So I have this guitar on my bench that has a lot of back bow even with the truss rod completely loose, and no strings on it.
Apparently it was left in a shed for many years in some humid conditions. There was no strings on it (tuning machines were removed years ago) and the truss rod was left tight. Anyway, it has about 0.020" of back bow (measured at the 1st fret using a notched straightedge and feeler gauge).
Heres what I've done so far...
I used a fretboard heating blanket and removed the fretboard.
My plans are to install a stewmac double-action truss rod to help force the neck into some relief. It has a u-channel single action rod in it, like a Martin.
Before I substitute rods, I was thinking of:
1. Putting the neck in a Stewmac neck jig, forcing it straight with the peg head jack and pull down strap.
2. Then applying a bit of water to the bare exposed mahagony wood.
3. Using a few passes with a dry iron, I would steam the neck wood to help it conform straight.
4. Then leave it there for a few days to dry out.
5. Rinse and repeat if needed....
Any thoughts on if this would work? Has anyone done this sort of thing before with good results? Or maybe there is a better way??
Hope you guys can shed some light on this...
With the fretboard and trussrod off, I would heat the neck to shape. I would use a flat piece of aluminum the width of the neck, on top of that a small iron to heat the aluminum and the whole neck to about 80-90 degrees Celsius. With clamps and something between the table and the underside of the neck, I would bend the neck to about the opposite release it has now and let the heat reshape the neck.
This is risky business. The width of the neck will shrink and the contact points to the lacquer on the back of the neck may be affected by the heat. The desired straightness is not exactly what you will get unless you are lucky, but done right with some sanding of the neck surface and after gluing back the fretboard, it will be straight enough.
Maybe wetting the neck wood a lot and let time do the work, while bending the neck to negative release, will be effective, but surely not as quick.
I would also replace the trussrod with a carbon fiber rod, I don't like truss rods!
Damn right its risky business lol! Hard to always judge just where wood will want to settle with heat and water. But it's worth a shot considering the customer wants it done, and the neck is unplayable in it's current condition.
I've never heard anyone say they dont like truss rods before. You are a purist indeed lol. I actually was thinking that maybe some forced treatment of this neck might do it enough that the original rod could still be used. It is still in good shape and still operates. But I dont know if i want to take that chance. I'm hoping the combination of neck treatment, double-action rod, and even some sanding of the fretboard will get it back to a good playing condition again..... but obviously removing the least amount of wood, if any, is the goal.
Thanks for your input too! Cheers amigo!
I say that heat will bend the neck quite easily without the fretboard and trussrod. The old trussrod will work OK, a double action one is seldom needed.
Well. My opinion about trussrods are that they make as many problems as they solve. Metal is dead when it comes to tone and the extra weight of the neck is not beneficial for the guitar. They don't work as expected either, when compressing the neck wood the relief curve will have "mountains" and "valleys" due to the variation in the hardness of the neck wood, you don't get the smooth relief curve you expect. Then you have all the other assorted troubles with trussrods giving a buzz and other mechanical problems. The benefit of being able to fine tune the relief sometimes or never(!) comes with a price for the tone every day you play the guitar.
A glued in carbon fiber rod and a small relief sanded in the neck/fretboard will work very well. Carbon fiber don't creep (or at least very little) as wood and metal do. The rod and the neck will stay straight. The weight is about the same as the wood you remove. The tone of the guitar is not affected, at least not as much as a truss rod. The stiffness of the neck will be the same and don't change with the tension of the trussrod, high tension on the rod will make the neck stiffer and increase the "roughness" of the guitar - that is volume, attack, trebles and distortion in the tone. A loose rod will do the opposite.
I guess I'm a purist and I'm proud of it, but I'm not the only one with this view :-)