It seems to me that the standard truss rods are designed for 34" scale instruments. So what does one use for a 35" scale design?

same truss rod as for 34"

What about for a 37" scale?

I'm working on a 37"-34" fanned fret bass neck, and I'm planning to use a Stew-Mac hot rod with a spoked adjusting nut (link (http://www.stewmac.com/shop/Truss_rods/Adjustable_truss_rods/4/Hot_Rod_Truss_Rods.html)). I would like for the adjustment nut to poke through the fingerboard, bisecting the 23rd fret. If I do it that way, the end of the rod will only reach to the first fret, whereas most truss rod installations I've seen go to the nut. Could this cause me problems?

Here is a picture of what I mean. Click the image for a bigger view. (and no, I'm not chopping up my Dingwall)

http://www.ece.utexas.edu/~wrobert/dw_tr_small.jpg (http://www.ece.utexas.edu/~wrobert/dw_tr_big.jpg)

Hi, i maybe wrong but i heard that Clif bordwell's trussrod are slightly longer than the others... You should visit is website and give him a call or send him an email.

People tend to like his trussrods... he sells them too!

www.cbbasses.com

Francois

I feel like truss rod action is not exact enough to worry about even a couple of inches. Most necks bow in the first seven frets, where there's less wood than further up. Trussrods have the most effect in the middle of their length it seems to me, and the middle isn't necessarily going to correspond with the spot on the neck where the bowing is worst, whether the rod is 24" or longer. In fact, an argument could be made that a longer trussrod would be worse, since its center is further up the neck and further away from where the bowing problems are worst. Take this view further and you might choose an 18" trussrod running from nut to the 12th fret to put the most action where the problems are greatest. Overall though I just don't believe it makes much difference in the real world and isn't something to spend much time worrying about. My idea of the action of the trussrod may be wrong (what do any of you actually knowledgeable people think?) but in practice they just seem to work pretty well but not perfectly regardless of the details.

So, if I were to use a standard length truss rod, this implies the adjustment needs to go at the headstock...

That's the way it makes sense to me, but plenty of basses much nicer than the ones I've made, built by people with much more experience than I have, have the adjustment at the end of the neck. Again, my feeling is that it's a very inexact science (or maybe it's an art), that it'll work pretty much the way it's supposed to regardless, and that it's a pretty small consideration compared to most of the other decisions to be made about the instrument. Just my opinion. There may be some people with very strong views one way or another about it.