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Neck block w/Support Tongue extension In response to requests, here is a write-up of the neck block with tongue extension that supports the guitar top under the fingerboard extension. The components of the end block, and their relationship to each other prior to being glued into a unit.
The assembled block glued in place.
The “tongue” is constructed from .5” thick mahogany, in this example, and is 2.75” wide. It is trimmed to length to suit the application and should stop just short of the transverse top brace. The purpose of the tongue is to 1) support the fingerboard extension of the soundboard, 2) provide a base wider than the fingerboard extension so that potential cracks in the top, adjacent to the fingerboard extension and running with the grain, are eliminated, 3) eliminate the need for the “Popsicle” flat brace previously used in the preceding item and 4) to free up the upper bouts of the soundboard to contribute to the sound/tone production of the instrument. This last item may be up for discussion, but I feel there is tone (probably in the higher registers) to be had by freeing up this area of the soundboard. In my particular application, the tongue forms a 90-degree interface with the end block. This allows my fingerboard to run onto the top in a dead flat plane. It works for me since my top ”arch” begins about midway in my sound hole and proceeds down into, and through, the lower bout of my top. That has the added benefit, again in my build approach, of having the bridge rotating into a slight “uphill” slope on the top when under string tension. Therefore, before I ever experience a top “caving in” between the bridge and sound hole, the top has to be rotated into and through a flat plane before any dip can occur. It’s just a bit more pre-design to hopefully eliminate a potential problem later in the instruments life.
Photos 6.jpg and 7.jpg show an LMI single action truss rod and it’s relationship to the neck joint.
As you can see, I use the “Cumpiano” mortise and tenon neck joint. Photos 4.jpg and 5.jpg show the completed body with all the cuts required to accept the finished neck.
Not shown is the .250 “ hole drilled in the center of the transverse brace. This hole aligns with the curved slot in the tongue and allows the hex adjusting wrench to slide right into the tension nut on the end of the truss rod…as seen in 8.jpg photo.
I hope this is of benefit to the other builders. Any question may be directed to me at whmauel@inreach.com.
Hank Mauel |
