Making the truss rod – obviously!
The truss rod is there to counteract the bending effect of the strings under tension. There are loads of different types of truss rod but I make my own like this. The threaded part of the rod goes through the hole so the nut can tighten down on it. The other hole only goes halfway through and the other end of the rod goes into it. When the nut is tightened it tries to compress one side and stretch the other side of the rod which causes it to bend. This type of rod makes a very smooth even bend and is very strong and responsive.
The slot for the truss rod is made with a router cutter with a round bottom to match the rod. The fillet also has a slot cut into it with the same cutter. When the rod is in place this fits neatly around it making it very strong and …if I may say so….. elegant.
The fillet is glued in place over the rod and spring clips hold it in place while the glue dries. Another advantage of this type of rod is that it can be easily replaced – it just slides out. Of course you would have to take the neck off first…..