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Cracked top on a new build
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=47552		 Page 1 of 1
Author:  bcombs510 [ Thu Mar 31, 2016 4:49 pm ]
Post subject:  Cracked top on a new build
Hello,

I'm am back to working on a Peruvian walnut 00 that I abandoned back around Christmas. I was working on multiple builds at the same time but it was too difficult so I switched to just one build and completed it. I finished last week so now I'm coming back to this one.

I dropped the body on the concrete floor of my shop. It landed square on the butt of the body and the top cracked. At the time that it happened the crack was very tight, barely noticeable. So I worked some hide glue into the crack and set it on the shelf. I just got it down and notice the crack is opened again and more visible than before. I work in my basement and the RH stays between 45 and 50. I guess with spring here the RH went up a bit and the top is squirming around some?

Questions:

1) The attempt with hide glue failed the first time and now the crack is more noticeable. Should I try hide again or something else?

2) Now that the crack is separated more, should I put some cleats inside to stabilize it? If yes, do folks usually use hide glue or CA or ???? for the cleats?

3) Is there any way to clamp this closed?

Image

Thanks!
Brad


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Author:  Rod True [ Thu Mar 31, 2016 6:02 pm ]
Post subject:  Re: Cracked top on a new build
Higher humidity will close cracks so that's not likely your issue.....I'll leave the repair to the experts though. Don't know what I'd do with that one as it's most likely not a humidity issue...
Author:  DennisK [ Thu Mar 31, 2016 6:51 pm ]
Post subject:  Re: Cracked top on a new build
I'd say try again. This is one of the advantages of hide glue, that you can reglue things without needing to clean the old glue out first.

Can you reach that far back with your hand through the soundhole? You really need to be able to press up from below to flex the crack open and suck glue into it. Make sure the crack area is good and warm, and pour a generous amount of glue to be sure there's plenty and that it stays warm. Press up from below and down from above to really work the glue in. Also, add extra water to the glue to make it thin so it will go in more easily.

If you feel like it's no stronger than last time, then cleat it as well. Hide glue is good for cleats. Put water on the outer surface of the cleat as well, to prevent it curling up from the water in the glue.
Author:  bcombs510 [ Thu Mar 31, 2016 7:11 pm ]
Post subject:  Re: Cracked top on a new build
Thanks, Dennis. I will try it again. If I use hide for the cleat, is there a tricky way to clamp it? I have some ideas about using one of the really small spreader jacks I have for ukes. That will probably work, but if you have ideas I'm all ears.

Thanks for the help!

Brad


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Author:  bcombs510 [ Thu Mar 31, 2016 7:12 pm ]
Post subject:  Cracked top on a new build
DennisK wrote:
Can you reach that far back with your hand through the soundhole?.


My wife can. :D She is the one that helped me last time.
Author:  DennisK [ Thu Mar 31, 2016 7:30 pm ]
Post subject:  Re: Cracked top on a new build
bcombs510 wrote:
Thanks, Dennis. I will try it again. If I use hide for the cleat, is there a tricky way to clamp it? I have some ideas about using one of the really small spreader jacks I have for ukes. That will probably work, but if you have ideas I'm all ears.

Nah, just rub it in place to squeeze the glue out and hold it for 20 seconds or so. As soon as the glue gels up it should be stuck down pretty well, and as long as it stays that way until dry, it will make a high strength joint. That's why to use water to prevent curling, which can break the initial glue grab.
Author:  Chuck R [ Fri Apr 01, 2016 6:12 am ]
Post subject:  Re: Cracked top on a new build
A couple of strong magnets could provide some extra insurance if you're worried about the cleat not staying down.
Author:  jfmckenna [ Fri Apr 01, 2016 8:19 am ]
Post subject:  Re: Cracked top on a new build
I like to use magnets for such repairs myself. The problem you may run into however is that you have already built in higher then desirable humidity and have a crack that is open. High humidity should close cracks. So you have a sort of double whammy here, a crack opening in high humidity. If that guitar goes to live in a lower humidity environment then that crack will really want to open up again. At the same time it doesn't look open enough to splint too. So at this point and can't hurt to try and close it again and maybe this time the cleats will keep it closed.

That's a bummer. I had the same thing happen to me once many years ago, about 20 years I'd say. I had a classical guitar in the mold and the whole assembly fell off the bench when I was vacuuming and the hose grabbed it. It fell peg head first and the neck crushed right through the sides. IT was just the hoop but it broke clean through. So I hung that broklen hoop up on a hook in my shop as a constant reminder to be careful! IT hung there for 20 years till one day I looked up at it and thought to myself... That could make and interesting cutout guitar right where the break is. So now it's a guitar :D

Good luck.
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