Stealth truss rod mod for my old archtop
Posted: Mon Mar 11, 2013 1:25 am
I had decided that before building anything else I should tackle some resto/repair projects. This Harmony Monterey has been sitting there pretty, but unplayable since I got it about 3 years ago. Lovely old (1935-40) thing all original down to the last screw, one owner all it's life until a few months before I got it. Seriously bent neck though, and I was trying to come up with a way to fix it without any visible changes (like a truss rod cover). I had the brainwave for this when I was making another neck with a spoke adjuster nut. Measuring it made me think it could probably be tucked out of sight under the nut on this old girl. So one night I pulled the frets out- no turning back after that! 
Even that was a mission, the board splintered and chipped no matter what I did, so it took some work to repair.
Here's what I found when the board came off- there was a steel reinforcing rod (didn't want to come out, needed a drill down the sides to loosen) but it never did anything, because the channel was about 3-4mm deeper, so the neck just bent around it. Awesome.
Routed out for the truss rod (to be filled again, and a curved channel routed in):
Next, some carbon fibre epoxied and clamped in (straightened the neck a little bit):
Improvising all the way on this one. How to rout a truss rod channel with the neck still on the guitar? I ended up making a bendy jig clamped on/ around the neck:
Here it is with the cavity routed, rod in, etc. The rod is compressing on to the carbon fibre at both ends, I didn't want it compressing the softish wood, and the adjuster slowly disappearing under the fingerboard. One trick I learned through a mistake- making a 12-string neck a while ago, I was worried about the neck being rigid enough, so instead of cutting the wood that glues in over the truss rod channel into a matching curve, I left it straight and forced it in with clamps. It was total overkill, and created a backbow that I had to "engineer" out. I tried the same thing on this neck, and it forced it straight. I left it a few days before finally glueing it in, it seemed stable so now it's in there. Weeks later under string tension, the neck hasn't moved in any direction.
Board back in place, getting leveled and 7.25" compound radius:
Frets in getting tidied up:
End result- lovely old vintage guitar, with super low action, and really nice to play, totally worth all the effort. (I'll have to repair the finish on the neck- I used a steam iron the remove the board, but I didn't check it first- the steam wouldn't shut off, and I've messed up the original finish )
Glamour shot with DeArmond FHC pickup in place. The only downside is that this guitar has very little clearance between the strings and the body, so I can't slide the pickup closer to the neck without raising the action. Cool tones as it is though,
a bit like this.
Even that was a mission, the board splintered and chipped no matter what I did, so it took some work to repair.Here's what I found when the board came off- there was a steel reinforcing rod (didn't want to come out, needed a drill down the sides to loosen) but it never did anything, because the channel was about 3-4mm deeper, so the neck just bent around it. Awesome.
Routed out for the truss rod (to be filled again, and a curved channel routed in):
Next, some carbon fibre epoxied and clamped in (straightened the neck a little bit):
Improvising all the way on this one. How to rout a truss rod channel with the neck still on the guitar? I ended up making a bendy jig clamped on/ around the neck:
Here it is with the cavity routed, rod in, etc. The rod is compressing on to the carbon fibre at both ends, I didn't want it compressing the softish wood, and the adjuster slowly disappearing under the fingerboard. One trick I learned through a mistake- making a 12-string neck a while ago, I was worried about the neck being rigid enough, so instead of cutting the wood that glues in over the truss rod channel into a matching curve, I left it straight and forced it in with clamps. It was total overkill, and created a backbow that I had to "engineer" out. I tried the same thing on this neck, and it forced it straight. I left it a few days before finally glueing it in, it seemed stable so now it's in there. Weeks later under string tension, the neck hasn't moved in any direction.
Board back in place, getting leveled and 7.25" compound radius:
Frets in getting tidied up:
End result- lovely old vintage guitar, with super low action, and really nice to play, totally worth all the effort. (I'll have to repair the finish on the neck- I used a steam iron the remove the board, but I didn't check it first- the steam wouldn't shut off, and I've messed up the original finish
)Glamour shot with DeArmond FHC pickup in place. The only downside is that this guitar has very little clearance between the strings and the body, so I can't slide the pickup closer to the neck without raising the action. Cool tones as it is though,
a bit like this.
The steel in my archtop's neck put up a fight too, I had to run a drill down both sides for the full length, then chisel some wood out at one end so I could get some vice grips on to it. The ironic thing is that if the slot had been cut to the correct depth in the first place, the steel would have done it's job, and probably none of my work would have been necessary. Good learning curve though, and I won't be afraid of any more bent necks if they come along (not that there are many old Harmonys/ Kays etc to be found in NZ anyway)