Official Luthiers Forum!

I have a question for the forum. I've built electric guitars before, but now I want to take on my first acoustic. I like LMI and their serviced kits, they could save me a lot of grief for my first time. But I want a crossover guitar. I was thinking I could use the basic OM kit, carve a wider SS neck, and use classical tuners and bridge.
But here's my dilemma; I think I'd get better tone and sustain if I decreased the bracing in the box.
Are there any plans for a lighter braced OM?
Could I copy fan bracing into the OM body?
Or am I worrying about a very small technical difference?

All comments will be appreciated.
Thanks.

Hi Crow and welcome to the OLF!

I think that a typical OM braced guitar would need more to drive the top than you would get from nylon strings. As for bracing it differently there are no plans that I know of for a crossover pattern. So you would be in new territory not that this is a bad thing but your results would not be ensured by a time tested design that many have built prior.

Have you considered a slightly different approach and that might be to start with a LMI classical guitar kit and make a narrower neck? At least the bracing pattern would not be the issue but you would not have the OM's scale length.

Again welcome to the OLF!

You may want to contact George Leach at Phoenix Guitar Co. http://www.phoenixguitarco.com/

He's been building nylon string OM's for about 10 years or so. He's a great guy and a teacher as well.

Building a good nylon string guitar is a Quest endeavour. There's more to it than just changing the fixtures.

I would suggest finding plans for either a classical or a flamenco guitar that you like, and then overlay it onto your OM outline. Classicals tend to be more in the size range of an 00.

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You need to look at this from the mechanical perspective. Yes the OM body “SHAPE” can be built into a viable classical nylon string guitar. Fender does just this thing. But the bracing, plate thickness, bridge design, neck design and sound hole location all are vastly different than an OM steel string guitar for mechanical reasons. Nylon strings exerts less tension and far less energy so the working of the body and neck must be designed for far different requirements.

Why try and reinvent the wheel? If you want to narrow the neck that would be doable. I'd get a good classical kit and use that as the base.

Colin

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The real crux of this post is that "Crowland85284" wants to convert a LMI OM serviced kit to a classical. It is doable but will need to purchase a classical neck and fretboard or build them, purchase a classical bridge or build one, and thickness the plates as required by a classical design.

Just seems to me he is looking for a serviced classical kit. Guess what? LMI sells them to!!! Make much more sense to me

While the OM shape is not an issue the other components of the LMI OM kit will not work well.

I agree with Colin here (surprise surprise) If you take a turkey and want to make it quack like a duck you are likely to end up with a goose

What a great idea Michael and Colin - wish I had thought of it.....

Oh yea you did!!!! yep I saw, just reiterating your wisdom

he did not say but maybe suspect he already has the OM kit in hand

Some perspective:
The 12-fret 000 was the last guitar Martin designed for gut strings, around 1909, iirc. As time went on, and steel strings became more popular, they beefed up the top a bit. When the jazz banjo players wanted a guitar with more frets and a flat headstock to record with, Martin cut down the upper bout of the 000 at the 14th fret, and used banjo tuners, to make the first OM.

I've made two classical guitars on the 12-fret 000 pattern, and they have worked well. Sharon Isbin tried one out last winter, and liked it, so what the heck. Aside from the wider fingerboard, you do have to lighten up on the top and bracing. That calls for some judgement, which is well informed by experience, but it's not impossible to do the first time out. You can, BTW, use the pin bridge, although I'd try to get a 'pyramid' bridge rather than the later 'belly' style. That's what Martin used on their gut strung guitars. The belly bridge is heavier than it should be for nylon strings, and you don't need the extra glue area in any case.

Can you get LMI to swap out the bridge, neck, and fingerboard?

I am with Al as I have done this also. I did this based of Stew Mac plan for 12 fret (it is basically their kit plans) I think. Since I like the pyrimid bridge used one I had. I used the nylon Folk guitar strings. Sounded and played fine, but I am not going to claim it was a pure classical sound as it had some difference in the voice, but not that much to my ear. Guess that is why I called it a folk guitar, but that was my own name for it as I didn't know what else I can't describe it but very nice and still going. I went 1/4 bracing all the way on guitar(maybe even little smaller but not much if at all) went with a thinner maple bridge plate, top was about .090 or so. I wouldn't do anything with it but nylon strings though or might have a headplate to butt wedge head knocker. I also did a dovetail neck to body join.