I've tried several different ways of attaching necks to bodies. I decided to go with a straight dovetail for this project owing to the low-profile design I have in mind for the heel. The original Gibson mandolins had a complicated curved pattern obviously machined on a shaper with custom knives. Though not quite beyond my skill level, the amount of time needed to cut it by hand seemed wasteful.
This is a jig for my router table originally made to cut straight spline joints for classical necks. It works for dovetails too. There is a bearing on the shaft of the bit which rides against the walls of the slot
The neck sits at a five degree angle and so I had to make up a wedge to keep it registered. You can see that I will nibble away at the sides of the heel and gradually move the neck over. As it turned out, removing material made the neck progressively more prone to tipping so I left a generous amount of waste to be refined by hand.
Cleanup was accomplished with a chisel and this handy sanding stick that has the 14 degree angle cut into it. I aim for a very slight taper, so the fit gets tighter as the neck is pressed home into the slot.
Like so. The neck actually stands proud of the block by about 1/2" (12mm). This will accommodate the thickness of the top and an added fingerboard support extension.
I'm experimenting with solid-surface countertop material for a headstock inlay. Mother of pearl and the pretty shells of various bi-valves are now extremely hard to move across borders due to the U.S.A passing a piece of legislation called the Lacey Act. This is such a complicated issue. In short, there are a great many natural materials which are legal to own, but sometimes illegal to sell, modify or move across state lines or into the country. This Corian blank is about .100" thick (2.5mm). I've surrounded it with some hardboard to provide a stable surface for my miniature router and I glued on a slip of paper with some guidelines.
A tiny little carbide burr will be used to cut nearly all the way through the material and then the outlines will be smoothed up by filing. There will be some wiggles and eccentricities because I am not a laser engraving machine! A cavity in the headstock will be routed to fit and black epoxy employed to hold things in place and fill the gaps.
I don't often put my name of the headstock of instruments, but this is small and subtle and will be partly obscured by the strings. As it turns out, the radius I used on the end of the headstock is at the outer limits of what one can bend wood binding to. I had a big pot of boiling water and a little form to pin it to but it fought me every step of the way.