Official Luthiers Forum!
http://mowrystrings.luthiersforum.com/forum/

split brace. what to do.?
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=13885		 Page 1 of 1
Author:  gratay [ Wed Oct 03, 2007 4:36 pm ]
Post subject: 
while tuning my top I have just discovered the upper transverse graft has a hairline split from one end of the brace.
It is about 3/4" long and goes right through the thickness of the brace which is about 2.5 - 3mm.

My shop only fluctuates around 10% RH. Don't know if this may be the cause or the fact that I carved the braces on my benchtop and not with it being supported in the dish.

I'm wondering if I just spray a bit of water on it and run some titebond into the crack it that it may be alright?

what do you guys think?

cheers for any advice
grant
Author:  Shawn [ Wed Oct 03, 2007 5:09 pm ]
Post subject: 
If the top is not installed I would take out the brace and replace it. IF there is any runout at all in the brace, while ti could be repaired, the brace could crack in the future in some other portion.

I am sure that others will say that it is okay but because the braces are so critical to the support and vibration of the top, any fault will ultimately affect other factors in the guitar. If the top is installed, then it is another matter all together...then it is probably easier to just repair.

Did you split the braces or saw them? The good thing is that braces in the uper bout are almost completely for structural support but if there is runout in that brace and the braces were not split there could be runout in others. As long as the others look like there is no runout and are intact you should be okay.

Lastly, gluing when the humidity is low is a recipe for glue joint failures...if your humidity is low you can raise it by using a number of large open pans of water with a fan blowing over them to raise the humidity. In most cases gluing with the humidity too high is safer than gluing when the humidity is too low.

Usually if the variation in humidity is within 10-15 percent you should be fine but if that relative humidity is below 40 percent or above 55 percent then you are going to have issues and different ones based on the change of seasons.
Author:  Dave Rickard [ Thu Oct 04, 2007 5:43 am ]
Post subject: 
If it were me I would replace it. No need to take qa chance if you don't have to.
Author:  Mike Mahar [ Thu Oct 04, 2007 6:00 am ]
Post subject: 
[QUOTE=Shawn]
Lastly, gluing when the humidity is low is a recipe for glue joint failures...if your humidity is low you can raise it by using a number of large open pans of water with a fan blowing over them to raise the humidity. In most cases gluing with the humidity too high is safer than gluing when the humidity is too low.

[/QUOTE]
This is just the opposite of my experience. If I glue with the humidity too low, I get a top that bulges in humid conditions. If I glue with the humidity too high, however, I get a cracked top.
Author:  gratay [ Fri Oct 05, 2007 2:50 pm ]
Post subject: 
[QUOTE=Shawn]
Did you split the braces or saw them? The good thing is that braces in the uper bout are almost completely for structural support but if there is runout in that brace and the braces were not split there could be runout in others. As long as the others look like there is no runout and are intact you should be okay.

[/QUOTE]
no i didn't split the braces , they we're sawn.
i guess i don't understand the merits of splitting the brace wood since you still have to plane up to spec anyway i decided to saw instead.
maybe i'm learning the hard way.?
Author:  Mattia Valente [ Sat Oct 06, 2007 7:30 am ]
Post subject: 
You split the billet, so you have one runout-free face, and saw all individual braces from there. You split perpendicular to the quartered face, not along the growth rings. One split per billet required, the rest is sawing/planing/sanding/whatever.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/