Correcting Warped Neck...........

[Jack Wells]

I was looking at Complete Guitar Repair by Hideo Kamimoto. To correct warped necks he suggests using spacers and clamps and a thick piece of hardwood. He suggests heating the neck before clamping it. I think the reason for heating is to soften the glue holding the finger board to the neck allowing the two pieces of wood to move with respect to each other.
What about a one piece maple neck? Would heating this type neck do any good?

 

[Guitarslinger1]

Take this guitar to a local luthier.

 

[Jack Wells]

secialty guitars..............

I asked a specific question regarding a specific issue. You give me the most general answer that is applicable to every guitar problem. The purpose of this forum is to exchange information and knowledge. Do you have information or knowledge related to my issue?

 

[LouisianaGrey]

Well, I think Specialty Guitars was probably asking the question in your signature tag. The fact that you are asking this, especially giving such little detail, suggests that you may not know enough to diagnose your problem correctly or to execute whatever repair may be necessary, so I agree with him.

The answer to your question is that heat is used when bending any kind of wood, sometimes in conjunction with steam, sometimes not. The only kind of glue that is softened by heat and will re-bond is hide glue. The other kinds of glue used in guitar construction (typically aliphatic) can be removed with heat - for example you would heat a fingerboard to remove it - but then you have to clean up thoroughly and use fresh glue.

 

[Jack Wells]

OK................. let me be more specific. This is a single piece maple neck with no separate fret board so the glue softening does not apply. The neck has taken a permanent forward bow that cannot be adjusted out using the truss rod adjustment. I've reached the truss rod adjusment limit. The truss rod nut cannot be easily removed to add washers because a rosewood plug with a small hole was glued in after the truss rod nut was installed. I will probably drill out this plug and add washers but first I want to make the neck straight.
The neck has a polyurethane finish so I don't see how steam would have an effect. I not that familiar with wood bending so I'm just asking if heat will help in this specific situation.

The block is oak. The spacers are redwood........ very soft.

 

[LouisianaGrey]

That set up looks to me like it should work OK, but if that's just foam on the back of the neck then I think you'll find the clamps will dig into the wood. I'd use a shaped block of wood if it was mine. Don't forget to slacken the trussrod before you tighten those clamps.

I wouldn't get too hung up on the idea of heat - just clamping should work OK if you leave it long enough. You would really need to use a heat blanket or something similar in that situation and you could easily end up spending as much money as it would cost to buy a new neck.

 

[Guitarslinger1]

Neck

I field many emails each day from people wanting to do all sorts of things themselves to their guitars, that some should not be doing. I must have been in that mode when I responded to your post. My apologies for getting in your way.

The walnut plug in the headstock does not need to be drilled out. It can be removed. The finish around it is scored with a razor knife, and then the plug is gently heated to break down the glue. The truss rod nut is gently backed out to push out the plug. There are of course some risks involved with this sort of thing, such as scorching the finish while heating the plug area, and the plug will probably be destroyed.

Fender has a specific tech note that steps this procedure out. It may be on their website, I don't know. You can call Fender and ask them to fax or email it to you. If the phone rep has no idea what you are asking for, ask him to ask one of their guitar techs. Replacement plugs and truss rod nuts are available, as are the washers, but chances are that they will only send them to an authorized Fender luthier.

I agree with Louisiana that the heat may not be needed, or even the clamping for that matter. I know I would try adding the preload washers to the truss rod nut, and then see if the bow could be adjusted out first.

 

[Kevin]

When I straighten necks out with an upbow, I clamp them in the opposite direction of what you show.

That is, I face the fingerboard down and support each end on a block of wood. Then I machine a piece of wood to match the back contour of the neck, but be flat on the other side. I place this piece of wood on the back of the neck in the area of the bow. Clamp down.

The spacers should be used, IMHO, only to "replace" compressed wood. If the wood is compressed, that means the rod was over-tightened. If the rod was over-tightened, that means that someone was trying really hard to pull out a bow that the truss rod wasn't correcting.

You should straighten the neck, and then use the truss rod to keep it straight. In other words, I'd definitely "help" the neck into a straight line with a clamp, rather than relying on the truss rod to do it for me.

Again -- somewhat along the lines of what I thing Sp. Guit. was getting at -- and the same warning I posted to a nearly-identical question last week -- don't do any of this if you don't know what you're doing. Guitar necks will break if you apply too much pressure with clamps. If you're unsure, take it to someone who knows how to do it.

 

[Jack Wells]

Thanks ..... LouisianaGrey and specialty guitars......

Now that's the kind of advice I was looking for. By the way, that's a very stiff piece of foam ......... more like thick rubber.
Specialty guitars.........I really appreciate your advice on the plug removal. I have the replacement plug and washers. A previous owner had tried to remove the truss rod nut resulting in cracks to the finish around the plug so I will have some cosmetic repairs to do also.

Thanks to you too Kevin.

 

[Jack Wells]

Kevin...............

You wrote:

When I straighten necks out with an upbow, I clamp them in the opposite direction of what you show.

That is, I face the fingerboard down and support each end on a block of wood. Then I machine a piece of wood to match the back contour of the neck, but be flat on the other side. I place this piece of wood on the back of the neck in the area of the bow. Clamp down.

I assume you are clamping down to a table or work bench. Isn't my clamping method essentially applying force to the neck in the same direction?
image removed

 

[Guitarslinger1]

Kevin, you make a very good point. If the neck is really bad off, then working with it prior to adding the washers is probably necessay. If it is just a hair or 2 away, the washers might be enough to get it there.

 

[dean]

I did that!

I had a cheapo neck that was severely back-bowed - the opposite of what your picture shows. I rigged up the clamps similar to what the picture shows, but I used a shaped block instead of the padding. I did not heat the neck, although the process would probably have been speeded up if I had. I ended up leaving the neck in the clamps for a few months, and that removed the bow. The neck is sitting in a box right now, and it has not re-bowed - I think it will be OK when I get it on a guitar.

The heat seems to help, though. I once had a hollowbody with a twisted neck that I straightened, and that definitely needed heat. One source said that the heat not only does the glue thing, it also works on a molecular level to help alter the "memory" of the wood grain. Maybe . . .

Good luck with the project - let us know how it evolves.

Dean

 

[Kevin]

Up/down probably doesn't matter.

The single clamp, though, IMHO, would exert a more consistent pressure than two clamps. I also use a table/workbench as the object that I'm pulling the neck towards (your 2X4 in your pic), and that's pretty much gonna be underneath the neck.

 

[playin loud]

Would it be better to take the neck off the guitar :?: Of course I am only speaking of bolt on necks

 

[Jack Wells]

The neck doesn't come off this guitar otherwise I probably would. I am using the two clamps because thats what is shown in the book I referenced above. The author suggests one at fret 4 and one at fret 7.