2 way truss rod...how does it work?

[cofibreyk]

http://www.stewmac.com/shop/Truss_ro...russ_Rods.html

it says here that the active rod is below the passive rod, ok.
how does this help in giving a much better backbow?
...and i don't see why anyone would want an upbow? cos it says that it can also correct upbow. don't you just have to loosen the t/r to have an upbow.

thanks

[jrfrond]

You don't want to upbow a normal neck, but if the neck that you are building from scratch is stiff and has no relief, or not enough, you can make good use of a dual-acting truss rod.

[cofibreyk]

i see. so there's such a neck wood that is stiff enough that has no or not enough relief even with strings on 'em. what kind of wood?
now on a normal neck wood like maple, how does this 2way rod improve stability in straightening a neck? or is its advantage is only in correcting an upbow?

[punkrocko]

You’ll want a certain amount of relief in all necks. Some multi laminate necks are stiff enough that the string tension won’t pull the neck into relief. Some strings (TI’s) are low tension and won’t bring the neck into proper relief. With a dual action truss rod it’s easier to overcome these scenarios.

I’ve used the Hot Rod in the past and it works great. It’s easy to install (and remove if need be). Make sure you get the router bit for it as it is an unusual size. The only down side is it requires a deeper channel to accommodate both rods. This may or may not be a problem for you though.

[Rodent]

unless you're utilizing the spoke wheel adjustment nut model, I'd highly recommend the Luthier's Mercantile trussrod over the StewMac Hotrod. the LMI trussrod utilizes a standard router bit width, is significantly less weight, and it sits a full 1/16" shallower

here's a link for the TRBSD model used on bass necks:

http://www.lmii.com/CartTwo/thirdpro...ion+welded+nut

sure it's $6 more than the Hotrod - but it's $6 well spent

all the best,

R