Simplified neck construction and strength.

[JimCh]

I'm locked down away from my workshop and most of my tools. I'm mulling over building a semi-hollow mandolin, but I've never tried building a neck, and the limited kit and even more limited experience is a concern.
I have an idea of how I can simplify things a bit for the tools I have, but don't know if it's got obvious flaws. It occurred to me that it would be much easier to build the neck if I could just plane flat rather than any concaves. It seems to me that if I shape a piece of wood so it's tapered with four flat faces that would be straightforward with available tools. Then I could glue on a headstock from a rather wider piece of wood with a conventional splice joint. Does that sound feasible? What are loads like, could I get away without a volute at the splice?
The other thing is strength. I really don't want to source a truss rod and install, but I do have a stock of unidirectional carbon fibre and experience using it on boats. I could laminate uni carbon into a slot in the back of the neck, and even run that right across the splice onto the headstock. Carbon there ought to be a lot more effective in resisting bend than the conventional thing of putting carbon rods in the middle of the neck. It does seem as if some mandolins get away without a truss rod, am I likely to have a vaguely usable instrument with minimal neck relief?
My current instrument is a roughly 100 year old Washburn bowl back which is charming but unsophisticated, so the bar is not very high...

[Marty Jacobson]

The classic way of making a neck or cylinder is to start with a block. Plane the faces in half, now you have an octagon (or neck with four sides). Then plane those faces in half, now you have an 8-sided neck. Which looks pretty cool, and you could leave it at that. Or you could do a little light sanding and go from there.

You really don't need much to make a neck... the joinery and flat surfaces are the hard part! The rounded part is easy, just use rasps, spokeshave, or whittle it even. Then sand all around with a cork or felt block until it's smooth.

You can make a trapezoidal neck, it's kind of a thing in metal guitar circles. Look up Rick Toone's guitars.

As for carbon reinforcement, getting it as far away from the center of the neck as possible, whether on the front side or the back side, will make it most effective. Old school statics, Mc/I. https://ask.learncbse.in/t/in-the-be...hat-is-c/27604