12 fret OOO neck problem

[Randy Roberts]

I’ve got a problem that I hope you folks will tell me is not as big a problem as I think it is.

This is a neck that I made 5 years ago. It’s 7 piece laminate with about a ¼ inch maple center skunk stripe.
About 6 months ago the brother in law I made it for noticed a slight ridge that he could feel at the edge of the skunk stripe, and didn’t say anything about it until I borrowed the guitar to show it to someone today.

The slight ridge is actually on both sides of the center maple stripe, starting midway between the level of the nut and first fret, and extending to near the third fret. There is nowhere else allong the neck where this has occurred. The neck has 2 CF beams about ½ inch outboard of the centerline, and a Hotrod truss rod accessed through the Soundhole.


I think I know what the cause of this problem is and if I’m right, I’ll need your advice on remedies, as I’m an amateur builder and haven’t tackled repairs before (well… I guess my building method is pretty much one long continuous repair).
To keep everything objective, I’ll show what the problem looks like but wait a bit with my guess as to what’s gone wrong so as not to bias you guys’ thinking.

[Mark Swanson]

Hi Randy!
That area is (in my opinion) not in the highest stress area of the trussrod, and a Hot Rod doesn't push down in its slot like a single trussrod would. Plus it isn't a long enough area to be caused by the trussrod. You'd need a pretty tightly cranked single action rod to have it push hard enough to do that in that place, and it would probably happen more in the center of the neck for that to happen.
This looks just like a little movement in the maple to me. You have a lot of laminations there and the maple isn't as stable as the surrounding wood. That ridge doesn't look that bad to me and you could probably get away with leaving it alone, or just sand it down and refinish the area and be fine.

[Randy Roberts]

Thanks for the quick reply Mark.

I fished through pictures from when I built this one, and ran across this one, and wonder if this changes your opinion.

Purely by chance, the trussrod slot was almost exactly the width of the maple. (I remember thinking at the time how neat and tidy it looked). I'm wondering if this means that instead of a glue line ( LMI all wood epoxy) as wide as the neck is thick, on this one it's only the remnant of maple left after the slot was cut that's glued to the adjacent wood.

I'm worried that the constant pressure from the truss rod is causing cold creep in that glue line because of the glue line being much less than normal surface area. It looks to me that all the force of the truss rod would be born by this thin glue line instead of the matrix of the wood like it would be if it was a regular neck or ifthe center stripe was narrower.

The rise of the maple above the surface of the rest of the neck starts just about right where the threads are coming out of the brass end block of the truss rod in this picture.

The truss rod is only being used for relief in this neck, not for any action adjustment (this is one of those Doolin adjustable necks) and I'm certain the owner hasn't messed with the rod any, so there's not that much pressure being applied originally by the rod, but over 4-5 years with the bend of the neck with string load...

[Mario Proulx]

Randy, I believe you have it figured out correctly; without the second set of photos, I would have agreed with Mark, but seeing how the rod works on the maple-only, and seeing as how you used epoxy(all epoxy cold creeps, quite a bit!), methinks your conclusion is right.

The fix? As Mark said, live with it(it's likely barely discernible to the player's hand, right?), or a wee bit of sanding and if you're lucky, you have enough finish to just buff it out, or at worse, touch it up. I don't think it will self-destruct any time soon.

We can all take a lesson from this, though; if we're gonna add a "skunk stripe" to a neck, make it a good bit narrower, or wider, than the truss rod.

[Mark Swanson]

Now who could argue with that?

[Chuck Tweedy]

With that much carbon in the neck, you should be able to completely back off on the truss-rod and stop that creep! <g>

[Randy Roberts]

I can’t begin to thank you guys enough…. I’d already started trying to figure out some set of jigs to 1. Heat only the area involved, 2. Apply pressure to the raised area to realign it, 3. Somehow separate the fibers of the outer laminations enough to insert a steel sheet “bridge” laterally exactly under the face of the trussrod to transfer the load out to the outer wood, 4 reappose the separated fibers invisibly and , 5.Bob’s your uncle. After all if you can’t make something difficult what’s the point of doing it at all.<g>
For some reason your ideas sound a little better.

I’m going to loosen the truss rod, sand the raised area down and refinish it (French polish so no sweat…now I know why I went through the frustrations of learning how). And, of course,explain to him the warrantee expired last week… if he’d only have called sooner.
Again, I can’t thank you guys enough.

p.s. Mario, the " we can learn a lesson from this" is part of why I posted this. It never crossed my mind for an instant that I was creating a potential problem for down the road when I did this. that's what makes this forum so valuable.

[Ron Belanger]

I have a similar problem with one of my necks. I was at an outdoor show and the wind blew it off the stand. As with yours, the carbon fiber runs into the headstock and initially there did not appear to be any damage, but lately I noticed a small bump and a crack. The CF prevented a break, and I should be able to deal with the crack with a little CA.