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Salvaging a split brace
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=15922		 Page 1 of 1
Author:  Wes McMillian [ Fri Feb 15, 2008 12:27 pm ]
Post subject:  Salvaging a split brace
Right as I was finishing up carving the X for this OM, the brace split out toward the end of the upper leg of the X. This was one of those moments when I knew I should stop and come from the other end but didn't listen to that inner voice. [headinwall]

Deal is, the split terminates just shy of where the linings will be. I feel fairly confident that I can wick some glue back in and clamp it, but wanted to know what you guys think before I go any further. I know this is a major structural member, but as long as I can get some glue back in the joint, it should be at least as strong as before, right?

BTW, everything was glued up with HHG. I wonder if I can thin HHG enough to work in the crack (the crack opens up cleanly by flexing the soundboard here), or if CA would be acceptable?
Author:  grumpy [ Fri Feb 15, 2008 12:29 pm ]
Post subject:  Re: Salvaging a split brace
C'mon.... It's a brace. Costs nothing to replace at this time.

Chisel it off and replace it.
Author:  Colin S [ Fri Feb 15, 2008 12:30 pm ]
Post subject:  Re: Salvaging a split brace
My view, scrap it start again, it's just a bit of brace wood that hasn't been glued down to anything, why start with a repaired piece of wood?

Colin
Author:  Hesh [ Fri Feb 15, 2008 12:33 pm ]
Post subject:  Re: Salvaging a split brace
Rick has a trick where he injects hot water first and then injects HHG - the hot water helps the glue permeate better. This looks like a good place to use Rick's idea. I would move the chair first though so you don't glue your top to it...... ;) :lol:
Author:  WaddyThomson [ Fri Feb 15, 2008 12:38 pm ]
Post subject:  Re: Salvaging a split brace
I'm thinking, if it split that easily, it wasn't a good brace anyway. I'd replace it with another. I re-carved 2 of 3 because I didn't like them. If you haven't stuck it to anything, start over.
Author:  Michael Dale Payne [ Fri Feb 15, 2008 12:50 pm ]
Post subject:  Re: Salvaging a split brace
The only acceptable time to fix a split brace is on a closed instrument that you would be unable to replace without causing more trouble that its worth.

Make a new one [:Y:]
Author:  Bill Greene [ Fri Feb 15, 2008 1:17 pm ]
Post subject:  Re: Salvaging a split brace
Replace. I had to do it on my first top, and it wasn't a big deal. Took more time to resand than anything else.
Author:  Wes McMillian [ Fri Feb 15, 2008 2:24 pm ]
Post subject:  Re: Salvaging a split brace
I was afraid that would be the consensus. I just hate having to chisel off the entire X for this one split. It was a sweet fit, too...

So, OK, I concede. It'll come off. But, for the sake of argument, don't we usually consider a properly glued joint as strong as, or usually stronger, than the surrounding wood?
Author:  Michael Dale Payne [ Fri Feb 15, 2008 2:37 pm ]
Post subject:  Re: Salvaging a split brace
westex93 wrote:
I was afraid that would be the consensus. I just hate having to chisel off the entire X for this one split. It was a sweet fit, too...

So, OK, I concede. It'll come off. But, for the sake of argument, don't we usually consider a properly glued joint as strong as, or usually stronger, than the surrounding wood?


There is no doubt the glued joint would be stronger in shear strength at the repair than the wood was to begin with.

The thing that makes this not the right thing to do is by adding the glue joint you are reducing by some margin the effective energy transfer through that brace.

Question: If you were holding the brace in your hand to take the picture. Why would you have to carve off anything?

never mind I see the picture clearer now
Author:  Wes McMillian [ Fri Feb 15, 2008 2:43 pm ]
Post subject:  Re: Salvaging a split brace
It may not be clear, Michael, but the pic is of the braced top. I was doing some final tapering of the upper legs of the glued X when it happened. I held it against the rim and, sure 'nuff, the split falls just short of the linings but not by much. I'm purposely flexing the top a little at the edge in the pic. It closes up nicely with finger pressure.
Author:  Michael Dale Payne [ Fri Feb 15, 2008 2:46 pm ]
Post subject:  Re: Salvaging a split brace
I saw when I looked back at the picture. If me I would still carve off. Besides I would give me a chance to cave some bore braces :D (oboy oboy oboy [clap] [clap] )
Author:  Barry Daniels [ Fri Feb 15, 2008 2:55 pm ]
Post subject:  Re: Salvaging a split brace
Looks like some serious grain runout in that brace, which is another good reason to replace it.
Author:  Hesh [ Fri Feb 15, 2008 3:11 pm ]
Post subject:  Re: Salvaging a split brace
BarryDaniels wrote:
Looks like some serious grain runout in that brace, which is another good reason to replace it.


Now that is a reason that I will buy - thanks Barry. But yes, a good glue joint is going to be stronger then the wood around it.

As for a glue joint that can be at the molecular level like a good collagen glue i.e. HHG, FG damping vibration transfer remember that these braces are glued to the top with glues like HHG and FG. The split is also on the upper X leg where many builders (not all mind you) see little tone potential.
Author:  WaddyThomson [ Fri Feb 15, 2008 3:34 pm ]
Post subject:  Re: Salvaging a split brace
I didn't see that either. Sorry! That is a lot of work.
Author:  Wes McMillian [ Fri Feb 15, 2008 8:06 pm ]
Post subject:  Re: Salvaging a split brace
Yep, I split and dimensioned another set of brace stock this afternoon. Would've got the soundboard stripped and prepped but other things came up. And I'll be working 12's for the next 7-9 days straight, so I won't get back to it for a while. Oh, well. That's the price you pay for a day job...

Thanks for the advice everybody.
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