Martin CEO-4R back bow .

[Len Biglin]

Hi all , this concerns a limited edition martin "CEO's choice dreadnaught . The neck has a back bow with no tension on truss . Fretboard is micarta , neck is mahogany , wonder if neck has dried and shrunk while board stayed put ? Anyway I'd say its  dead straight but plays like it has a back bow , in standard tuning with 12-56 . Action is a little low as per straight neck . I don't think the frets should be dressed into relief , would I be ok to heat and clamp the neck into some relief ? The board is lacquered on the edges . Im a little worried about heating micarta too much . Any suggestions ?

[Hesh Breakstone]

Hey Len:  This one must be old enough that Martin was not using their double action rod yet, eh.  We see a lot of back bowed Martins in our climate and it's usually because they dried out.  Fret sprout is also a symptom of this.

I'm not a fan of heat treating because there is no telling if it will take over time or if the thing will come back with the same issue.

My suggestion is to mill in relief as you already thought that you might.  We level with calibrated leveling beams and when I want to add relief I press slightly on the head stock with the neck supported under the 7th while sanding with the beam the frets in the region that I want the relief.  In this case I would level the frets level on the treble side counting on string tension to provide some relief.  On the bass side while leveling I would gently press on the head stock to make the frets 3 - 10ish slightly proud and let the beam hit them and mill in relief.

In other words reshaping the fret plane would be my preference and it's a fix that will last.

Good luck.

[Len Biglin]

Hi Hesh , nice to hear from you again , I guess that makes sense , seeing its actually dead flat now it won't need much dressing . It is a single action rod . Thanks Hesh.

[jbbancroft]

I’ve found that a neck with up bow is generally caused from high humidity. Low humidity will cause the opposite effect or more relief which the truss rod will correct.

you could loosen the truss as much as possible, place a 2”x2” block the length of the fretboard with a slight shim in the middle and clamp the block at both ends. This will bow the neck in the opposite direction.

you could add a little heat by wrapping the neck in a heating pad on either low or medium heat. Let this sit for 3 to 5 days then check neck, let is sit longer if needed.

Jim

[Len Biglin]

Thanks Jim , I'm considering that too .

[jbbancroft]

If the neck is actually dead flat, the simplest repair would be to install a higher saddle. But if the fretboard has a crown, or bowed up, then that needs correcting.

Jim

[Len Biglin]

With strings off it has a radical back bow from sound hole to nut , Ive advised the owner to return it , he has that option .