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X Bracing mess-up
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=10666
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Author:  matttheguy [ Wed Jan 31, 2007 11:50 pm ]
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Hello.  I'm new here, referred to this forum for some expert help on my problem.

I'm just getting into building guitars, and after building my first solid body from scratch, I decided I would attempt to build an acoustic kit, as most of the difficult work is done, and it would give me a sense of what I would be up against.  I decided to order a Stewmac kit, as they've generally been very helpful to me and had excellent products and services.

Long story short, I misread the blueprints for the braces and I installed the X braces on the soundboard backwards.  Instead of having the scalloped end going towards the lower bout and having the braces cross at the high point, the scallops point above the waist, and cross at a low point, as you can see here:


You can see there how the X braces are positioned backwards.  I've been told that this will greatly reduce the strength of the soundboard above the waist, but I wanted to get a second opinion.

Some rough measurements of the braces can be found here.

Some more pictures of the soundboard, the braces, and other parts can be found here.

Thank you for your help, it's greatly appreciated.

Cheers.


Author:  LanceK [ Thu Feb 01, 2007 12:00 am ]
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Hi Matt, welcome to the OLF!
My guess is that you will be fine. The braces above the X still look pretty beefy to me. What are there height? You could always scallop out the lower X legs, so that is a non issue.
The only other option, and what I would probably recommend, is to plane them off and start again. if you need some brace stock let me know....

{EDIT} looking back at it, I think id remove them for sure, the intersection at the X does look a little short.LanceK39114.3349074074

Author:  Dave White [ Thu Feb 01, 2007 12:03 am ]
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Hi Matt,

Welcome to the OLF. Well that's certainly a novel form of bracing I'd get in contact with Stew-Mac and see if they will send you some more X and finger braces, chisel the old ones off carefully and start again. The X intersection is too low. Chisel the old braces off by taking small bits off the top of the brace gradually bringing them down to the top wood without letting the chisel dig into the top. Don't try and lever off the whole braces or chisel off too big sections as the odds are it will crack or damage the top - not a good idea. When the braces are off, sand/scrape the back of the top for the new ones and off you go again.

Not a big deal in the scheme of things. Most goofs are very recoverable from.Dave White39114.3363310185

Author:  tippie53 [ Thu Feb 01, 2007 12:46 am ]
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    I think you would be best to get the braces off. Here is a simple way that you can pull them and may be able to save them. With hot water and dental floss you can try and work that into the glue joint. It is tedious but can get your braces off without damage .
    A hot knife can work to is you have a thin flexible putty knife or palate knife. A candle can heat the knife and this you work under the brace and the heat will loosen the glue. Take your time and you should be fine,
john
you learn more from a failure than you do from a success

Author:  crazymanmichael [ Thu Feb 01, 2007 2:15 am ]
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welcome to the forum, and don't feel bad. just about everyone here has done something equally daft if they are experienced, or are just another day closer to doing it if they aren't.

i agree that it would be better to remove them and rebrace.

unlike john hall(tippie53)in his post immediately above, i would be leary of using a candle as a heat source though as the soot from the flame could get on the blade and contaminate the top.

just take your time and view it as a learning exercise.crazymanmichael39114.4287847222

Author:  Steve Saville [ Thu Feb 01, 2007 2:56 am ]
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Matt,
I've done worse. Do take them off and replace them. You'll learn that it really isn't that hard to do.

One thing you'll want to be careful with is the new glue joint under the braces. New glue does not stick very well to dried glue. You need to be sure to sand the old glue line off, down to wood.

Author:  Louis Freilicher [ Thu Feb 01, 2007 4:47 am ]
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Matt,

If it makes you feel any better I put a bridge on a classical backwards this
week, saddle slot towards the tail block!

As others have recommended I would remove the X and re do the bracing.

Louis

Author:  matttheguy [ Thu Feb 01, 2007 7:50 am ]
Post subject: 

It looks like it's off with the braces, then!

I'll try to weaken the glue, first, as I've removed Titebond from other things, but if it requires any sort of force, I'll just start chiseling them off.

Thank you!


Author:  JohnB [ Thu Feb 01, 2007 9:01 am ]
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Hi Matt,

Are you making the Dred or the 000 kit? I am making the the 000 and it
came with X-bracing for the Dred so i have spares. If by chance you are in
or near London, UK you can have mine.

Best wishes and i'm sure it'll work out well in the end!

john.

Author:  matttheguy [ Thu Feb 01, 2007 10:34 am ]
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Well, I'm near a London.  London, ON is right across the lake, but with all this snow and sub-zero weather, I'm not jumping across any time soon!

But, alas, read this:

Matthew,
Thank you for contacting us.
Removal of the braces is likely the best choice. A heat gun can be used, keep it moving to avoid scorching the wood.
If you find you can't salvage the braces, let us know, we can ship replacements.
Let me know if I can provide further assistance.

Best Regards,

Erick Coleman

Technical Advisor
Stewart-MacDonald

I am making the Dreadnought kit, by the way. Stewmac is always helpful and gracious.



Author:  gozierdt [ Thu Feb 01, 2007 10:50 am ]
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Matt,

If taking off the braces is too hard, from an engineering strength point of view, it would be just as strong to take the X support off the top of the intersection, plane the main braces down level, and glue a top piece (same width as the originals) on each of the braces to bring them up to correct height. Properly done, the glue joint will be stronger than the wood, and nearly invisible. A lot simpler than taking them completely off.

Author:  matttheguy [ Thu Feb 01, 2007 10:53 am ]
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So you're saying to flatten the entire brace and then glue supports where the high points actually should be?

Author:  Arnt Rian [ Thu Feb 01, 2007 11:13 am ]
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If you're not going to save them the fastest method is to chisel them off. Be very careful with heat around the center seam, it can open the joint.   

Author:  Greg [ Fri Feb 02, 2007 3:30 pm ]
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I'd try and shave/scallop them to better shape under the bridge and not remove at all. Then finsh the kit string it up and enjoy the fruit of your labor.

Author:  crowduck [ Sat Feb 03, 2007 5:03 pm ]
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I like Gene's idea the best. Just plane those X braces down flat, glue others on top, then carve/scallop to the correct height and profile. They will be laminated X braces then and probably stronger than the original.

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