeah closing the little binding holes makes all the difference in the world doesn't it. That back looks great. So did the original one but oh well that's the way it goes.

Aaron, I can see in your repair photos that the garage door is open and it appears to be fair, warm weather outside. If very recently done, then it's probably HOT outside...and very humid. You're going to take that guitar indoors and your house is going to dry out this winter when your central heating system gets active. Ergo, the same thing could happen to you all over again. You've probably replaced the back in 70-80-90% humidity. This coming January, your indoor humidity will be pretty much what it was last January. See what I mean?

For that reason, I recommend storing this guitar in a nice case with a humidifier inside and with the case lid closed. Sure, you get it out as often as you wish to play it. Even if you're not playing it, you open the case every day or two to let the air exchange.... but you always store it in the closed case with a humidifier. Don't put it on a guitar stand in the living room corner this winter or you'll be risking another crack.

When you build the next one, please try to do all your cross-grain glue ups (bracing, box closing, etc.) in lower humidity.
Maybe you can rig up a glue station in your furnace room or in a utility room that is heated. Do your gluing in the winter months. You'll have to wait for a fair, warmish day to do your finish work outside, but you'll get an occasional day where the humidity is okay for that. Best of luck with all that.

By the way, I haven't told you yet that I think this is a very pretty guitar. Nice job!

Thanks. Actually... I checked the humidity and it was right around 50% at the time I did all of the glue ups.

I normally keep my eye on the humidity since here in Atlanta it can get outrageous. I have to stay on top of it to know which days are good for finishing and which days are not. I have slowly gravitated toward a schedule where I plan on doing things like fretwork, wet sanding, buffing etc. on high humidity days. I even go so far as to mark on my calendar which days are good candidates for finishing.

My next task will be to get some lacquer on this thing. I'm guessing that may help make the guitar less sensitive to environmental changes. I know for sure it's going to make it look fantastic.

I've never used a humidifier in an acoustic guitar. I don't know that I've ever owned an acoustic guitar where it really mattered. What I've learned is that every acoustic I have ever owned has been built for structure and not tone.

Is there a good product I should look into?

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"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Thanks!

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"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Hi, again, Aaron.
Finishes are a very personal thing, so I can't advise too much on that. I've used nitrocellulose as well as waterborne and even spar varnish on various instruments. I haven't yet done a French polish but I've got a thin layer of shellac under all but two of my finishes. I think someone with more experience than I have should advise you about finishes. However, if you can be patient and wait for some more days of 50% humidity (or less) and 70 degree temps, you could probably apply just about anything you wish to your guitar.

Please remember what I said about getting a guitar humidifier and a nice case for the coming winter when your house will dry out. If you do that, you will most likely be okay.

In my opinion, you have done a fine job with the first build (except for the back issue, which might have been relative humidity or a still-wet piece of wood) and a fine save on the second go-around, as well. I am really rooting for you on this one. It's a very nice looking instrument and I'm glad you didn't smash it!

Press on, and best of luck to you. Let us know how it come out!

Was your wood stored in a low humidity environment prior to gluing? If the wood is subject to high humidity for several days prior to gluing, it should have some time in low humidity to give it a chance to adjust.

My wood gets stored on a shelf in my shop. Unfortunately, I don't have the option of controlling humidity.

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"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Humidity control is VERY important. I found that out the hard way on my first guitar. Those thin boards are affected by humidity a lot more than thicker boards (such as for guitar necks or solid body blanks) and therefore while humidity control may be optional in building solid body guitars, it is essential when building acoustic guitars unless the humidity in your region never changes and you never intend to move the guitar anywhere else.

If you can't afford to humidity control your entire shop (let's face it, for people who lives in constant high humidity regions such as SE Texas, Florida, Taiwan, etc. it gets very expensive) at least find a small room to store your stuff in, and humidity control that room. You can then set your go bar decks in that room and do all your gluing operations in that room. I do that and it works for me so far.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com