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I have the neck on a 14 fret OM and have some neck angle issues. I have set the neck angle such that with a straight edge running down the fretboard, the top of the straight edge just kisses the top of the bridge. Now I have a gap from fret 15 on down. At fret 20 the gap is approx. 020". If I decrease the angle of the neck, the fretboard will straighten out but I will hit the top of the bridge. Am I down to a wedge under the fretboard where it meets the guitar body or is there a different fix? I'm sure that some string pull will straighten out the neck some but how much should I allow for that given the bridge height issue? Any insight is appreciated - first guitar and all.

Randolph, sounds like you have the neck set dialed in pretty well. I'm wouldn't change your neck angle or you will end up with a really high action. I typically build with the top of the rims sloping from neck edge of the soundhole to the neck joint. This allows the f/b to sit lower at the 14th fret and thus keep the f/b level from fret 1 to the last fret. At this point, though, you don't have many options. You can do as you suggested and put a ramp or wedge under the f/b. If you are planning on binding your f/b, you could install your wedge and make sure you have the plane you are looking for, then bind the f/b and cover up the wedge. Your binding will be a bit taller under f/b extension, but that would probably look better than having an exposed wedge. You could also glue your f/b extension down or if it is a bolt on neck, devise a means to bolt the f/b extension down. A number of builders and players actually like a slight slope down after the 14th fret to provide a bit more clearance in those upper registers while having a low action.

Ken

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Yes, the top is sloped from the soundhole to the neck edge. The fingerboard is bound already which is why a wedge makes me a little nervous. I hadn't thought about bellying at the bridge. The top is fairly lightly built - .106" - .110" When I flex the neck holding the body stationary it does relieve the fall away mostly. Would it make sense level the fingerboard under simulated string tension?

let me ask a couple question. Did you radius the UT brace? Did you radius the UT brace less the area of the fretboard extention or dod you make a true flat UT brace? Not that it matters at this point. Also does your neck block have a cantileverd flange for the fretboard extention? If so was the flange sanded to the dome profile. Which brings up an other question did you sand the dome profile into the rim prior to attaching the top? if so it is easy to have the sanding dish tilted a tad bit towards the tail instead of level wich can lead to this issue (assuming that the tapered gap is larger at the end of the fretboarrd than at the 15th)



these days I use a flanged neck block and the flange is at a 1.5 degree angle to match the plane of the set neck. I do not sand any profile into my top rim. I use a UT brace that is radused except in the center wher the fret board extention will cross. when I fit the neck i keep the fretboard extention flat to the top and pay attention to how the heel is setting aginst the rim. that tells me how I need to adjust the heel. With this flanged neck block I have far less flossing required and no gap problems.

Now to handel your current issue. .02" is a fair amount of gap. In my opinion the wedge fill is the best fix. use the same material as the Fb binding and it will be less noticable as a fix.

Thank you Ken, Todd and Michael for your responses. They is very helpful not only in getting through this situation but in visualizing for the next build coming up.
Michael, my UTB is dead flat, I did use a cantilevered flange on the neck block and there is a dome sanded into the rim as well as the neck block extension. I do believe at this point that the source of the problem was a bit of tilting on the sanding dish toward the tail. This explains clearly why there is the amount of fall away past 15. It seems to me that if I knew how much change there was under string tension, then I could determine how much of a wedge to use or whether to shine it on. Do you have a method to simulate string tension at this point?

I never have used simulated neck bending to replicate sting tension. I have in the past use the truss rod to impose bow based on the deflection that the string imparted but this did not work all that well for me because it does not affect the extension proportionally. In my years of building I have found that the best results I have gotten have been from mounting the neck including gluing the extension in place then leveling. Of course this in tales protecting the body finish during FB leveling, fretting, fret leveling and dressing. However this is more work than the conventional method of doing all this prior to attaching the neck but it allows you to correct things prior to fretting. I still use this method however I have switched to a bolt down FB extension. I do not sand the rim to the dome profile because I do not want to end up sanding the flange on my neck block out of plane with the neck. I want it to stay parallel to the neck/fretboard plane since I taper all my bracing to Zero at the lining the top has no problem conforming to flat rim and linings. In fact I do not taper the top of my rim at all I allow the neck block flange to impart the proper slant into the top at the extension. With proper bracing and dome radius this very little that the top is being deflected beyond the shape formed by the bracing. but I want the area under the extension to be dead parallel to the neck plane. this system works well for me.

Thanks Michael. I haven't heard you're method of not doming the rim before. It is definately great food for thought. I can see the issues it resolves. My fretboard extension is a bolt down so I could theoretically do my final leveling (before fretting) and after finish with the bridge on - viola! string tension - hadn't even thought of that! Thanks again for the help.

Like Todd and others said .020 should be OK as a lot will disappear with string tension. The first thing the old timers that work at the store where I sell my stuff do when evaluating a guitar is look down the neck for a rising fretboard extension. That's the kiss of death. They like a little drop off after 15. I usually sand in about .010 when leveling and sometimes that's barely enough when strung up if it's lightly built. You should be fine.
TJK

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It's not what you don't know that hurts you, it's what you do know that's wrong.

that's a very interesting topic.
I've got a question for those who don't do sand any profile into my top rim : how much radius do you put on the UT brace ?
thanks

I leave my UTB completely flat.This seems to work fine.
James

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James W Bolan
Nashville Tennessee