Altering bracing

Stray Feathers
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Altering bracing

Post by Stray Feathers »

Hi - I'm new here, introduced myself in the newbie section. I want to build a guitar and am narrowing the model to a 12-fret spruce/rosewood 000 or OM. I was leaning towards a 000 kit but a friend gave me some wood, lots of tools, and a form for an OM-style guitar. He has moved on to carving amazing birds, but built two or three OMs from the book and plans by Jonathan Kinkead. So I have a leg up to do one of those, but I don't really want another largish 14-fret guitar. I have found 12-frets more comfortable and they suit my playing style better. I also want a 1 13/16 nut at least. I know there are 12-fret OMs e.g. the Martin Norman Blake models. I am still at the design stage, and my question is, can I modify the Kinkead plans to change the bracing for a 12-fret neck, with the bridge moved a little lower on the lower bout? And would it be a nightmare to try to use a shorter scale? I have looked at some excellent links here and elsewhere on bracing but have not found the answer to my question. Just so you know, I presently have a Larrivee D-09 and a Martin mahogany 000-15 slot head, and I have the Cumpiano book as well as the Kinkead. If my idea is not advisable, I may go back to looking at a kit for my first effort. Thanks for reading through this -

Bruce
tippie53
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Re: Altering bracing

Post by tippie53 »

sure you can.
If you just squish the heel up two frets you can get it there.
The OM and 000 14 fret are actually the same shape. The Norm Blake is actually a short scale not OM so officially it is a 12 fret 000. The longer scale may push the bridge too far down.
Keep in mind the braces are scale length oriented. start with the fretboard . Plot the saddle position and then you can plot your bracing from that . As for bracing , is you use the lower part below the sound hole , keeping in mind it is based off scale length and bridge position the upper section is based off the neck block . Keep it simple you will figure it out. Don't be afraid to ask questions.
On a 14 fret body with a 12 fret neck the upper braces won't move much , the lower ones will about 1 1/2 in. Use 18 or 19 frets instead of the 20 and DO NOT USE THE SOUND HOLE TO PLOT BRACES.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Stray Feathers
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Re: Altering bracing

Post by Stray Feathers »

John, thanks for the explanation and encouragement. I like the Blake model configuration, what you describe as an OM body with a 12 fret neck. You suggest that a short scale is better in this design, and I see Taylor makes "Grand Concert" models that are similar. This is what I think I want. So next question. If I start with the fretboard, design it with 18 or 19 frets depending on space, leave the soundhole where it is, and locate the saddle according to scale length, can I assume that the relation of the lower bout bracing to the saddle will be the same? i.e can I shift the X lower without changing much (except of course the lengths to meet the sides properly)? Is it critical where the bracing meets the sides? And if as you say the bracing moves about 1.5 inches with the change from a 14 fret to a 12 fret neck, am I correct in thinking that would be reduced about 1/2 inch with a change from 25.4" to 24.9" scale?

Some of this may be elementary or not critical, but guitars seem like magic to me and I don't want to mess with any proven formulas or ratios or best practices.

Bruce
tippie53
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Re: Altering bracing

Post by tippie53 »

pretty much
by using an 18 fret board the hole will go down some but not so much as to look funny. It is all about the scale length and bracing. On the norm the the braces are spread a bit wider with a wider angle but still catch the bridge lower corner.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Alan Carruth
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Re: Altering bracing

Post by Alan Carruth »

The original Martin 000, from 1909, iirc, had 12 frets to the body. Later they went to the 14-fret OM (Orchestra Model) which has a somewhat (about 2 frets worth!) shorter body. If you really want to make a 12-fret 000 you might want to make the longer box, which is about as long as a Dread. It has a somewhat different sound than a 14-fret, even one with a 12-fret neck.

I'll note here, before it comes up, the the difference in sound between 12-fret and 14-fret instruments is often attributed to the position of the bridge on the lower bout. Many people feel that the bridge 'should' be at the widest part of the bout. That's one of those things that's just true enough to be 'obvious', but not really true. In fact, the 'right' place to put the bridge is determined as much by how you place and profile the braces as any other factor. You can move the bridge quite a way above the wide part of the bout, within reason, and end up with a perfectly fine instrument.

Remember, too, that while in theory there is no difference between theory and practice, in practice there is. While a small difference in bridge position might matter a lot in a 'prefect' instrument, I have yet to see one that's close enough for that to matter.

Oh yes: I've made guitars with the 12-fret body and 14 fret necks, and they work ,too.
Kevin Waldron
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Re: Altering bracing

Post by Kevin Waldron »

Top should look something like this.

Blessings,

Kevin
NNJKER389305.JPG
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ruby@magpage.com
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Re: Altering bracing

Post by ruby@magpage.com »

Bruce
This is your first guitar (impression I got) and who knows if you will build more than one. Just because you were given an OM body mold does not mean you have to build that guitar.

As has been said, the 12 fret 000 with the longer body is fine guitar - and since you already have a 000, maybe a 00 size. Or if the body mold is discarded, ANY guitar you can think up is possible.

Ed Minch
Ed M
Stray Feathers
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Re: Altering bracing

Post by Stray Feathers »

Thanks to all for helpful comments. Kevin, your image of the bracing is useful, though I'm not clear if it is from a 14 fret OM or a 12 fret neck on an OM body. After mulling things over for a long time, and learning as I go, I realize I want a 12 fret instrument because I want a shorter guitar, so the long-body 000 12 frets don't really achieve that (though my Martin 12 fret is a delight to play.) For anyone interested, here is a link to Kinkade Guitars (made by Jonathan Kinkead - note different spelling). The model covered in his book is the Kingsdown, modelled after an OM. In the section called "Handcrafted", there are some images from the book, including one that shows the finished top bracing. For me, building one of these (if I can customize it) is partway between a kit and scratchbuilt, with some savings in setup, and a good specific how-to manual (except it doesn't cover a modified scale and neck.) If I could find a kit for an OM body with a 24.9 inch scale and 12 fret neck I might be tempted . . . And if this one goes okay I will have more confidence about starting completely from scratch.

http://www.kinkadeguitars.co.uk/index.php

And one question - I notice on the Kinkade guitar some of the smaller braces do not extend to the sides. Any thoughts as to why?

Bruce
tippie53
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Re: Altering bracing

Post by tippie53 »

the guitar isn't much smaller as a 12 fret. The body is longer on a Martin style 12 fret. Yes the braces are not all tucked in a guitar. The top transverse brace and the X braces are the only one tucked. All the back braces are.
See the braces all are part of the top system. Some structural some tonal and some anti split. That doesn't say they don't all contribute in some way to tone and structure
The Transverse is a structural brace and needs to be tucked. The Popsicle is anti spit and doesn't need to be tucked.
The X braces are both structural and tonal and need to be tucked. The tone bars are tonal and help with the tops voicing. No tuck
finger braces are more anti split but do tie in the bridge no tuck.

I hope others chimes in , this is a great topic.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Kevin Waldron
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Joined: Sat Sep 11, 2010 1:28 pm

Re: Altering bracing

Post by Kevin Waldron »

Showing two instruments both are at the same point on the tail piece. One is a 12 Fret OOO the other a 14 Fret OOO.

Blessings,

Kevin
MS OOO Comparision.jpg
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