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Years ago when Sylvan Wells and John Mays described the Bourgeois double tenon neck joint I started using it based on their tutorials which involved a full mortise on the top for the fretboard tenon and a separate mortise block on the underside of the top butted against the headblock.

I experienced moderate movement at initial string up, more than a glued extension, or full dovetail but compensated with a slightly higher neck angle. What was disconcerting was that at 6-12 months there had been more movement sometimes necessitating a slight tweak in the neck angle. After that they remained stable.

I tried reducing the size of the mortise so more top was glued to the headblock with some help but later found that Dana had gone to a integral one piece headblock, mortise extension and left a slight gap between the end of the extension and the top brace. As he glued his tops first he would then wedge in a piece of wood in the gap to make a tight fit of the headblock assembly against the top brace to prevent rotation.

Over the last few years I have done that but as I glue the back first I access the gap through the mortise for the fretboard tenon. Wedge in some Mahogany tightly and hit it with thin CA to anchor.

I have watched a few of these guitars that are local the last few years and this appears to have solved the problem. They still move a little more initially than a glued extension or dovetail but the long term settling does not seem to be happening. An initial neck set with a straightedge 1/16” over the bridge on an unfretted board seems adequate to deal with the initial movement.

If any of you are experiencing similar problems with the Bourgeois style joint this seem to work. The other option is switching designs like the joint Trevor describes which I considered.

The pictures show the gap with a light in the guitar and the filler strip.

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

Hi Terence,

I'm curious as to why you don't make the neck block extension longer and glue that directly to the upper transverse brace.

Steve

It is difficult to get top positioned perfectly and still be in solid contact with the brace when gluing the top to the rims. The two are frequently not perfectly parallel. It is easier for me to leave a gap and wedge two pieces of wood in very tightly afterwards. Then I know there is good solid contact and maybe even a little back pressure. The beauty of using thin CA is that you can really wedge the pieces in tightly first.

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

Glad to hear it wasn't just me having that trouble. You don't have to off but a smidge to swing the center line a 1/4" at the tail. I've taken to treating the UTB as part of the rim set. Makes it easy to cut accurate notches in the linings and gives a nice solid joint at the neck extension. Since I close the box on the gobar deck, it's simple to add a few more sticks to complete the clamping of the top to that brace.


I am in full agreement with you that this type of neck block should be tied in to the top bracing to fully stabilize the neck. Thanks for bringing it up.


Steve

That's what I was doing for a while. I would leave the UTB square until the ends and butt it right against the sides. I would bend a second false side about 2" either side of the UTB, cut a precise notch in it and slide it over the brace, capturing the end. For my neck block extension, I would leave it long when making the frame, then clamp the frame to the tablesaw fence and bring the blade up, through the block where I wanted it to end, and would glue the UTB right to it.

Ultimately I found there were no recognizable improvements for the considerable amount of extra work so I stopped doing it.

Did that approach help solve the late settling issue Steve?

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

I’m currently installing the UTB as part of the rim assembly which has been working really well for me. I *am* installing my top first but I think it would also be possible to accurately install the top last. I use the mortise to help index the top during glue up (I can do this because my neck block is cut before assembleing the rims). Once the top is dry-fit I use a small block and a baby c-clamp clamped to the top it self to index the top side to side and front to back. All that’s left is to line up the tail block end.

Right or wrong this is how I’m doing it. I will also likely look further into Trevor’s approach.

The image is shown without the popsicle stick brace installed. I let it run through the fretboard extension pocket then trim with a router (1/4” bottom bearing) once the top is glued on.

Michael, I like the way you've locked everything together in the UTB/neck block area. I did a bolt-on fret board extension but decided it just wasn't that hard to remove the glued on extension compared to the extra work involved. I do like to connect the neck block and UTB but it's a bit fussy to get it tight when you put the UTB on the top first. I will shamelessly steal your idea of putting the UTB in the rims with the neck block and try it on the OM I'm doing next.

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Steve Smith
"Music is what feelings sound like"

I know it looks like a lot of extra work but it’s actually really quick. The neck block fits every guitar I make. I only need to cut the extension to length and profile the block for the body radius and cutaway. I make a dozen at a time on the cnc so it’s a matter of reaching for one as needed. I’m down to about 28hrs to build a basic guitar not including finish and any fancy inlays.

I use an acrylic template to make sure the geometry is correct before glueing up the UTB.

Standardizing the neck block and CNC'g them makes good sense. Every guitar I have made is different; I should probably settle on a neck joint design and move forward, it would no doubt save me a lot of time.

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Steve Smith
"Music is what feelings sound like"

I use exactly the same block for my “0” as my 27” baritone. Speeds things up a bunch no doubt!

What a dandy idea! So simple, so easy, so rational, and the brace stabilizes the rim and neck block a whole lot. I will guess that each of us knows somebody whose guitar's neck angle wandered around a fair bit during the top installation as a result of the rim edges moving in or out from the ideal and the movement causing the neck block angle to change.

Thanks!

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Peter Havriluk

Yup...

Yes, really nice set up Michael. Inspired for my next build.

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Thank You and Best To All

I just popped down into the shop to measure a couple shop demo guitars, one being 6 years old, the other about 3 years old. Neither has budged at all from the original setup numbers. I personally think there’s great benefit to tying the neck block into the UTB. The way you come at it is up to you.

Interesting discussion!

Best, M

I agree, great discussion! For those of you that make the top brace/head block construct part of the rimset do you glue everything up and then radius sand the rimset?

If you angle and flatten the upper bout for proper neck/upper bout alignment I assume you do that after the construct is all glued up as well?

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

The neck blocks are made completely square (except for the profile radius and the cutaway if present). That way I can clamp the block to the edge of the bench and glue on the pre-jointed rims which allows everything to stay complainer. Once the neck and tail block are glued in, I place them in the form and head to my radius dish and radius top rims and blocks. Then I glue in the linings, back to the dish sander. Then fit and glue in the UTB, back to the dish sander. Finally I install the popsicle stick brace and back to the sander. In the end you get your 1.5° +/- angle.

How I do it anyway,

M

In a strange way I instinctively tied the last couple of UTB's in to the neck block. Most likely a lot wrong with the details, and no measurements but it made sense intuitively to do so. I will now do the same but with lot more detail to process and intention.

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Thank You and Best To All

Really appreciate your insights Michael. Thank you for sharing them...

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Thank You and Best To All

Yes it did, I haven't had to re-address a setup since.

I think it's interesting that a number of us came up with similar solutions independent of any prior discussion on the subject. Like LarryH said, it just made sense.