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This may be a dumb questions but hey, I'm far from a pro. . .

I know that it can be good to mill in fallaway since neck relief is seen between the nut and heel but not so much over the body. This can result in the fret plane actually rising from the middle frets (where relief is the most pronounced) towards the end of the board. I'm into 12 fretters these days and I'm not 100% sure where to start the fallaway. If the neck joins at the 12th fret, that means that the heel shape is supporting the neck around 9 or 10 so there is not much deflection. It seems un-natural to start the fallaway before the 12th fret though. Someone straighten me out please.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I built a copy of a Martin 12 fret single "0" a while back and just did the fall away at the neck joint like a 14 fret and it seemed to work. I'm thinking about my next project and would like to build a 12 fret slope shoulder dreadnaught. Do you just shift the bracing pattern South to fit ? I have drawings for a J-45 Gibson I would use and modify for the neck join.

Imo fallaway should start at the body join. Be it 12, 13, or 14.

There was a pretty good post back a page or two that discussed this.
But if you keep the same scale length, yup, move the bridge back and adjust the bracing to suit.
I’ve got a 12 fret dread on my project list too, so I’ve been doing some research myself.

IMHO fall away on acoustic instruments isn't necessary and I know that I share that opinion with some highly regarded luthiers even though Hesh gets mad at me when I say it

In my instruments I see relief extend over the body joint to the last fret. It took me a while to figure that out but I finally got it and it's a beautiful thing to behold. So if you only see relief from the nut to the body join then I think something else wrong is going on there. And if you just sanded that hump out you would have the proper relief.

For a long electric guitar I get the concept of, shall we say, second relief. But I don't see that on acoustic guitars especially 12 fretters.

The other argument for relief is something I've been wanting to investigate more and that is to correct the inevitable distortion of the neck block area that happens over time.

Start the fall-away at the 12th regardless of where the body join is.

Fall-away is even more important with a 12 string because very low action is not only usually desirable it's more important on a 12 string since they are harder to play anyway.

Fall-away's importance has nothing to do with the guitar being an acoustic, electric, 6,7 or 12 string. It has to do with the physics of a string and the vibrating wave. Where fall-away becomes more important is when lower action is desirable.

Additionally the guitars that we and others build change in time. Be it low RH exposure or string tension or top movement the fret plane will move after the instrument is built and as it settles in. Fall-away also is insurance that if things such as ski ramps start to develop they are pretty much countered in advance and may not be an issue.

the fall away doesn't need to be much. .020 may be all you need.
I so mine using RH. I will level frets at 60%rh
that will give you a nice fall of that is fitting for the movement of that guitar.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Mario who is who introduced both Dave Collins and I to the very concept of fall-away is keen to do .010 to .015" of fall-away measured at the last fret. So as John says it does not take much to do the trick and keep those over the body frets from preventing low action or two step bends from choking out.

We do that .010 to .015" too and I did it on the slightly over four dozen guitars that I built and sold.

Had one more thought at work today that I wanted to add for Bryan.

Yet another reason why fall-away is especially desirable with a 12 is the strings on a 12 tend to be lighter gauges than 12's. The lighter the strings the less inertia they have to overcome so they tend to lash out further and if there is a fret in their path they will find it.

Hesh, I’m asking about 12 fret neck joins not 12 strings. Either way, it sounds like you are starting fallaway at the 12th for 12 fretters and 14 fretters. That is what I did on the two 12 fret guitars I did and that is what I will do on the ones I’m working on now.

Thanks to everyone for the input and discussion. I don’t say it often enough, this place is great!

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Whoops yep I go confused trying to answer questions on a few forums at once and mixed up the issues. I get a lot of questions on Facebook and PMs here and elsewhere. There was a 12 string in the mix yesterday.

YES we start fall-away at around the 12th regardless of if it's a 12 fret, 13 or 14 fret (or 12 string.... ). There is no magical, mystical super precise measurement to how it starts at the 12th it's just the beginning of a very gradual dropping off of the fret board from that point to the sound hole. For those considering fall away the sound hole area is where we dig in when playing. It's where some of the biggest hits a string takes are done. That's also one of the reasons why we want the clearance of fall-away on the very first frets that a vibrating wave of a string sees along it's path to the nut.

You are very welcome. Good luck with your 14 string, 9 fret