This is the jig I set up to cut about 3/8" off of the front of the neck. This will make the neck thin enough to accept a maple
top of the same thickness as the amount that I cut off. This is important because without this step, the fretboard will be too
low in relation to the top surface of the bass (which creates a tangle of problems down the line with pickups, bridge....).
I cut and stacked 3/4" plywood so that it was high enough over the fingerboard on both sides of the neck. Next, a piece of bubinga
was jointed on a jointer so that its lines were very straight, and each surface was an unperturbed plane. The bubinga was lined up
carefully to exactly coincide with the very edge of the ebony fingerboard. This is my router guide. The template router bit I use
has a cutter, and a ball-bearing that is the same diameter as the cutter farther up the bit shaft. The ball-bearing follows a template
above the piece to be cut and creates a cut that has the same lines as the template.
The left picture shows how the jig was secured with shims of wood that held the neck at exactly the right height so that it didn't pull up,
nor was pushed up. If this happened, the jig would cut an angled plane into the neck, and not a plane perpendicular to the back of the
neck. Shims were placed between the clamp and the fingerboard to prevent marring. The second picture shows the result of the template-guided
router cut at its final depth. The template can now be removed, and routing can be finished by guiding the router on the plywood over the neck,
being very careful to not cut the fingerboard.
As I work down the neck, the plywood has to be moved as well. You can see a pencil line on the side of the neck. Any maple
below the line will be removed with the jointer.
The picture on the right shows just how thin the neck is now. It is ready for the bubinga backing to be glued.
The bubinga backing overhangs the edges of the neck quite a bit. The picture on the right shows how much bubinga was trimmed off to match the
Bubinga makes lovely shavings, and is great to work with. The picture on the right shows the thickness of the bubinga after gluing and trimming.
It will be thinned on the jointer to the final neck thickness.
Here is the final thickness of the bubinga backing, quite thin. The body wings were placed beside the neck, and a steel cabinet scraper
was used to level the router cuts (plywood isn't perfectly squared).
After much scraping and checking for gaps with a straight-edge, low-spots were marked and more scraping ensued ensuring a perfectly level surface.
This kind of accuracy is very important for instrument building. The correct positioning of other components (like the bridge) is dependent upon a
true surface. Small inaccuracies are compounded at each step of the building process (the effects of which are more dramatic the more laminations and
pieces of wood used), and if not checked, will result in a poor-playing and likely
poor-sounding musical instrument.