Hey guys.
I'm quite new in the world of guitar constructions, but I spend long time modifying my guitar on my own.
What I try to say is I can't really tell you anything directly about the rods you're talking about.
BUT I spend many years with windsurfing, surfing and diving.
In these sports both titanium and carbon fiber are absolutely essential for high quality products.
Titanium is light and extremely strong, stiff and expensive.
Titanium blades stay way longer sharp than steel blades for example.
Carbon fiber is the magic invention after the glass fiber.
Extremely light and stiff. Very good flexibility. High end windsurfing masts are made out of 100% carbon fiber.
They allow the sail to twist, but it flexes really fast into its needed position.
I started to imagine my first guitar project from scratch and thought exactly about what you guys talking about:
Stiffness and reinforcement.
When you look at a classic surfboard, there is running a wooden bar through the whole center line called stringer.
In more complex windsurfing boards these stringers are modified to dense foam coated with carbon fiber and/or keflar fiber.
Also the mast tracks have special fiber reinforcements.
My idea was now to split up the whole neck or even the whole guitar to run a hardwood/laminated wood stringer through it with a layer of carbon fiber on each side.
It would guarantee and enormous strength and stiffness which would lead to a higher sustain and less twisting problems.
Now entering into detail about your questions:
You have a long cavity running along the whole neck, why not trying to coat it from the inside with a layer of carbon fiber?
If you would apply it properly with as less resin as possible and no air beneath you would get an supporting tube running invisibly along the whole neck
and protecting also your sensitive first frets.
I just read the first post again, you already planned to glue the neck out of several parts,
you could even make a combination of one of the mentioned thrust rods, a stringer and an inner carbon coating.
If the stringer also runs all along the headstock it should be nearly unbreakable and extremely stiff and twist resistant.
I hope you guys understood my ideas, like I said in the beginning I don't have your guys specific knowledge but I love creating and combining and transferring techniques.
Sorry for entering in more details again:
I just checked your mentioned thrust rods, I would prefer the carbon version.
If I understand it correctly they are mainly intentioned to run beside a main rod, because you cant adjust them at all.
In the instructions it says that the titanium version needs no resin, which is correct,that would not make any sense at all because it won't stick to the metal surface.
But if you sand the carbon rod and than apply the resin it gets one single piece with the surrounding wood!
It still offers a slight flexibility, is lighter and really, really stiff and strong...
I guess I'll stop now, I guess you got it.
I'm looking forward to discuss about this topic, I would really like to see guitars with up to date technologies and materials.
I don't really understand that the guitar industry sticks so much to designs and methods invented 50/60? years ago.
In it's moment it was really cool, but hey guys, we're in the 21 century.
That doesn't mean at all that I don't like oldschool constructions,
but I would like to see more evolution and mixtures of both worlds.
Enjoy,
Michael