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Hello everybody,
My first build is running into a problem.

Some infos first:
- 24.4 dread in the works
- neck and unfretted fretboard are straight (checked with a straight edge)
- the top has a 25" radius
- the upper transverse brace and the popsicle braces have no radius
- prior to installing the top, the upper bout of the face of the rim was flattened
- I just set the neck angle: When I place the unfretted fretboard on the neck, place the bridge in its correct position and place a straight edge on the unfretted fretboard, the straight edge is almost 1/16" over the bridge.

Now here is the problem: Coming from the neck/body-joint, there is a gap opening up between the top and the straight fretboard. The further it comes to the soundhole, the bigger the gap is (at the rosette aprox. 1/16").
When the neck and body are finished, I need to glue down the fretboard to the top. With this gap, the fretboard will not be straight anymore (starting at fret 14). I am confused if this is a problem or not and how to handle it ?!?

Any help is highly appreciated. How should I proceed?

Not to worry you are fine - your neck simply needs to be fitted/flossed. This is part of every build.

Here is how I do it: http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=15022%22

Also - I can't remember if the toot address the concept of fall-away for the fret board extension but I like to build in .010 - .020 of fall-away into my guitars. After reading how you did not radius the upper transverse brace and flattened the upper bout (I do this too) I am going to guess that you will have about .015 of fall-away which is great IMHO. Let us know how it comes out?

I don't do my neck joints like this anymore, BUT, when I did I had a jig that replicated the proper height/angle of the fretboard to bridge and I used this to sand the proper angle into the top of the guitar at the fretboard extension landing area(where you are having issues). A little dropoff past the 14th fret is not necessarily a bad thing, but a 1/16" might be a bit much(maybe .015 would be OK). You might be able to fix the angle without too much trouble....I guess you could also build a wedge to go under the fretboard extension but that would be my last resort. Sorry I don't have a picture of the jig, but it could be as simple as a piece of wood(proper height-same plane as where the fretboard should land above the bridge) at the bridge location with a sanding bar coming off of this piece toward the neck block, lightly sand until you have a proper angle landing zone for the fretboard extension.....hope that makes sense. Without seeing your situation in person I can't be sure that this is going to work perfectly, especially considering the gap you currently have, be careful and go slow. Considering that your top is flat, the sanding is most likely going to take away some thickness at the binding area around the neck block area and if you need much you are going to need to spread this out across the that top area or you will wind up with a divot/trench in the extension area.

Cheers,

_________________
Gwaltney Guitars

Hey Hesh,

I am delighted to hear from you and hope you are doing fine.

Well, your post got me confused, because I actually followed your great toot
viewtopic.php?f=10102&t=15022&start=0&st=0&sk=t&sd=a
to set the neck angle. Following this I got the straight edge almost 1/16" over the bridge.

I also had one of your toots called "Truing Upper Bout" on my harddrive (but didn't do true up the upper bout). In there you wrote "A much simpler method is to bolt on the neck, place the fretboard on the neck, place the bridge where it will go, and place a straight edge on the unfretted fret board pressing it down to kill any bow. You want the straight edge to be just over the bridge 1/16" or so."

So the question is: Do I want the straight edge (again, placed on the unfretted fretboard) to almost touch the top of the bridge? Or what is the desired height I am aiming for?

Regarding fall-away: None of your toots talk about that and I only found one thread talking a bit about that. Could someone go into a little bit more detail please?

I appreciate your help a lot. Thank you all.

Hey there Christoph

There was an excellent thread on the OLF in the past about neck angles and in that thread (I am not finding it right now...) various builders talk about the neck angles that work best for them. Remember too that not everyone uses the same size bridges and saddles either so that can complicate things.

These days I like the straight edge to come in just skimming the top of the bridge with the neck in place, fret board clamped but not glued, and no frets installed yet. If you check out Stew-Mac's free-for-download dread kit instructions they are looking for the straight edge to just kiss the top of the bridge too. But there is some leeway here provided that we all understand the ramifications of an over and under set neck. For example a saddle that is too high can stress the bridge and result in a split in time in the front of the bridge. If your saddle is a thicker saddle (some builders can use up to 1/4"...) and/or if your saddle is slanted backwards intentionally (or unintentionally... ) stress on the front of the bridge can be reduced.

