After a short break, work is continuing on the Walnut bass. The next task is to fit the truss rod, this is normally a job for the router, however after recently buying a plough plane, I thought I'd have a go at cutting the channel by hand.
With the neck clamped to my bench, I start by drilling a hole where the truss rod channel will end.
The adjustment nut is slightly larger than the rod, it also needs to room to turn freely, so I use a slightly larger diameter drill bit and mark out the section of wood to be removed later.
Time to starting planing the channel.. I use the hole at the end of the channel to line up the cutter and then lock the fence in place. I also apply some candle wax to the plane (and the fence) to help stop it binding.
When using a plough plane, you start towards the end of the cut (so the headstock end in this case) and gradually work backwards, taking longer shavings and establishing the channel with each pass, until you're taking a full length cut.
The plough plane is intended for cutting a groove all the way along a board, from one end to the other. Cutting a 'stopped groove' like this one causes an issue, as the design of the plane makes it impossible to cut at full depth at the stopped end of the groove. So to remove the remaining wood, I use my little Veritas router plane. I also square off the end of the channel with a chisel.
With the main channel cut, I use both the router plane and a chisel to cut out the area for the adjustment nut, followed by a small rasp to blend it into the headstock.
The channel has been cut about 2mm deeper than the rod, this allows me to glue in a fillet of wood which helps to stop any rattling if there's no tension on the rod, as well sealing it off from glue when attaching the fretboard. After applying a little grease to the threads of the rod, I spread a thin layer of glue to the sides of the Maple fillet and then clamp it in place.
Before capping off the wider part of the channel with a small piece of Ebony, I apply some decorators caulk around the adjustment nut, as this can also rattle if the truss rod isn't under tension. Although it stops the rattle, the caulk stays flexible and doesn't affect the adjustment of the rod at all.
Once the glue has dried, I plane the fillet flush. The neck is now ready to be cut to shape and for the fingerboard to be attached.. more updates coming later this week.