I don't claim to have invented this design, but here's how I make a robust neck through with a heel, leaving plenty of space under the lid for pickups/bracing etc. There are plenty of ways to go about this, and no right or wrong way. However this design helped me overcome a number of obstacles in my early builds. I will skip over quite a few basic aspects of CBG building so it might be an idea to have a grasp of scale lengths etc. first.
This article is not aimed at seasoned builders, but rather those who were just starting out. Or even more specifically, myself about 3 years ago when I started making these!
The only thing this diagram doesn't show is 'back angle', which I use on all of my builds to improve ergonomics. Just imagine the block at the front on the box is lower than the one at the back. It's that simple, and can make a big difference to how well a guitar plays. This, along with some other tips is covered in another how-to here.
So - you need a 1 metre length of hardwood, and a separate fretboard (6.5mm/1/4"). Cut the neck blank into 2 pieces. This will depend on the kind of box you are using. You want the upper piece to extend into the box by about 100mm, and the lower piece to extend roughly 40-50mm from the front of the box, creating an overlap of roughly 6"/150mm (see the picture above). You can use whatever headstock design you prefer, scarf etc.
The first job I do is cut and glue up the scarf joint. I cut the scarf using a jig and a big chop saw. Along with the Dremel and drill, these are the only power tools I use to make necks.
To glue up the scarf, I clamp the two pieces of the neck to the bench and then apply a clamp at the joint. If it slips, move the pieces back and try again. You want to get this right. Some people swear by sprinkling a little salt on the glue to stop it slipping. I haven't tried it myself. Once the glue has fully cured I slice off some material from the top side to bring the thickness of the headstock down to about 15mm.
While this is drying, time to take a look at the fretboard:
So at this point I've marked the frets using a metre ruler and Stew Mac's Fret Calculator, scored them with a knife and they're ready to slot. It is worth investing in a purpose made fret slotting saw and mitre box for this job. I've drawn a centre line and marked across the frets diagonally to place the marker dots. Carefully drill them out to the required depth. This would be much easier with a pillar drill but I don't have one.
Once the fret slots are cut, I taper the fretboard. This step is completely optional, but since trying it I have found it impossible to go back to square necks. If you want some tips on doing this, I wrote a 'how to' here. Once you're happy with the shape of the fretboard, you can add your side dots, if you wish.
In the below picture, I am gluing all of the remaining parts of the neck together; the fretboard, the lower portion of the neck that runs through the box, and the headstock 'wings' which will allow me to get a bit more creative with the design. These are made from fretboard scraps.
I leave the neck in the clamps for 24 hours. I know many people would say this is unnecessary but I prefer to err on the side of caution. This is what it looks like after taking the clamps off. In this picture I have already used my mitre box to create a 'slope' where the two neck sections meet which will be the basis of the heel.
...and after tapering. Again, this is an optional step, and there is a 'how to' here.
So here's the neck so far. Time to get shaping - in part 2!