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12 fret dreadnaught question(s)
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Author:  Bob Carpenter [ Mon Apr 20, 2009 6:08 pm ]
Post subject:  12 fret dreadnaught question(s)
Hi gang, I'm new to the forum and I've been lurking a while (nefarious reasons... ;) ). I've poked around looking for an answer to a question I have but haven't found it. What are the contruction differences between a 14 fret dread and a 12 fret dread (other than the distance to the body). I guess I'm wondering how the extra two frets affect bridge placement, body dimensions...

Thanks! Bob
Author:  bluescreek [ Mon Apr 20, 2009 6:24 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
It is good you are thinking but remember the bridge placement is the same in that it is all related to scale length. Once you know the scale length you can place a bridge. The only difference between a 14 fret and 12 fret is the body length. The distance from the nut to the saddle will be the same as long as the scale length is the same.
The bracing is the same , just the body is lengthened .
Author:  Flori F. [ Mon Apr 20, 2009 6:29 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
This is just the beginning of an answer and I'm sure others will along with more informed comments. That said, building a 12 fret guitar (not just a dread), pushes the bridge down the body. (stew mac has a fret calculator that you can use to help locate the new bridge position.) Moving the bridge shifts the bridge patch down as well and suggests a re-location of the x-braces. (You probably want your x-braces to overlap the back corners of your bridge.) From there, you can locate your finger braces and tone bars wherever you like. It might help to start with a plan and modify.

I just saw John's post...You can do as John suggested. I just prefer to redesign the bracing.

Hope that helps.

Flori
Author:  Darryl Young [ Mon Apr 20, 2009 8:44 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
Wow, two completely different approaches to teh same question.

John's approach lengthens the upper bout so the neck meets body at the 12th fret.....meaning nothing changes except the shape of the upper bout of the guitar.

Flori's approach is what popped into my mind when I read the question, shorten the neck by the length between the 12th and 14th frets........which will move the bridge lower, more in the center of the lower bout. This would probably change the angle of teh X brace and you might shift the finger and tone braces as well (ala, the differences between a standard OM and the Norman Blake).
Author:  paul h [ Mon Apr 20, 2009 8:55 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
On my 12fret dreds I split the difference-I lengthen the body enough to make up for one fret, and move the bridge down to make up the rest of the difference. You do have to shift the bracing, but that is easily done.

Paul
Author:  Bob Carpenter [ Mon Apr 20, 2009 11:11 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
Cool, thanks for all the replies. It appears there is more than one way to fry this fish! I'm guessing there is no one "right way". I have heard people say they like playing a 12 fret guitar because of the tonal differences from a 14 fret. I'm guessing that bridge placement would potentially have the most affect on tone.

Cheers! Bob
Author:  Hank Mauel [ Mon Apr 20, 2009 11:59 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
You can think of a 000-12 fret guitar, such as a Martin, and then "blow it up" to the dreadnaught size all around. The major effect of the 12 fret instrument is to place the bridge farther down on the top in nearly the center of the lower bout. This has been referred to as the "sweet spot" and helps define the tone/volume of any 12 fret instrument in a variety of body sizes.

A couple of photos below show a 000-12 fret and a 12 fret "D" style. You can see the relationship of size as the body enlarges and the proportions also.
Author:  bluescreek [ Tue Apr 21, 2009 7:12 am ]
Post subject:  Re: 12 fret dreadnaught question(s)
It matters not if you are building a 12 fret or a 14 fret. Martin , does change the body while other builders change a neck. To build any guitar you need to know the fret scale length . All bracing is scale length oriented. Once you know that , you will know where the bracing is plotted. If you are building a Martin style 12 fret , the bracing doesn't move in relationship to the nut . The bridge doesn't change location, the body changes shape. There is a difference.
That is all you have to do. Martin uses the same bracing on a 12 fret as the 14 fret. The truss rod brace and Popsicle will move as per 12 or 14 fret. With the Norm Blake `12 fret , the bracing will move down the body as martin placed a 12 fret neck on a 14 fret body but it is still oriented to the scale length. IF you are designing your own guitar plot your bridge location first and set your bracing to that. There are a number of designs.T can tell you , the CF Martin design uses the same bracing pattern for all scale lengths it is just moved to match scale length. That was the original intent of the X brace. When you get into the smaller guitars below the 0 , they take out a tone bar and a finger brace.
The original X brace design uses a 93 degree angle.
John Hall
Blues Creek Guitars
Authorized CF Martin Repair Center
Author:  Bob Carpenter [ Tue Apr 21, 2009 9:30 am ]
Post subject:  Re: 12 fret dreadnaught question(s)
Great information, thanks so much! Bob
Author:  Flori F. [ Tue Apr 21, 2009 9:49 am ]
Post subject:  Re: 12 fret dreadnaught question(s)
I forgot to mention...I move the soundhole too. I like to keep the soundhole close to the heel block, so I've been building 12 fretters with 19 frets and place the upper soundhole edge just below the 19th fret.

Hank, can you comment/offer your thoughts on soundhole placement in a 12 fretter? It looks like you built that 000 with 21 frets and the dread with 19. The soundhole starts just below in the last fret in both.
Author:  Bob Carpenter [ Tue Apr 21, 2009 10:19 am ]
Post subject:  Re: 12 fret dreadnaught question(s)
So if I'm thinking in terms of how Martin builds 12 fretters, the bridge/bracing position is fixed and everything else (upper bouts, neck length...) changes in relation to scale length (say 24.625).

Bob

Image
Author:  Hank Mauel [ Tue Apr 21, 2009 1:19 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
Flori F. wrote:
I forgot to mention...I move the soundhole too. I like to keep the soundhole close to the heel block, so I've been building 12 fretters with 19 frets and place the upper soundhole edge just below the 19th fret.

Hank, can you comment/offer your thoughts on soundhole placement in a 12 fretter? It looks like you built that 000 with 21 frets and the dread with 19. The soundhole starts just below in the last fret in both.



Generally I end up with 20 frets. On these particular instruments, the 000 had a 24.9 scale and the dred had a 25.7 scale. That extra .8 of an inch cost me a couple frets on the dred. Also there was a bit of soundhole location change in relative terms between the two. The 000 was moved down just a skosh which also helped get the "extra" fret. All things being equal, you would "normally" see 20 frets on either instrument but I do adjust on custom builds to get the sound the customer wants.
Author:  Flori F. [ Tue Apr 21, 2009 6:01 pm ]
Post subject:  Re: 12 fret dreadnaught question(s)
Thanks Hank. [:Y:]
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