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Ugh, X Brace Issues
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=12216		 Page 1 of 1
Author:  blindreality [ Tue May 29, 2007 4:49 am ]
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Oh the joys of building one's first anything...


I think I've messed up my Xbrace. I'm building a dread from the LMI plans and after I put on my xbrace I then pulled out the calipers and measured. Dumb, but that is what I did. 10mm at the center (2mm short of the plan's design. The braces have tapered ends and are curved on the top. I'd show pics, but I'm at work.


I have three thoughts. I could try and remove the brace. I could plane out the brace flat and build it up, or leave it.


So I'm looking for opinions. What would be the consequences of leaving it as is? Less strength?  They seem fairly thick compared to a lot of what I've seen on the forum. I'm just interested in making something that sounds decent and to learn from it, but I do want it to sound decent. I can post pics tonight if someone wants to see them.

Author:  Rod True [ Tue May 29, 2007 5:04 am ]
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Jared, are you saying that the brace is 10mm (3/8") HIGH?? If you are talking about them being 10mm wide (which I sort of doubt) than I'd say they are to wide and you could take them down.

That sure is a low brace, for a dread for sure to low. You need the height to ensure the strength of the brace.

Personally, I would remove the braces, make new ones (9/16" high) and put those on.

Laminating a new piece on top would make it stronger, but not as strong as if it were one solid piece. The glue join will see a shear load and will want to separate once loaded. You want that solid piece.

Make it right and you won't regret it.
Author:  blindreality [ Tue May 29, 2007 5:14 am ]
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Yes, 10mm high... 8mm wide.


Chisle them out I suppose? Tips? Lets just say it has been a frustrating weekend.

Author:  burbank [ Tue May 29, 2007 5:25 am ]
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Jared,

This is something that most everyone here has experienced or will experience or is it just you and me?

Yup, chisels. Very sharp ones. Work slowly when you get close to the top. Make sure you get rid of the glue on the top, otherwise you won't get a good bond (unless you used hide glue first time around). Spend as much time as needed so you have a clean, smooth surface when you're done, which will get you a good bond for Braces version 2. You don't want the top pulling away from the brace.

It's a setback, but go slow, be careful. You'll be fine.
Author:  Steve Saville [ Tue May 29, 2007 6:52 am ]
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[QUOTE=Rod True] ......Personally, I would remove the braces, make new ones (9/16" high) and put those on......[/QUOTE]I agree.

[QUOTE=blindreality]

Yes, 10mm high... 8mm wide.


Chisle them out I suppose? Tips? Lets just say it has been a frustrating weekend.

[/QUOTE] You'll be pleasantly surprised how easy they come off with a sharp chisel. (Don't ask me how I know!     )
Be sure to sand/scrape almost all the old glue off. HHG and epoxies are great for re-gluing, but Titebond, AR, and LMI white glues will not bond very strong the second time unless the old glue is removed.
Author:  crazymanmichael [ Tue May 29, 2007 8:03 am ]
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i'm not familiar with the lmi plan but if i read your post correctly you say it only calls for a 12mm high x brace at its intersection? that is low by most standards. what width did it call for?

in any event, 10mm, 3/8", is too low for my taste and i agree with those who recommend removing it and rebracing.

Author:  j.Brown [ Tue May 29, 2007 10:51 am ]
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what a great jig!
Author:  SimonF [ Tue May 29, 2007 12:13 pm ]
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I want to re-emphasize the point Steve made. Be very careful to remove
all the glue, especially if it is Titebond or LMII's white glue. You want a
really good glue joint for your soundboard bracing.

Best of Luck,
Simon
Author:  blindreality [ Wed May 30, 2007 12:49 am ]
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Well, I gave my chisel and my nerves a good workout last night and removed the xbrace. I got probably 98% of the glue up and along with it more wood than I cared for. There is no discoloration in the path of the xbrace. I did damage some wood, but only a few nicks and a little tear out that came up with some of the glue. Would you recommend putting a little glue in those areas after I get the braces on or just leave it as is.


I read before I started making this thing that it is both frustrating and rewarding. I've found the frustrating side of things.

Author:  crazymanmichael [ Wed May 30, 2007 1:25 am ]
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wood glues do not provide gap filling strength so filling with glue is relatively useless.

but do try to get all the old glue residue off. try wetting with naphta; it should show up the residue. a small scraper or a sinble edge razor blade with corners rounded an a hook turned works well. the back edge of a sharp chisel also scrapes well.

any glue residue left behind will result in a weaker join.
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