Sunday, February 17, 2013
How do you get the neck off? It's a question I've been asked quite a number of times. When a steel-string guitar has an excessively high action and a very low saddle it's usually time to think about re-setting the neck. People often assume that the neck of the instrument has bowed forward under string tension. It's true, there is a tremendous amount of force working on the guitar, trying to bend it. Often though, there's a more localized distortion that happens where the heel block area has tipped forward as can be seen (greatly exaggerated) in the drawing above. Students at Timeless Instruments build with an integral heel block and Spanish foot, and the geometry works quite well at spreading the forces over a larger area by coupling to the transverse brace in the upper bout. Even if one decides to use a separate neck and block, it might be a design upgrade to incorporate the foot into his or her neck block.
I'll remove a narrow wedge of material along the edge of the heel where it makes contact with the body, effectively tipping the neck backwards by about a degree.
A straightedge laid across the frets meets this dreadnaught bridge about halfway between its surface and the face of the guitar, and the action at the twelfth fret is uncomfortably high, almost 1/8" (3.1mm). It's best if the straightedge contacts the top of the bridge, leaving some room for action adjustment in the height of the saddle. This is a Canadian instrument built in the early 80's by Claude Boucher and Robert Godin. It was an inexpensive but well-crafted guitar aimed at serious students.
Some yellow glue (not epoxy!) and careful clamping, and it all went back together again.There's almost always some fretwork necessary beyond replacing the one I removed, as the fingerboard extension will settle into some slightly different geometry and odd buzzes will occur. The action at the 12th fret is now more friendly, and the neck is sitting flush with the body again.