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You know you are having a bad day when this happens!
This is one of my student's guitars and the thing is just fighting him from start to finish!
I will post pics later of the repair.

Sometimes wood just does whatever it darn well pleases. I'm sure the repair will be fine with your guidance.

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Humm and it is not even African Crackwood you'r right this is the definition of a bad day

Robbie,

That must have been awful for your student! What brought it on?

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now known around here as Pat Foster
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we noticed a small crack at the waist when we were ready to glue up the top and back. The glue up was put on hold and then as we were trying to remove it from the form to repair the small crack the stress was increased or released and it just did what it wanted to do. It is a clean break with the grain so it should repair nicely but it sure gets your attention.   

I hate it when that happens. Better now then later....

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Joe Beaver
Maker of Sawdust

Ah Man, i hurt with this guy, he's lucky he has you there to guide him on the repair Robbie.

This would be a great tutorial for the newer builders on the forum. If you and studend don't mind could you document this repair with potos and text and post it?MichaelP38782.7037615741

This is the definition of why we use side braces I feel for the big guy. Hope it heals well.
Tracy

Umm...what's with the back braces attached without the back????? Now that just doesn't look right!

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OH - The Pain!   

That's EIR right? I have bent an already cracked side for practice and that crack hasn't spread.

The crack started in the waist? I would be very interested in finding out how this crack got started to avoid one myself. (I wonder whether sides weren't bent enuff - as in they had to be forced into the mold?)

And- HOW would you repair it? I have in mind just putting back in the mold with some wax paper for release and clamp the join from top to bottom - but, would anything more be necessary? What kind of glue?

TIA - I endeavor to learn from the experience of others.   

I will try and remember to get some more pics of it. We have already glued it back together but I haven't got a pic of that. Maybe I could just explain it. We used fish glue on the cracked area. CA glue tends to leave a white line if accelerator is used. Since this was quite a large break I decided that either hide or fish glue would make it less visible when all is said and done. I just happened to have the fish glue handy so that is what I used. I made several small clamping blocks and put one on the inside of the guitar side and one on the outside of the guitar side and then used a cam clamp to align the crack. I did this in several areas all the way along the cracked side. I then used cam clamps on the top and bottom of the side to close the cracked area. It seemed to work pretty well. In the areas in between the clamps my student installed a few side braces. This whole mouse trap is up at the school. I will try and remember to take some pics of it clamped up before we remove the clamps. After a little sanding and scraping it should be as good as new again.      

on my classical guitars I install the back braces into the kerfing by 6mm. so they are actually below the binding line and do not go through the sides but just up to them. I do the opposite on my steel string guitars.

[QUOTE=Don Williams] Umm...what's with the back braces attached without the back????? Now that just doesn't look right!
[/QUOTE]

Yeah looks a bit unorthodox... but Torres at one stage built up his sides and top and then fitted the back braces before fitting the back.

See Courtnall's book "Making master Guitars" for details.

Cheers Martin

[QUOTE=Robbie O'Brien] on my classical guitars I install the back braces into the kerfing by 6mm. so they are actually below the binding line and do not go through the sides but just up to them. I do the opposite on my steel string guitars. [/QUOTE]

I do this for both all my guitars. Some references recommend cutting through both kering and side to house back braces but for some reason Ive never been comfortable sawing into my sides.

I trim my back braces to circa 4mm. I then remove sections of kerfed lining and glue in sections of new kerfed lining offset to accomodate back brace ends.

Cheers Martin

Robbie,
I'd sure like to know what kind of wood that is. EIR, Malaysian blackwood?
I love Malaysian blackwood, but the stuff splits just looking at it, and at
the prices you pay for the stuff, it's not worth the risk anymore.
Craig

This is EIR from an LMI kit. The wood really is good quality stuff. I have the feeling that somehow this happened in the handling of the guitar and form during the building process. Just a minor set back though and in no time we will be making progress again.    

I said I would post pics of the repair for the sides cracking.



This shows how we clamped the sides together to align them and close the crack.

Here are the shots after removing the clamps and cleaning up the side with a scraper and sandpaper.
good as new!

Great job, Robbie.
That student has learned far more with this experience than building alone would have taught him.

SteveSteve Kinnaird38785.4954398148

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Super repair. I had an Indian Rosewood crack about ten inches. It was in the mold and another mold fell over into the sides cracking it. First time I used side braces, now it's just standard procedure for me. I used Hide Glue on mine and just as this it's imperceptible. Great job, kudos to you and your student Robbie.

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Hmmm...

I wonder if this might have been the scenario: The sides had some springback forces at work while in the form. Those forces were unleashed on removal and the back edge of the sides were held in place while the top edge was more free to move by not having braces to restrict them. The top edges moved, the back edges didn't. Just speculation. Does this seem plausible?

Glad it all came out so well.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

I would think it is more likly the an expansion issue than spring back.

The crack was there before removing it and once removed from the form, either spring back or expansion or whatever you want to call it along with trying to align the small crack caused the crack to worsen. Normally at this point the guitar is not removed from the form but we had no choice. It was a great learning experience for the class in repair work.

Nice repair, now add side braces, side braces wouldn't have stopped the crack but it sure would have reduced it.