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What are you doing with the fret board extension when using an adjustable neck joint. I'm using an Doolin adjustable neck joint on my build and I am looking for ways to treat the tongue. I want to have the tongue float. I have an idea of what I'm after but not sure if it will work so any infomation on what you do or have done and what was or wasn't good about it will all be helpful.

I think most that use adjustable neck and floating extension have CF rod extending near full length either side of centerline from the near the nut to near the end of the fretboard extension. and channel the ne neck block to allow for the CF rod to clear

Thanks Michael, I've seen a couple of those but I'd like to get some details from those people. Like do the rods go all the way through the neck or just from the heel and under the extension? Round tube or solid square rods and why and where to best buy and etc. And even if there are bracing cosideration too. You know, anything that can help and maybe to expand on. I just don't see much infomation out there on this and would like to see it out there for us wanting to use this joint.

I have seen it both ways. If i was going to do it I would want my rods to run through the neck to the end of the extension. I have see both round rods and retangular rods used.

That's why I'm looking for info. I don't know if I want to stiffen my neck maybe just the extension.

I just switched over to a floating fb extension and tried a few prototypes before coming up with this. I wanted the extension to be as thin as possible which made it necessary to have 4 cf bars. 2 was not stiff enough and resulted in lack of volume and sustain as you played up toward the end of the board. My cf bars start at 1/8" x 3/8" and are inlet into the fb about an 1/8". They then taper down to 1/8" x 1/4" at the end. I don't run them full length but stop them over the the heel, about 1.5" in.

Another consideration is reinforcing the heel itself. The higher the frets are above the top (thickness of the fb extension), the more leverage on the heel and the more the heel wants to flex. I run a spline through the heel and mortise it through the neck when I glue on the heel. This is quite strong but I still get more movement than I would like. I may go back to a tenon neck joint rather than a butt to stiffen that up a bit more.

I get my cf here... http://dragonplate.com/ecart/categories.asp?cID=20

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http://www.chassonguitars.com

Hi Chris,

I don't want to discourage you as maybe I was just inept at designing and building the adjustable neck with floating fretboard extension. Now it did work, but not like I thought it would, there are little quirks that go along with this joint, at least with mine. What I found was that as string tension is put on the neck it drives the extension down into the top of the guitar, I know it seems couterintuitive knowing that the neck is solidly secured to the neck block/body and while it doesn't tilt/move the darn extension dives into the top of the guitar, drove me crazy trying to figure that one out. The only way that I found to counter this was to put some sort of blocking device/shim between that part of the neck that is away from the body(up high) or a similar block under the fretboard extension and the rim of the guitar to keep the extension from tilting down. The problem I found was that this solution takes away most of the adjustability(though you don't need much, that's true) so in the end I ditched the idea....maybe someone will enlighten me here and I'll give it a go again.

Cheers,

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Gwaltney Guitars

Don't worry about it Greg. I'm not easily discouraged. That's why I posted the discussion. So others then just me can hopefully get some answers and information .

Los Alamos Composites, a sponsor here, is a supplier of CF. I met Jim Watts of Los Alamos at the GAL convention this summer, and he impressed me as a supremely nice guy. If he doesn't have just what you need, I bet he'd get it for you.

I have some other thoughts on the FB extension, but my little girl needs me right now...

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Greg, Something Kent talked about made me think of a possible cause of your diving extension. That is the flexibility in the heel. When you tension the strings up, it there was any movement of the neck shaft in relation to the heel (in other words if the neck moved up a little with the heel staying stationary), the fingerboard extension would have a tendency to take a dive. Did this guitar have a neck tenon, or a spline in the heel? Was the heel pretty skinny?

It seems to me that floating fingerboards almost demand flying buttresses ala Turner/Keppler/White.

Keppler (prefers the term struts I think)

http://www.klepperguitars.com/about.html

Turner (Pdf at bottom of page)

http://www.renaissanceguitars.com/compassg.html

White

oops Dave is rebuilding his site.

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"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

Yeah Barry, I figured out what was happening as it was the only logical explanation, but it still mystified me as I had all of the "stiff stuff" in there. I did question a few other guys using adjustable neck joints and they explained that their joints/extensions did the same thing. Seemed weird to me that this was typical, maybe a thicker heel would have helped....Ahh, I'm happy with my current setup anyway, I don't think I'd go back to that system even if I was convinced it would work.

Cheers,

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Gwaltney Guitars

Greg, I think we're on the same page here but just to be clear, you're thinking the whole neck is pulling up because of the heel flexing, right? The extension diving is just the symptom.

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http://www.chassonguitars.com

Yes Kent, exactly, even though the heel was firmly secured to the neck block and not moving away from the points of contact.

GG

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Gwaltney Guitars

Kent's FB extension looks good to me. I don't think you can get good volume/sustain/tone from notes fretted up there if all you have is a couple of CF rods under the FB extension. In my current design, my neck shaft extends all the way up under the FB extension, and that neck shaft extension is thicker than what Kent shows here - tapered similarly, but thicker. I'm not trying to make it as thin as possible because I am deliberately going for a raised neck angle in relation to the soundboard. I use two CF rods running most of the length of the neck shaft, continuing into the extension. You can't see them from underneath, like you can in Kent's, because they're buried in the thicker wood of the neck shaft extension. I do not inlet them into the bottom of the FB.

Kent, you don't have the problem Greg is describing, do you? ...Because of the reinforcement of your heel, and, moreover, because of the way you support the neck block inside the box.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

BTW, my whole heel is inlet into a pocket in the neck block. Therefore my heel has a lot of meat to it, though it doesn't look particularly thick from the outside. I use a 3/4" dowel in my heel. This reinforces the heel and gives the threaded inserts side grain to thread into. A 3/4" dowel gives a decent amount of meat on either side of the inserts.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Todd, mine does move a bit when I string it up and continues to creep for a few weeks. I've learned to account for it in the initial setup and I keep these guitars in the shop strung up to tension for a month before shipping, then do final setup. My oldest one of this design is less than a year old though so I don't have enough history to say for sure. But I do take comfort in the fact that a neck reset takes as little as 30 minutes, an hour at most.

My next run of necks will have a larger spline, tapered to get wider as the heel does.

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http://www.chassonguitars.com

Why don't you guys use a tennon?

The way my heel is inlet into a pocket, or mortise, in the neck block, you could say the whole heel is a tenon. It goes in about 3/8" deep on my alto guitar, which is the only instrument I've completed with this joint so far (another alto guitar and an SJ-ish guitar are in the works). If I understand correctly, Kent's joint isn't actually adjustable; it's simply a bolt-on butt joint with a floating FB extension. He said he might go back to using a tenon to make a more rigid heel. In my case, I am considering adding a tenon. The whole heel would still be inlet as well, so that there is no visible gap involved in the adjustable joint (I'm an admirer of Rick Turner's let-it-all-hang-out joint, but I have my reasons for choosing a joint that looks more like a normal neck joint). The main reason I'm considering adding a tenon is so that I could use barrel nuts instead of threaded inserts. This would mean making a substantially larger neck block, though, to accommodate not only the pocket for the heel itself*, but also the mortise for the additional tenon. I'm not sure I want the more massive neck block, but I could probably figure out ways to design it to reduce mass, so I'm thinking about it.

*The pocket for the heel itself doesn't necessarily have to be very deep for your average guitar, but some of my designs, like the alto guitar, involve a tight curve to the body at the neck block, so the pocket does have to be pretty deep to accommodate/conceal the heel and the hardware in there.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/