More necking
Today I took a built up neck billet and cut the parts apart using the bandsaw. When the billet is cut, it looks something like this, with it’s two necks and center section that will eventually be cut apart and become the outside edges or “ears” of the peghead.
The accuracy required for this next cut is unforgivingly high and one that takes a bit of set-up time. It’s the cut that establishes the neck angle as well as the length of the fretboard. It’s called a scarf cut and it runs at the same degree angle as the peghead to fretboard angle. This shows the jig I’ve built to help do this important cut safely and quickly. In this shot, I have a piece of scrap mounted in the jig that’s been cut to the same dimensions as the neck shaft just to make sure everything is cutting square and to the correct dimensions. Far better to test this critical set up using scrap rather than the actual neck that’s already had numerous hours of work put into it’s construction.
Once the scarf cut is complete, I’m left with these various parts.
The next step in this little dance involves attaching the offcut peghead to the neck. It’s hard to see beneath all the clamps but the offcut piece has been flipped around and is being glued on to the back of the neck shaft. The clamps on the left hold the neck shaft to my table saw bed. The clamps on the far right serve to block the movement of the peghead as it’s being attached. They’re necessary because the slanting cut of the scarf joint produces a wedging action when the center clamps are tightened and if they weren’t there, when pressure was applied to the center clamps, the headstock would move out of position. And of course, there are the four clamps in the center that actually clamp the headstock to the neck shaft.
In my previous post, I mentioned that it was critical that the thin ebony center seam be cut so that it had an unvarying width or there would be problems down the line. It’s at this point in the build that any inexactitude would show up. When I flip the headstock, I have to line up the black center seam of the neck shaft with the seam in the headstock. Since this pairs the front side of one surface with the back of another, any discrepancy in the width’s of the center seam would be glaringly obvious at this joint. Also, the two halves of maple on either side of the center seam have to have exact matching widths or the center seams of the two parts wouldn’t line up correctly. In the picture that follows, the center seam join is just to the left of the closest glue block. While you can see the line produced from the angle of the peg head, the center seam is of equal width and lines up with the center line of the neck. Taking the time to build that scarf cut jig has paid off again. Good thing, since that jig took a ton of time to build!
Once out of the clamps I’m left with this, or rather, these; the neck shaft with attached peghead and the two “ears.” The ears will nicely hide the angled scarf joint from the sides of the peghead, and the ebony headplate that will end up being glued onto the front of the peghead will cover all the joints from that side. On the back, only the joints where the ears are attached will show and those are actually in keeping with period construction and, as I’ll go into in my next post, effectively hidden because of wood choice and positioning. Finally, the scarf joint is effectively hidden because it occurs right where the break angle between the headstock and neck shaft is formed.
The major reason I build instrument necks in this way, beyond the fact that it uses wood more conservatively is that it imparts much more strength or break resistance to the neck-to-peghead area of the neck. Built the traditional way, there’s not a lot of long wood fibers present to provide strength to that area. Using a scarf joint approach puts lots of long fibers in that area. The weakness of a neck built in the traditional manner was best illustrated to me when I visited the shop of another local luthier who had what he referred to as his “Wall of Shame,” where upon he’d attached all the broken off pegheads he’d gathered over the years from neck repair jobs brought to him. There must have been thirty or forty pegheads in his little display. Truly impressive, almost pretty in a way, and truly scary. Next up, giving the head “ears.”
