Beginners question

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Peter Lynch
Wandoo
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Joined: Mon Sep 17, 2018 10:51 pm

Beginners question

Post by Peter Lynch » Sat Jul 24, 2021 5:15 pm

Hi
I am currently building a 00 for fingerstyle playing . Engelmann Spruce / Blackwood
12 fret to the body , 24.9 inch scale
my beginners question is this
Some people notch the lower arms of their crossbraces in the Kerfing and some notch right through the rim and some seem to end the lower arms of their crossbraces about 10mm from the Kerfing .
In this case it seems to me that tension carried by the strings is being held by the glued rim of the soundboard . How does this work ? It’s attractive as I can see that the lower part of the soundboard is free to move like a drum , but I am having trouble understanding how the 2 to 3 mm of soundboard takes the weight and doesn’t ballon up . I am a beginner but keen to learn so please excuse my ignorance .
Cheers
Peter Lynch

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kiwigeo
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Re: Beginners question

Post by kiwigeo » Sat Jul 24, 2021 7:09 pm

My understanding is that braces notched into the linings are less likely to come loose. The pay off is a soundboard that is more restrained from vibrating freely at its periphery.

Me....I notch my back braces and top transverse braces but all other braces stop about an inch from the linings
Martin

johnparchem
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Re: Beginners question

Post by johnparchem » Sun Jul 25, 2021 5:07 am

Peter Lynch wrote:
Sat Jul 24, 2021 5:15 pm
... and some seem to end the lower arms of their crossbraces about 10mm from the Kerfing .
In this case it seems to me that tension carried by the strings is being held by the glued rim of the soundboard . How does this work ? It’s attractive as I can see that the lower part of the soundboard is free to move like a drum , but I am having trouble understanding how the 2 to 3 mm of soundboard takes the weight and doesn’t ballon up . I am a beginner but keen to learn so please excuse my ignorance .
The structural braces arc when under tension, so the load is distributed along the brace. Along the brace itself the top is glued to the brace so both the top and brace are taking the load. There is not really very much load at the bottom end of the brace. Also the rims also make very stiff braces, so the top is pretty well supported there. Any of the option you mentioned are fine and can make good guitars.

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TallDad71
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Re: Beginners question

Post by TallDad71 » Sun Jul 25, 2021 7:10 am

I like to notch in my Xbrace and upper transverse brace into my kerfing.

The main benefit for me is that it makes lining up the plates a doddle when I have to glue the sides to the top.

Some well respected luthiers believe that this is essential if the braces are to act efficiently on the soundboard, others are less convinced and believe that as long as the braces are stopping the board from distorting under load it’s all good.

To me It’s such a multi-factoral system you’ve built that it is truly difficult to pinpoint the effect of any one design choice.
Alan

Peter Lynch
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Re: Beginners question

Post by Peter Lynch » Sun Jul 25, 2021 10:32 am

Thank you for the reply’s , I appreciate all information shared .
Thank again 🙏
Peter Lynch

seeaxe
Blackwood
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Re: Beginners question

Post by seeaxe » Sun Jul 25, 2021 11:10 am

TallDad71 wrote:
Sun Jul 25, 2021 7:10 am
I like to notch in my Xbrace and upper transverse brace into my kerfing.

The main benefit for me is that it makes lining up the plates a doddle when I have to glue the sides to the top.

Some well respected luthiers believe that this is essential if the braces are to act efficiently on the soundboard, others are less convinced and believe that as long as the braces are stopping the board from distorting under load it’s all good.

To me It’s such a multi-factoral system you’ve built that it is truly difficult to pinpoint the effect of any one design choice.
I'm with Tall Dad on a steel string, I notch the tops of the linings and leave a couple of mm of the main braces to drop into the notch. A bit of time and care when you are doing this in the dry means that its practically impossible to get the top incorrectly glued up when you are doing the final assembly. Only the main braces mind, the little ones can all stop short.

If you are following a set of plans, suggest you do consistently what the plans say to do, especially if its a first or one of the first guitars you are building. Time enough for experiments later. Whenever I have followed a plan, the results were pretty good. (Cumpiano, Grellier etc)

Good luck with your build.
Richard

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kiwigeo
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Re: Beginners question

Post by kiwigeo » Mon Jul 26, 2021 5:41 pm

For lining up the top/bottom with the sides where braces aren't locked into the linings....glue tantalones on outside rim of top/back against the sides....I do this even when I have transverse braces recessed into the linings. The tantalones get trimmed off when the top/back gets trimmed back with the router/trimmer
Martin

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