My gosh, what an offer! I hope someone does this. If I was retired, I probably would!
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Scary Neck Repairs: Two Wal Necks
- Thread starter Bruce Johnson
- Start date
My gosh, what an offer! I hope someone does this. If I was retired, I probably would!
is there some method used to be able to tell how far the truss rod has been turned? How can you tell when it's at 50%? Thank you!
No, there isn't really any accurate method. I suppose someone could put a small torque wrench on there and measure how many inch-lbs it took to break a rod, then go with half that number. But there's a lot of variation in the twisting frictional drag from one truss rod installation to another, so it would be hard to get consistent torque numbers to recommend.
The important thing is that the truss rod is tightened enough that it is fully applying load to the neck, and has begun to bend it. I've found, by years of experience, that getting to that point requires tightening the rod about halfway as tight as it would take to snap it off. That's where my 50% guideline number comes from.
Whenever I build a new neck, I always test it by tightening the truss rod to about 75% Forward and about 50% Reverse. By eye and with a straightedge, I verify that the neck is actually bending back and then forward. Then I return it to 50% forward, and keep it there while I do the final leveling of the frets.
I'd think the only real way to measure something like that would be a straight edge notched for the frets (which I think you can get, or make one yourself). That way you could see the rod act on the neck and set relief indepent of the fret heights.
I've never really found a use for those notched straightedges. When I'm leveling the fingerboard, the frets aren't in it yet. I use a straightedge to check how straight the neck is. After the frets are in, I use the straightedge on top of the frets. The frets are now the top surface of the neck. Once the frets are in there, I don't see the point of measuring the straightness of the fingerboard surface.
I've asked other Luthiers and Techs what they use the notched straightedges for, and never gotten a good answer.
I've thought about taking some of my most popular technical threads, like this one, and editing them into Wiki threads. TalkBass has the Wiki section, which I haven't used much. I could start putting up technical articles on there, several pages on one subject with good pictures and text flow. Descriptive titles that are easy to find in a search. That could be a useful research library for Luthiers.
what makes sense for me (as a fixer, not a builder) is to use the notched when i can't "trust" the fret tops, like when i'm leveling an existing neck with worn frets or just a neck with a slightly high fret here and there.
one high fret in the middle of an otherwise perfect run would cause a full-length straightedge on top to rock and might lead me to adjust the neck away from truly straight before leveling. that would still leave me with a perfectly straight fret top profile but maybe not a matching fret board profile
here's a ridiculously exaggerated drawing somebody else did of what might happen if you level fret tops without properly controlling for the fretboard straightness under them
what makes sense for me (as a fixer, not a builder) is to use the notched when i can't "trust" the fret tops, like when i'm leveling an existing neck with worn frets or just a neck with a slightly high fret here and there.
one high fret in the middle of an otherwise perfect run would cause a full-length straightedge on top to rock and might lead me to adjust the neck away from truly straight before leveling. that would still leave me with a perfectly straight fret top profile but maybe not a matching fret board profile
here's a ridiculously exaggerated drawing somebody else did of what might happen if you level fret tops without properly controlling for the fretboard straightness under them
Hey Walter;
Okay, I understand that. But I have to ask: Does it matter if the fingerboard surface is bowed or lumpy, as long as the tops of the frets are all level? What difference does it make to the function or playability of the instrument?
If I'm handed a neck that needs fret leveling, my main concern is tightening the truss rod halfway to make sure the neck is being loaded by the truss rod. Then I'll visually check to see if the neck, in that loaded condition, is close enough to flat to be able to level the frets. If it's in that range, then I'm not really concerned with how flat the fingerboard surface is. I just level the frets.
If the surface is far enough out of straight that I can't level the frets, then I pull the frets and level the fingerboard surface. Still at that loaded condition.
It's the loading that's important. Making the frets level with no strings and the truss rod halfway tight. That makes the neck stable and easy to adjust.
the idea is that in more extreme cases it might, you could end up with frets that are essentially taller or shorter in one area than another area, throwing off the feel. maybe it's more of a thing for guitar players who like to bend and want taller frets for grip, fret height can matter a whole lot
sure, no doubt! unless it's a vintage neck that you don't want to disturb the fretboard wood on, if the board itself is uneven then best to true it up first, that way the fret tops need far less leveling after they're in
either way, the notched is for confirming the wood itself to be straight (or as straight as you can get it) without risk of being thrown off by the uneven fret tops, with the goal of your fretboard profile coming closer to matching your fret top profile
(and your point is well taken about there being sufficient "loading" on the truss rod for proper adjustability range in both directions)
As a very interested and very uninformed observer, this has to be one of the most insightful threads I've followed in a long time. I was actually walking around the house this morning wondering "does it matter if the neck is flat if the frets are flat?".
Thanks so much to the experts for their willingness to share and inform.
Thanks so much to the experts for their willingness to share and inform.
If you wander around thinking things like that.......Then you might become a Luthier! Be careful...
I'm hoping so. I've only got maybe 2 hours' work left on it. Just trimming, leveling and polishing the frets, exactly like I did on Mike's neck. Then put it back together.
But, maybe you've seen on my Secret Underground Lab thread, I'm deep in the middle of a major cleanup/rearrangement/consolidation of my shop. I'm spending long hours lifting boxes and moving shelving around. Unfortunately, it's important, and I have to do it now.
I'm going to try to get those few hours in on Alex's neck this weekend.
I have to start off by saying thank you Bruce.
I flew back home with my neck on thanksgiving day and put my bass back together. Since then I've been gigging 3 and 4 days a week, most of those using the bass back in rotation enjoying getting reacquainted putting it thru its paces. The neck plays amazing now! I have now achieved the lowest action I've ever been able to get, and the stainless frets added that last ounce of zing I was hoping to achieve. Success!
I flew back home with my neck on thanksgiving day and put my bass back together. Since then I've been gigging 3 and 4 days a week, most of those using the bass back in rotation enjoying getting reacquainted putting it thru its paces. The neck plays amazing now! I have now achieved the lowest action I've ever been able to get, and the stainless frets added that last ounce of zing I was hoping to achieve. Success!
Glad to hear it, Mike! It only had a small problem that was easily fixed. It should be good for many years of happy music now. A fine instrument.
I never tested them while the neck was here. Mike hasn't said anything since he got the neck back and in service, so I assume that they work.
They were never broken, nor did they get damaged during the refret.
