What is this thing? Stewmac OM plans.

[ColestineGuitar]

Hey, that's great! Thanks for the picture, Ken. I don't see what possible support the cantilever can provide, given that the fretboard, with a much larger surface area, is glued to the top in the exact same area.

[kencierp]

Agreed! --- I tell guys and gals to cut it off.

[deadedith]

I noticed this in Somogyi's book - he makes quite a point of supporting the extension and reinforcing the soundhole with this type of block.

[kencierp]

To each his own -- if you don't control humidity, the area from the bridge to the neck block will cave in no matter what you glue in there. I don't agree that the neck is forcing the entire upper bout section of the top forward (how can that be?) nor do I agree that the finger-board extension is being compresses against the top and pushing it down- ward. I would agree that there may be a slight increase in the mass of the neck assembly which is said to reduce the tuning fork effect and unwanted energy transfer from the sound board which gets lost through the end of the head stock. $.02

[deadedith]

Maybe after I've squeezed every last bit of sound and tone out of my existing procedures, I will worry about the tiny bit escaping through the neck area. Until then, and that may take one or two more guitars :-) I guess I won't trouble my pretty head about Somogyi's procedure. Thank goodness.

[kencierp]

John Hall can chime in but I had heard Martin added this piece of material to help control lengthwise cracks along the fingerboard edges.

Build a guitar with a butt joint neck and free floating FB extension. I did just that and still have it in my shop -- for me it dispels some common guitar making conventional wisdom.

[JRHall]

Martin actually uses it as a clamping caul for the fret board extension. Really handy during assembly, but no use afterwards.

[tippie53]

You can see that upper part is glued on , To make it out of a single piece would be pretty wasteful . I can assure you , the blocks have been glued up since the started this design . The original block omitted that piece. I am not sure of the date when they started using that .
It can sometimes appear to be a single piece but look close and you can see the glue line at that point . Jim is correct it is just a production time saver .

[Ben-Had]

Looks like a Flux Capacitor to me. Only Doc Brown or Marty McFly can help you with that.

Be careful, it takes 1.21 gigawatts to attach or remove one!