Official Luthiers Forum!

Hi all.

Just wandering if you guys could help me find an example of a OM 12 fret bracing pattern.

I'm essentially interested in the position of the soundhole, compared the its position on a 14 fret OM.

Thanks!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Hi Alian,

OMs dont typically come in 12 fret designs .. OM originally meant 14 fret neck, on any and all Martin models, including dreads when the 14fret necks first appeared.

What you probably want to look for is a 12 fret 000, and make it whichever scale length you wnat, 24.9 or 25.4. The guitar might also have either 19 or 20 frets on the neck, putting the centre of the soundhole somewhere around 6.5 to 6 3/4 inches from the neck body joint.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

You might be thinking about the Norman Blake 000 from Martin, which is a 14-fret OM-style body (with appropriate bracing changes) with a 12-fret neck.

I wouldn't worry about the exact position of the soundhole; there's no "right" place for it. When I lay out a plan for a top, the soundhole location is the last thing I figure out, after all the bracing and bridge location.

Draw out your bracing plan and see where the soundhole falls. You can look at the Unofficial Martin Guitar Forum - umgf.com, and their tech forum has bracing layouts that members have contributed. The Norman Blake might be listed there. You might get some bracing guidelines.

Also have a look at the Martin web site and find the Norman Blake model to get an idea. Note how many frets it has (it miight be 19) and see where the soundhole is.

If you need an exact place for it, email John Hall. He'd probably be happy to help you out.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Hi Alain,
I locate the soundhole based on where the end of the fingerboard extension is. Then I draw the bracing based on the bridge. Here's a pic of the guitar I'm building now, which is a 12 fret OOO (OM ?) with a 24.5" scale:


http://www.pattonblades.com/4111-16.jpg

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Regards,
Phillip Patton

http://www.pattonblades.com

The bitterness of poor quality lingers long after the sweetness of low price has faded.

https://hoosierbladesmith.wordpress.com

Thanks a lot for all the quick responses guys!

Pat,
the Norman Blake is exactly what I had in mind. I just couldn't remeber the name. I'll be searchaing for that. Thanks!

I wanted to see an example because even though I'll be moving the bridge down a little more than 1'' (compared to a 14 fretter), I'm afraid that moving the soundhole the same distance is going to look weird.

Thanks again!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

You're right, Todd, I do know better!

Thanks for the mesurements. I'll be able to lay that out on paper before I start cutting any wood.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Check out this thread, meybe you'll find something that interest you.

viewtopic.php?f=10101&t=31617&hilit=fret+neck+body

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Francis Richer, Montréal
Les Guitares F&M Guitars

Just curious?? Is there any specific x brace angle range to try for when moving bridges and soundhole location? I am working on one now that is 93degrees and I think the OM is 98???

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MK5acoustics.com

I think x angle is the wrong discussion. My belief is that with the larger instrument the x needs to come out the long side of the bridge while the smaller instrument needs to have the x come out the short side of the bridge. Instruments inbetween of course would be averaged.
So the process would be to lay out the scale and place the x so it comes out the required place under the bridge. Or just copy what was done already but that doesnt give you any control of the end result. Nor does it give yo any understanding of what is happening.

I dont know if Todd is referring to my post above but the scale you choose determines where the bridge is, it is not up to the builder to select after the scale has been selected. What you can do is move the x up and down or even sidewise. You can open or close the x or not have one. But re the use of the x plan, my thought is that most guitars and expecially smaller ones sound better with the x coming out under the short dimension of the bridge. This can be done by moving the bridge or opening the x angle or both. I also think that becuse larger guitars tend to be boomy, having the x legs come out under the long dimension helps them. So my perspective that the angle or distance from the 14th or other fret are secondary and really unimportant. Just blindly choosing an angle and a position for the bridge fails to understand what is happening with the bridge and its effect on the sound of the guitar. Of course a builder can just copy what a factory does but do you trust that a factory does what is best for the guitar or what is best for the production/profit.