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...too cool.

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David White, Toronto

"All my favourite singers can't sing."

I'm just skimming, so excuse me if I repeat something already mentioned. I believe that Greg Smallman uses an adjustable neck on his classicals. The adjustment is via a set screw through the fingerboard. Maybe someone could post a drawing of that method.

If you're using an adjustable neck and a full fretboard extension, couldn't you eliminate the UTB? I notice that a lot of builders retain this brace. Even those that have the flying buttress set up.

I've been told that you can as long as you put some bracing there to counteract the forces still put on the top. That's why I'm going to try putting a A type braces from the neck block to the edge near where the upper X brace is or mirroring the buttress. This was suggested to me as a possible option. I want to see if it will open up the upper bout and if it will add anything to the tone. Seems like to me that if the UB can move more then it should have some effect.

Since the fretboard extension is floating seems like the A brace should work. Of course I'm just guessing but I think I would just mirror the appropriate portion of the X brace.

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Steve Smith
"Music is what feelings sound like"

Prehaps an upper bout fan brace.

Perhaps an upper bout inverted fan brace since they would converge away from the soundhole.

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Steve Smith
"Music is what feelings sound like"

Here's what I've found works for me. No UTB, usual soundhole reinforcements, add two small braces parallel to the carbon fiber butress rods. Note, the braces on this top are still in the process of being carved and sanded, so they're a bit rough still at the moment.



Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Dave that's what I had in mind. Have you noticed any change in the tone or volume etc.?

Sure have. There's more of everything - it's much louder, the bass sounds fuller, there's better note separation, and the sound just kind of sparkles more (difficult to find words to describe). The upper bout is free to add more to the sound in this design. In a guitar with the fretboard extension glued/bolted to the top of the soundboard, you absolutely need the UTB (to stop the soundboard from caving in under the string tension) which pretty much cuts off/stifles all but a few treble frequencies from being produced by the upper bout soundboard area. Well, that's my take on it anyway. One day, I'll build two guitars with identical wood (from the same logs) but make one using a traditional mortise/tenon joint and the other with my "bolt-in" neck. Then I'll be able to do the best possible A to B comparison. Don't hold you breath though, I won't have time for this for about a year!

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Hold on Dave, I'm intrigued by your upper bracing and what you say sounds good, but, tell me about the box joint edging of that soundboard. Am I seeing things?

Joe

David Schramm uses this joint on his lattice classicals, too. You might find some info on his website. He has also done a tutorial on it for MIMF. You might find that, too.

Basically, there is a mortise and tenon laying horizontally across the neck body joint along the top edge. This provides lateral stability and location. The strings pull the fingerboard toward the tail such that the head wants to swing up and over in an arc. There is an allen bolt that goes through the fingerboard and sits on bracing that is built into the upper bout under the fingerboard. This is pushing back against the string tension, the mortise and tenon keeps the neck from slipping up and over. The whole thing recesses slightly into the body for a traditional look.

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

Hi Joe,

No, you're not seeing things. This was an experiment that I did a while back. I thought I'd try to laser-cut box joints on the edges of the top and back, and matching joints on the top and bottom edges of the sides. I spent a LOT of time working with the math/numbers to make them all fit together properly (with the sides curved so that they fit properly after they were bent), and it kind of worked. The idea was that I might be able to get rid of the kerfed lining (and reduce weight) and produce a guitar with a unique look. The problem I found with it, and have yet to solve, is that the sides need to be registered perfectly (to within a few thousandths of an inch!) - I could not do this with my Fox style bending machine as-is. I have some ideas for how I might design a new bending machine that CAN guarantee perfect registration and shape, but I have to find more time to work on it. Meanwhile, I decided not to waste the top and back that I did the box joints on. I'm using them in my latest prototype guitar (with my "bolt-in" neck idea). The box joint edge will be routed off when I put the bindings and slightly-wider-than-normal purfling on the guitar, and no one (except you and me) will ever be any the wiser! If I solve the problems with the box jointed sides idea, I'll let y'all know, you can bet on it.

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Have you thought about just laying the top on the bent sides and hand scribing the the joints and cutting them by hand. So I guess you wont have any binding to protect the edges then? Also don't you believe the lining also adds strength to the rim and also helps to keeps the upper bout from deforming from neck torque forces? What would be the advantage of less weight of the linings as opposed to the strengthening of the rim? Isn't the advantage to solid linings and Fox's reverse kerfing lining the stiff strength of the rim?

Hi Chris,

Yes, I thought about doing it that way, however it's a LOT of work, and those little castle edges are fairly fragile and easy to break off (especially on the EIRW sides) - the chances are I'd break a few trying to cut them by hand. The next idea I'm going to try is cutting the sides from 3 or 4 veneers (laser-cut, of course) and then glue them up on a former with matching box joints cut in it (actually, in reality, probably a simple plywood form with acrylic sheets attached to each side, with the box joints cut into the acrylic) so that everything registers beautifully. Lack of time to do these experiments is my big problem right now.

