Ok to use a 16.5" 2 way truss rod on an lp neck build?

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Greg Martin
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Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by Greg Martin »

Ive always used an 18" truss rods for all my guitars, but a retired repair man gave me 7 each 16-1/2" , 2 way truss rods. Im wondering if they would be long enough for electric guitar builds. What say youall ?
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Dan Smith
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Re: Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by Dan Smith »

I use 16” all the time.
I don’t like the 18” rod going to the end of the fretboard, but I don’t have a good reason why.
I suspect the midpoint of the rod will be where the relief will be asjusted on the fretboard.
this ends up around fret 7 or 8 with a 16”rod depending of scale length.
Ever-body was kung fu fight-in,
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David King
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Re: Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by David King »

I would encourage you to stick with the tried and true -a single curved rod. Build some relief into your necks so you won't ever need to use the forward bending capability which even on the best two-way rods is weak . Do stress-test your two-way rods in a confined slot to make sure they won't fail in the neck. Some are notorious though in recent years they've gotten a lot better.
Freeman Keller
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Re: Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by Freeman Keller »

It probably would be OK. I've built two LP's and two 335's and always used 18 inch rods - both LMII and StewMac. Here is a SM rod in a LP neck the first line is the neck to body joint (fret 16). You can see where the end of the rod is relative to that.

Image

Here is that same neck in the body without the rod - if you move the end of the rod 1-1/2 inch it is still going to be over the neck heel

Image

That should work fine to control relief up to the heel (fret 14 or so) - after that it doesn't have much effect.

Btw - I use double acting rods in everything and they seem to work fine. A recent article in AL felt that single action curved rods were better - you can make up your own mind.
Greg Martin
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Re: Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by Greg Martin »

Thanks. I wondered if a shorter rod like the 16.5 would have best curve in the 6-7-8 fret area instead of the 8- 9-10 fret, of the 18" rods. and the rod over the heel probably does little . Im glad i can use them. Ill test each ,because i feel they are a few years old and maybe not as good as modern made units.
Chris Richards
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Re: Ok to use a 16.5" 2 way truss rod on an lp neck build?

Post by Chris Richards »

If vintage accurate is not your main concern then I would always use a modern two way rod, I used to use the traditional arrangement exclusively but started using the bi flex rods a couple of years ago, I just think that the way they work is a lot kinder to the neck since the bending action is transmitted to the neck along the whole length of the rod without stressing/crushing the wood at anchor points etc.

Regarding traditional rods it's quite surprising, especially in a Gibson neck how close to the back of the neck the rods are at their deepest point and this is usually around the 7th fret where when tightened will exert the most force, a bi flex rod is going to bend the neck most at the centre of the rod, like you say you can adjust this by using a shorter or longer rod.

Bi flex rods are far easier to install and retain more wood/strength around the nut area, when I install them I "stick" them in with some silicon being careful not to get any on the fb gluing surface so any possible rattle is prevented.
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