Bob-Dubery
A regular truss-rod I understand. But what's with these double-action rods and what are the pros and cons?
AlanRatcliffe
A double-action (also called bi-flex) truss rod can be adjusted to bend either way to cure excess bow or relief. They are stiffer and more rigid than a conventional single-action truss. The downsides are they are twice as heavy and add a lot of brightness.
I'm not a fan - it's rare that a decent neck needs adjustment to get rid of bow and I prefer the tone of the single-action truss.
g1
IMO, I don't think the truss rod will effect the tone. It might effect the weight, but I have seen some ordinary truss rods that are heavier than some dual-action truss rods. I've used both before.
A dual action truss rod might be useful if one uses very stiff woods for the neck. If one cuts very narrow fret slots for the frets it can cause back bow.
My personal opinion is that having adjustment both ways is useful but certainly not necessary.
Gearhead
Interesting topic. I'd like to know your opinions on the truss rods for sale:
LMI for electric
LMI for steel string
StewMac for electric
StewMac for steel string
...others?
Getting parts together for a steel string build, at this point I was thinking along the lines of just making a truss. I would go Martin-style and get a piece of U-shaped alu extrusion, weld in alu blocks on either end and put a threaded steel insert into one of them. The rod itself can be roundbar 10mm that I tap M10 into.
Would it be an improvement to get carbon rods and glue them in alongside the truss? Do they only brighten up tone or can I expect more?
AlanRatcliffe
I've always used the LMI single trusses, which are good - simple and effective. I can't compare to the Stewmac as I've never used them.
The carbon rods make the neck a lot stiffer and brighter. Not needed in most cases (overkill), but sometimes nice when you need extra reinforcement (really skinny necks, multi-string bass necks). Vigier uses a single rod to completely replace the traditional truss rod - but that is non-adjustable, so you better make sure your wood is well cured.
Gearhead
Yeah I've also seen carbon hollow bars, square on the outside with a round bore, through which a traditional truss would go. Incredibly expensive though, plus I am not so sure whether the truss would actually give enough control.
Will stick with the modified Martin plan for the acoustic and see about LMI later.
Thanks ?
g1
I've used both the Martin-style u-channel from stewmac and the hotrods from stew mac. Both seem to work great, both easy to install, and provide effective adjust ability.
I'm not sure what my opinion is but some people think that using carbon fibre rods doesn't make sense. Their opinion is that the whole point of the neck is that it is adjustable and that adding extra stiffness (with carbon fibre) just takes away from the adjust ability.
I used carbon fibre rods with a martin style rod for my recent 6 string bass build. The neck has hardly budged with the strings on (and it's a longer than normal scale).
But I doubt carbon fibre is really needed for a guitar (as a posed to a bass).
