Double acting truss rods and fretwork

[Jon Cooper]

Hi all,

I've been lurking here for a few years and this is my first post.  I am a model maker/prototyper in real life but really enjoy working on guitars as a hobby.  I have done several refrets on Squire strats, made 4 or 5 nuts from bone blanks and done some electrical work.  Though you didn't know it, you guys have helped me through all of it.

I have an Epiphone ES-335 Pro that I'm working on right now and I have a question about it: With the guitar unstrung and the truss rod (double acting) in the "neutral" position the neck is backbowed.  This doesn't seem critical since it's a DA truss rod but in a perfect world should the neck be flat when there is no tension on the rod in either direction and the guitar is unstrung?  When strung and brought up to standard tuning the neck is pretty straight but the truss rod is sort of in limbo.

I want to refret this guitar and I'm considering taking this bow out of the fingerboard before I do. I am concerned about sanding through the block inlays in the middle of the neck since I have no idea how thick they are.  I'm guessing they're pretty thin.

Any thoughts?

Many thanks,

Jon

[Glen H]

In an ideal world, yes. But if the action is good, why "fix" it?  Just make very sure the fret tang size is the same as the ones you're taking out.

At least that's how I think.

[Greg Mirken]

Not a problem, generally. As long as the truss rod has a tiny bit of tension on it [in either direction] when the guitar is at pitch and the relief correct, it won't rattle. If it's dead loose it will rattle for sure.

[Russell Vance]

Hi Jon,

Depending on the fret dimension and the cleaned out fret slots there is always the risk of the neck changing it's tension (either way) with the installation of new frets.   Compression gives more backbow whereas slack fit can give more relief.   These are often matters of judgement and I guess one of the reasons that experience is a part of our tool of the trade.

That said the process of taking out some or all of the of the backbow prior to refretting is prudent with single action truss rods and probably good practice even with DA rods.   The plastic block inlays depth, binding depth and side dot position are limiting factors when removing material from the fingerboard to take out some of the excess.  The plastic block inlays on Epi's are over .060 thick normally so you can take a bit out of them - but beware the corners where they are thinner. 

For unfretted single action fingerboards the amount of quiescent relief when everything is neutralised is around .012".  This figure was given to me from one of the west coasts finest and major high end makers and I have used it as a base for making new boards/necks.  In application we use double action rods and reduce this figure to half that with our standard fret.  Refretting normally pulls the neck just about flat.

The necks usually pulls into  relief with "standard" string sets and tuning and it is reasonable consistent from rosewood to ebony and mahogany to walnut.   Surprisingly, a millimeter of neck thickness here and there doesn't seem to affect this action.   This para is for information only but it shows some of the factors you will encounter or should be aware of when dialing in relief prior to refretting. 

There is more, much much more to this and these are just a grab bag of thoughts as requested.  I'm sure my fellow forum members have a lot more experience to share on this most important subject.

Regards, 

Rusty. 

[Jon Cooper]

Thanks guys,

This is very helpful to me.  I'm going to refret and try and make it as textbook as I can while doing it. After all, I bought this guitar, in part, with the idea of it being a learning tool for me.

Thanks again,

Jon