Clamping a neck into a back-bow

[eliya]

Hello everyone, I'm new to this board and also fairly new to guitar repair. I tried using the search function to find previous threads about the subject, but came up empty handed (I'm sure it's been discussed, but I just couldn't find it).

I have a Guild S300 (24 frets, 24 3/4" scale, set neck) that has a set of 11s on, and even with the truss rod maxed out, the neck isn't straight. Instead it has an up bow, which isn't drastic, but probably too much for my liking. I plan on bringing this guitar back to a playing condition (including a refret), but first I want to get the neck straight. I've seen Dan Erlewine demonstrate clamping a neck into a back bow in one of his videos, and he made it look easy and like something that's done more often than not. However, he doesn't go into very specific details.

How loose/tight do you keep the truss rod nut?

Do you clamp with or without strings on? (With strings seems to make more sense)

How long do you clamp it for?

Is it really something that's done more often than not?

Is this the right thing to do in order to get the neck straight? I've also seen the method of pushing down on the headstock while turning the nut in order to bring the neck into a back bow. I'll probably try that first.

Some helpful info about this guitar: It is a real road warrior. Its frets are worn all the way to the 14th fret, and the finish is almost completely missing from the back of the neck. When I first got it it had too much back bow, and the luthier who used to work on my guitars suggested stringing it with heavy strings to compensate for that. I used to use 013s with it (but tuned low) and went back to 011 in the last two years. I don't know if the neck's ability to go from one bow to the other is a good or a bad sign, but I thought I'd mention it.

Thanks! I really enjoy this forum.

[Jeff Highland]

When you say the truss rod is maxed out, is it coming up to a hard stop (running out of thread) or is it just harder to turn than you are comfortable with?

An extra washer in the first case and possibly lubrication may help

[eliya]

It's coming to a hard stop. That is, I can see that the nut is maxed out. Like with any nut or a screw that reaches the end of the thread, it's possible that I could squeeze a fraction of a turn out of it, but it's not worth the risk.

I've heard of the extra washer solution before, but never understood the mechanics of it. Why would the extra washer make it easier/safer to straighten the neck?

[Jeff Highland]

An extra washer gives you another turn or two before you come to a stop and gives the extra tension associated with that

[Kerry Krishna]

Heat pressing a neck is not an easy thing to do and it STAY done. I have done several in the last 20 years. Many (not all of them) needed to be done several times, the main reason being that the neck is  'remembering ' were it used to be.

 I have a setup that I built were I got a piece of 1/4 inch thick brass  that was 1 1/2 inches wide, and disassembled ,customized, and reassembled an iron . It now does double duty both for this particular job, and for removing fretboards. 

 So, the strings come off, the customized iron goes on, it heats up slowly until the back of the neck gets hot, then all the clamps and wedges that you had already done the 'dry test' with that are sitting right there get put on and the reverse arch is applied. You wait until the neck has 100% cooled down (an hour?) and take it off and see what it says.

 I had one neck about 3 years ago with no neck reinforcement at all that took 7 times doing this until it 'stayed' were I needed it to be. It was a full two day job, and more frustrating than I care to talk about. 

 You also have to overclamp the arch, because it will certainly want to spring back to it's old shape.

 There os no getting around the refret job either. Many times, it will involve a fretboard planing too, so you have to have you .0023 thou fretslot saw ready to deepen the fretslots that are planed out. 

 All in all, this is not all that easy, and I would leave it to a pro who has done it before. There are several things that can seriously go wrong, like melting the binding on the neck, melting the inlays,  burning your house to the ground. 

 I kid you not on that last one. If you have an iron turned on/ or a heat lamp on something, turn off the bloody phone, don't start watching TV or vids, just keep your nose within about 10 inches of the thing to smell plastic starting to off gas, of wood starting to burn.

[eliya]

Thank you! This is very informative. I should have mentioned it in my original post, but I meant a "dry" clamp, i.e. no heat or anything. It sounds though from what you're saying that this method is even less effecting than clamping with heat.

[LARRY KLOSE]

To enlarge your knowledge base, take a look at Frank's www.frets.com and Dan Earliwine's articles on the StewmMac web site for tips.  One thing I did on a guitar with this problem and a neck so resistant that it caused me to strip the rod threads the first time I  tried was to clamp the neck  to a backbow as Dan shows, then tighten the nut on the rod with no pressure on the rod (after I had the threads repaired).  Another thing I learned is that if the guitar is in a dry environment the neck can tend to bend from fretboard shrinkage and string tension.  Take it into a more humid environment where the board expands a little and it may adjust easily--after adding a washer or two if it's bottomed out.

I have an inexpensive flamenco guitar I bought in Spain that had a neck with too much relief and no rod.  It took two hits with heat treatment to get it to settle in. 

Larry

[Mark Pollock]

I would suggest using a deadman switch with a heat lamp, that way if you leave, it turns off.

[Robbie Collins]

One thing you might want to try is to take the truss rod nut off, lubricate its inner threads with vaseline, put on the washer(s), replace the nut but leave it loose.

Then find a straight piece of hardwood (like oak) as long as the fretboard, say, .75" x 1.5" x 18" and a couple of hardwood blocks - one that will fit between the nut and first fret and another that will fit between two frets above the neck-body joint. Otherwise, make them about 1.5" square.

Place the blocks between the frets and rest the board on top. Place a Quik-clamp upside down with one padded jaw under the 9th fret and the other on top of the board. Apply enough pressure to bring the neck into a slight backbow.  Now, tighten the truss rod nut until firm and remove the clamp and boards. The neck should, with no other problems, remain in a slight back bow. You can now loosen the truss rod nut in small increments until you have the right amount of relief.

[Jeff Highland]

You will still need the extra washer with this method if the nut has come to the end of the threads on the rod

[Jeff Highland]

If, as you have suggested, you are intending to refret, this will also give you an opportunity to level the board, so heat treatment is probably not appropriate. Focus at the moment on getting a functioning truss rod.

[eliya]

Thanks Robbie, I will try that.

Does it really make a difference what washer I use? The washer it has right now is a half moon washer like Gibsons have. I also have a Fender neck that will need some clamping, and I assume it doesn't require a special washer (or does it?)

[Jeff Highland]

Just a regular small round washer between the nut and the existing half moon