It is a lot easier to cut the angle for the front of the headstock before the
fingerboard is in place, but most of the other shaping of the neck is done
once it has been attached, so that the neck is made as a whole unit. Here you
can see the angle that the headstock will be made at, and the truss rod
access channel (despite the dazzle of the flash). Note that the neck blank is
considerably wider than the fingerboard. The excess width will be needed for
the headstock, in particular.
Also, this may be one of the few pictures of Jack Read you
ever see - that's his hand there!
Here we see the neck with the fingerboard attached. Hidden beneath it is the
installed truss rod, but you may just be able to make out the access channel
where the fingerboard meets the angled cut for the headstock. It is clearer
in the picture below. At the other end of its extent, in the middle of the
neck, the truss rod is held in place by the force of its own compression;
it is a simple little system, really, but it allows a significant amount of
adjustment to be made.