As for the strength of the box and/or the sound differences, yes, sure, this will probably make a big difference. Structurally, I was planning on strengthening the box in other ways (CF is my buddy). Actually, I wasn't so much interested in the weight reduction as I was in how cool a guitar built this way would look. If it weighed a few ounces less than "normal" guitars, then that'd be cool too (just for bragging rights). Sure, the edge would be a bit more vulnerable to damage, and you'd never be able to remove the top or back again for repair, but so what? It'd be one cool looking instrument while it lasted, and who knows, it might even sound good. If it got damaged too much, I could always cut another one on the laser fast enough!

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

You can cut it with a router or table saw just like a drawer box joint. If you are afraid of breaking the cut from sawing by hand then I don't see that joint being very strong and not breaking and splitting along the grain unless you back it some kind of lining whether it be wood or CF. Have you ever seen Howard Klepper's Zipper or Dovetail guitar where he uses dovetail joints all over the guitar?
How and why do you think it will make a big differance sound wise?

The box joint edges are weak only until they are glued together. Once joined, there is a huge glued surface area, and the fact that the edge becomes continuous will ensure enough strength. If it needed small blocks or some CF, or even some kerfed lining to make it strong enough, then fine, I'll add some. Like I said, I'm not married to the weight loss thing. Actually, if I were to go to all the trouble of hand-cutting the joints, I'd laser-cut "doves" on the edge of the back and top, then hand-cut matching "tails" on the edges of the sides to make true dovetail joints - that'd be even cooler! Why would this make a difference sound-wise? Well, if the box joints alone are enough structurally, then I'll be increasing the size of the soundboard by about 3/8" all the way around (because there wouldn't be any linings). That, surely, will make a difference? Why not just wait and see? Surely it's worth an experiment rather than trying to shoot it down before I've even tried it?

If I'm not mistaken, Howard's dovetailed guitar is actually fairly traditionally built. I believe the joints are cosmetic and are for show rather than structure. However, I'm not at all sure about this - perhaps if Howard is tuned in, he'd care to inform us?

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I think I have my doves and tails backwards....never mind, you get the drift.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I'm not shooting it down. I'm just asking questions. If you said you were doing it because you thought it looked cool then I'd would agree. I'm just asking questions and making suggestions as how it might be done and if it would be stronger and why you think it would effect the tone. Part of those joints are going to be end grain to end grain so I don't know if that added surface area is going to be strong and I don't really see there being more surface area being glued but less since you are gluing the edge of thickness of the sides and top together as opposed to the surface area of the lining. Isn't that less gluing surface? Correct me if I'm wrong, I don't have a problem with that. That's how I learn from asking questions and having things explained as to where my logic is wrong.

For my adjustable necks I use Greg Smallman's style neck joint. It is pretty self explanitory. The retaining bolt holds the neck on when the string are removed. The neck is adjusted through a hole between the 17th and 18th fret. Action is adjusted under string tension.

I've built this style guitar with and without the adjustable neck. There is no difference in tone.

What material is the black ledge that the neck fits against?

Good Morning David,
Welcome to the forum!

Thanks for posting those pictures. That is the style of joint that has been running through my head for the past couple of weeks. I just couldn't remember where I saw it. Simple and to the point, no side to side adjustment, no difficult to source hardware. A real K.I.S.S. construction method.

Steve

Hi David and welcome to the forum

My first adjustable is a Doolin type and I appreciate the simplicity of your neck joint. I like the fact that the pivot point is right up by the fretboard. I also have some questions:

I see you have the top cutaway where the fretboard extension overhangs the rosette area. It appears that your fretboard would recess into this opening, is that correct? Also, do you have any reinforcement on the top at the area where the rosette is cut out?

I am also curious, What is the black material that the pivot ledge is made from? Is it the same as the material the setscrew bears against?

Do you mortise the neck block for the neck after the box is done, or do you finish up the neck block ahead of time and maintain alignment of the centerline as you build?

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Steve Smith
"Music is what feelings sound like"

The fingerboard matches up with the soundhole and rosette. The top is very thin, 1.2mm with a 0.020” crossgrain mahogany veneer in the upper bout and rosette area. The pivot bar is made of carbon fiber. The setscrew plate is steel.

The plywood chassis is made prior to attaching the top, back, or sides. The double mortise is done when I make the chassis. After the body is complete I fit the neck and heel one at a time then I glue them together. The heel is reinforced with a 3/8” CF rod.

In this photo I haven't installed the strike plate for the setscrew or the retaining screw hole. Those are done when I install the neck. Neck instalation and fit is done after the body is complete and ready for finishing.


This photo is during the voicing stage. I no longer voice it like this, but who knows I might do it again someday.



This is what it sounds like with the back off.

KISS construction??? Looks like more work to me and doesn't free up the upper bout or have a yawl adjustment. But maybe that's just me.