Another thing to consider is that your bridge will at some point be flossed too to fit the dome of your top. When you floss/fit your bridge material will be removed probably in the center area of the bridge and then the bridge will sit lower than it does right now. Depending on how much flossing that you need to do to get the bridge to sit flat that 1/16" that you see now may increase by the reduction of the height of the bridge resulting from flossing. It's all related....

If it were me I would continue to floss the neck until the neck angle is reduced and the straight edge is kissing the top of the bridge. If you do this without flossing the bridge you will be safe because I don't expect that flossing will reduce the height of the bridge very much. But with the 1/16" that you have now any additional gap is approaching being problematic in my mind.

Fall-away is the idea that the fret board extension distances itself at a greater rate from the strings from the body joint to the sound hole. This is done because the strings are lashing around when played to the greatest degree near the center of their "speaking length." More distance between the strings and frets where the strings lash the furthest means that the guitar will potentially buzz less when beat on (played hard).

Lots of builders build in fall-away and if you need one name to validate the concept try Mario - he does it and he also looks for about .015 fall away.

I just reread the toot and I seemed to like a gap of 1/32" above the bridge back when I did the toot... 1/32 is fine IMHO but I would reduce 1/16" of a gap under these exact circumstances, unflossed bridge, unfretted neck, etc.

Hey Hesh,

Thanks a lot for your great answer.

You are right: The unflossed bridge is 350/1000 high and will def. come down a bit when sanded.

I am back to smiling because I understood and know what to do right now. You even made me understand fall-away, which makes perfect sense to me aswell. But this raises one more question: How do you build in fall-away?

Regarding this here gap.

Well just read the above posts and you be fine. Especially Hesh's tutorial.

However here is a story for you.

One day me looking at that gap of over 1/4 inch and was just about to quit building in frustration when me eyes glanced over to the violin me lady friend had just brought into the shop. Talk about a gap...only they call that gap a cantilevered finger board. Hmmmm.... So me look a some pics of arched tops and yup, big gap that they stick wedges under. Bigger Hmmmm....some bells and whistle and me brain went south for a holiday.

So me thinks.... me got 4 choices here....

a) Do whatever it takes to close the gap. (the net didn't exist then, info was hard come by)
b) Slip in the wedge
c) Quit luthierie
d) redesign the instrument as a cross between an arch top and a violin neck joint.

Well I did a) of course.

But on the next build opted for d) In time me ended up designing a whole new instrument out of the deal. Best holiday me ever had.

Me hear what you saying about "the gap" but please Christoph, don't see it as a problem...its just as another situation that needs to be dealt with. And me sure you will do just that just fine.


Blessings
the
Padma

_________________
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Audiences and dispensations on Thursdays ~ by appointment only.


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Great to hear and thanks for the thanks Christoph!

OK the way that I learned to build in fall-away was simply by doing what I do as an individual builder and seeing what happens. So when I did very much the same things as you do I noticed that I had some fall away. I adjusted my technique until I consistently had .015 of fall-away.

To summarize how I get the fall-away that I do take a look below but also understand that all of these things are being done in context and are part of a building "system" that I do, for now. All builders have their own system and this is just a glimpse of mine. Also before I forget what I have learned is built upon the sharing of lots of folks here on the OLF in the past - thanks very much to them!!!

1) No radius on the upper transverse brace

2) 25' dome on the top

3) Assumption that a 1.5 degree neck angle will be "flossably close"

4) After the rim is radiused in a 25' dish (top) I elevate the tail block 1/8" with the rim face down on a flat surface with self stick sandpaper on it. Prior to doing this I make pencil marks on the kerfed linings and neck block on the top side from the neck bock back to the waist area. I then with the top face down move the top back and forth pivoting it on the elevated 1/8" tail block and flatten the upper bout of the top until the pencil marks are gone up to the waist. (there used to be a toot on this process)

These things done in concert provide me with about .015 of fall-away.

Again there are lots of ways to do this but this method works for me for now.

I hope this helps.

Thanks Padma!!!!

Hey everybody,

The "problem" turned out to be no problem and is solved: The neck joint got some more sanding action. Now the straight edge sits a litte bit below 1/32" above the bridge blank and the gap between the fingerboard extension and the top (at the rosette) is in the range of 1/64" (hard to measure).

I call it the end of a stressful day with my first neck setting experience. Thanks again for all the help. You rock.

Case closed.