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I have the OLF OM plans (14 fret at the body) and want to build a 12 fret OM. I have one question and want to make sure one of my assumptions is right. Question: does the sound hole get moved at all or should it stay where it is shown on the plans? Assumption: I assume I should locate the bridge based on the scale length and then shift the top bracing accordingly so that the bridge plate and the X brace are where they should be in relation to the bridge. Is this correct? Also, any other changes that I should be thinking about or aware of? Thanks.

Hi Stephen,

Pretty much all you need to do is lengthen the upper bout, and of course make the neck shorter. You will want to modify the bracing in that are also.
The lower bout and X-brace can remain, as well as the bridge and bridge plate locations.

Also, technically, if you make it a 12-fret instrument it is no longer an Orchestra Model. It goes back to being a OOO.Don Williams38968.5688425926

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

OK, now I need to be taught something.

Why lengthen the upper bout? To make up for losing two frets? And is that why the bracing, etc. can stay the same in the lower bout? And is this true if I go with a 24.9 scale length?

That whole OM/000 distinction always confused me.

Thanks.

On my 12 fret 000 I do move the sound hole and make it a little larger but I don't change the body shape at all. This is what Martin does on the Norman Blake 000. I move the Soundhole back enough to allow for 19 frets and shift the bracing back to adjust for the scale length. On my 12 fret models I use the 24.9 scale instead of the 25.4". On my 14 fret OM I have a 3.72" sound hole but on my 12 fret it is closer to 4". I really like the sound this gives and it makes it simpler for building, I can use the same forms and moulds as the 14 fret model. The traditional way of course is what Don suggests above and if you want to do that you can always buy a set of 12 fret 000 plans.

Sorry for my ignorance but I assume what Don is describing is using a 25.4 scale?

[QUOTE=SStallings]That whole OM/000 distinction always confused me.[/QUOTE]
No OM's have 12-fret necks. No OM's have the short scale. If it's got either one of those, it's a OOO. Simple.

Stephen, what Martin Guitars did to create the OM was to shrink the upper bout of the OOO, and use a 14 fret neck with the longer scale. Obviously the bracing at the upper bout had to change. Not sure though if they moved or changed the soundhole at all. I forget now...

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Stephen,

I think your best bet would be to buy a set of OOO 12-fret plans, and mix-and-match with the OLF OM plans as you see fit.

To make a OOO from a OM body move the sound hole to the 19th fret of a 24.9 scale 12 fret at joint fretboard. ModifY the X-bracing to to fit 24.9 scale. make the sound hole between 3 7/8" dia. and 4 1/8" dia. 4 works good for me. This gives a OOO using all the components and fixtures for a OM.

I'm with Michael, and we are in good company as that is what Norman Blake did for his signiture Model. It is realy easy to do. Just take the plans and shift soundhole and bracing down and it fits perfect. I have a template I use for Bracing and if I line up the soundhole on the template from the OM (25.4" scale) with the new sound hole position the bracing is perfectly placed for the 12 fret 000