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PostPosted: Mon Jul 03, 2006 3:05 pm 
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Mahogany
Mahogany

Joined: Sat Jan 21, 2006 1:53 pm
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Anyone tucking their brace ends under the X-brace on tops (and non-traditional backs)???

I didn't do it on my 1st (which is still in work) and I am now wondering if I should have...OR...if I should be reinforcing these areas with cloth or a spruce cap to compensate for the lack of tucked ends.

I understand the tucked braces should be better since they have a more "positive" load and sound transfer than the butt joint that I currently have.

The Cumpliano & Natelson book (guitar making) did not address tucked braces, but, my plans from Martin clearly show it (I guess I missed it on the plans since I am really building from the cumplaino book less the building board (I like my external mold).

Anythoughts...re-inforce my braces...leave them alone...let me know what you think.

Thanks again,
JP


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PostPosted: Mon Jul 03, 2006 3:10 pm 
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Brazilian Rosewood
Brazilian Rosewood

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JP, i'm not as experienced as others but i just butted mine against the X brace on my first and on my second and both tops are responding well so far, i'd say leave it like that unless others bring you some more food for thought!


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PostPosted: Mon Jul 03, 2006 3:18 pm 
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Koa
Koa

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On the top, the only braces that I tuck are the x braces and the upper brace under the kerfing. On the back I tuck all four.

Al


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PostPosted: Mon Jul 03, 2006 4:25 pm 
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Koa
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Location: Olympia
First name: Mark
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JP:

I found this thread in the archives. It has a pretty complete discussion on it. As for myself, I don't tuck any other braces into the X-Braces...

-Mark

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PostPosted: Mon Jul 03, 2006 4:28 pm 
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Cocobolo
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JP
I assume you mean the tone bars (or lower face braces)where they meet the X and also where the finger braces meet the X and the bridge plate into the X. I have never done it on the 30 or so flat tops I have built. I do fit the ends well to the places mentioned and don't leave them hanging out from those areas as I have seen some big manufacturers do. The only place I have ever noticed any mention of them being "tucked" is the Martin Plans also the Stew Mac plan of the Herringbone Dreadnaught by Don MacRostie. I get lots of comments on how responsive and well balanced my guitars are, soooo appears to be no negative affect. It seems as though tucking the braces may stiffen up the top or couple the braces together better..maybe

hope this helps more than it confuses
Davebertoncini38902.0961342593


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PostPosted: Mon Jul 03, 2006 9:27 pm 
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Contributing Member
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It seems to me that the top and braces function as a unit in any guitar. The parts are glued together (think "fused"), so they are not "parts" any more. Tucking braces under the X may have some effect, but I don't think the braces are really more "coupled" than they already are just by being glued to the top.

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PostPosted: Mon Jul 03, 2006 9:58 pm 
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One rule of thumb is that any brace that is not tucked under another brace (or lining) must be thinned down to nothing so it flexes with the top's movement or it can come unglued following humidity changes or sudden blows. Some guitars also have the bridge plate tucked under the X-braces to follow this logic (which also makes them more difficult to remove should that become necessary).

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PostPosted: Mon Jul 03, 2006 10:25 pm 
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Brazilian Rosewood
Brazilian Rosewood

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Good points guys, a bit of glue at the edges of the butt joint between the bridge plate and the X brace and this area should be well done.


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PostPosted: Mon Jul 03, 2006 11:00 pm 
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Koa
Koa

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     Tucking was done as glues were weaker than what we have today. There are some that tuck and that is fine. I don't see any advatage to it with todays glues.
     john hall


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PostPosted: Tue Jul 04, 2006 7:27 am 
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Brazilian Rosewood
Brazilian Rosewood

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tippie53:

Hide glue is in no way inferior to any 'modern' glue in terms of peel strength, and may be better, when it's used properly. Some of the 'new and improved' glues, like polyurethane, seem to be particularly bad in that respect. Since tucking the braces is, IMO, more a structural than an acoustic thing I'd follow the rule that Arnt stated with any glue.

Of course, the way you taper the braces has a lot to do with tone, but the idea is to taper them 'right' for sound and tuck the ones that have to be tucked. Since you sometimes don't know in advance what the brace ends will look like by the time you've carved them down, it's just a good idea to tuck things in. Except the bridge plate.


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PostPosted: Tue Jul 04, 2006 2:11 pm 
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Old Growth Brazilian
Old Growth Brazilian

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If you end the brace at near zero left at the end of a taper then I see no need to tuck finger or tone bars into the x. If you but flush without inleting them into the ajoining member then you can haver issues do to expansion because the grains will be running skewed to each other. Ending with an edge at the end but short of contact, I have been told creates a stress riser and can lead to brace and plate seperation later down the road.MichaelP38902.9681018519


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 Post subject:
PostPosted: Tue Jul 04, 2006 11:44 pm 
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Koa
Koa

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Location: United States
   I agree strucurally that tucking is stronger. Alan Carruth's been doing this a long time and his knowlege is superior to mine.
   Is it neccesary I don't think so but I agree tucking will be stronger.
john hall


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 Post subject:
PostPosted: Wed Jul 05, 2006 2:56 pm 
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Mahogany
Mahogany

Joined: Sat Jan 21, 2006 1:53 pm
Posts: 68
Thanks again for all the great discussion...

I'm too far gone to tuck now...but...I'll be doing it on build #2 (where applicable).

Hesh...regarding the butt joint comment tucked or untucked...I believe your right about the joint.

However, the tuck would be stronger as the glue joint is loaded in compression when the strings are tightend.

The x-braces all pulled up toward the top effectively pinching the ends of the tucked brace...

An untucked brace conventionally joined to the x-brace through a butt joint would have a glue joint placed into shear (which I believe would be the weaker based on the load path).

Just my thought at this point...BUT...I guess I got my question answered...IF I leave my untucked joints alone without cloth re-inforcement, I'll mostlikely be fine and the top won't implode on me...

Right???...by the way....I still believe...I really do...believe....

Thanks again,
JP


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