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Post by Auf Kiltre on May 16, 2021 13:16:35 GMT -5
I've never experienced/diagnosed this before and am not sure what I'm looking at. I just did a fret level/crown on one of my necks and it turned out fairly well with some exceptions. Here are the specs; Warmoth 10-16 radius, 6105 fret wire. I'm noticing some rattle on the low E and A strings. When sighting down the neck (both directions) I think I perceive a very slight tilt toward the treble side, particularly toward the nut. When I set my relief I notice a drift from the bass side to the treble side (capo 1st fret, depress last fret, measure @ 8th fret; I see a small increase in gap toward high E). This drift isn't confined to just the 8th fret.
When I prepped the neck for leveling I did my usual approach. Using a notched straight edge from SM eyeballed first the fretboard, then the frets. Lastly I sharpie'd the frets and using my sanding beam slightly scratched back and forth to see if I was getting the middle of the fretboard. Once I felt comfortable I had the board straight I leveled, crowned and checked with a fret rocker. All looked well. I do now notice a very small rocking around the 11th/12th fret.
I don't know if the compound radius factors in. I've done one other leveling/crowning on a 10-16 board with no ill side effects. Bottom line is that this guitar is playable and actually probably better than a few other of my guitars. I'm just curious what the approach may be to diagnose a twist that isn't real blatant.
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Post by funkykikuchiyo on May 16, 2021 13:51:09 GMT -5
The quickest way to diagnose a twist is to check relief on both the bass and treble sides and see if there is a difference. In extreme cases, one will be too far forward bowed while the other is back bowed. Realistically, pretty much every neck has some degree of twist to it, it is just a matter of whether it is enough to be a nuisance, and if you're lucky the treble side is the straighter side and the bass side the more bowed side as that plays well into the setup.
If you used a long block when leveling, the block should have shown a twist where you were sanding more the middle frets on one side and more the ends on the other.
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Wrnchbndr
Wholenote
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Formerly Known As: WRNCHBNDR
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Post by Wrnchbndr on May 16, 2021 16:55:25 GMT -5
Terms of twisted and warped can be misleading to the imagination. It’s possible to have a fair twist with no ill effect if its just a matter of the nut being offset from the general level of the top of the guitar or the end of the fretboard. Differences of relief between the treble side and the bass side becomes a major issue if the treble side is the one with more relief. The opposite is much more forgiving and I think Funcky is saying the same thing. For me, slotted straight edges are inappropriate when discussing relief or rather,.. I simply have never seen a need for them. All that matters is the relationship and level of the fret crowns. With your compound radius neck, relief measurements and evaluations need to be along the six string lies. Optimally, you should be able to adjust the truss rod to achieve a fret crown level down the very center of the neck and not observe any teetering on either the bass or the treble side. You need to be careful to not create false evaluations from the weight of your hands when checking things like this. Once you get your neck flat, you can take a .001 feeler gauge and see if you have any low spots. All this takes a delicate touch. My process has always involved the neck being supported by a neck support near the headstock and utilizing the weight of the guitar to put a slight amount of forward force against the neck but the real intent is to keep things consistent and always be aware that the weight of your hand and tools can influence the evaluation. Adjust the neck to be flat down the centerline and then see what is going on in the string lies.
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Post by Auf Kiltre on May 16, 2021 20:38:11 GMT -5
Thanks for the insights, it's great to have input from the truly skilled.
I think there is some minor hinkiness here and marginal quality of work on my part, but the end result is passable. I tightened up the trussrod a bit more using the center strings as my guide and have playable action that is lower than I'll probably keep it.
Is it possible that trussrod adjustment can cause more than concave/convex movement, as in slight improvement top to bottom?
Either way, all is good.
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Post by funkykikuchiyo on May 16, 2021 20:55:47 GMT -5
Possible... but not really likely. Truss rods sometimes will turn the neck as it bows, sometimes because a neck is significantly more stiff on one side (usually with multi-piece necks) and they can be weird if they're not installed dead center - occasionally happens with dramatically asymetrical peghead designs. It is for this (and this only) that dressing frets under tension could possibly be useful, like with a plek or that weird giant jig Stew Mac used to sell. I don't see either of those things playing out with a Warmoth neck.
Sometimes there are optic illusions at play. I run into it more with acoustics - where the truss rod is actually affecting the neck the most can shift, and sometimes a bowed neck on an acoustic can look straight until you straighten it and you realize it was bowed the whole time and you were interpreting the bow as a neck angle issue. If a neck is giving me guff and I'm not sure what's going on, I'll err on the side of straightening it, possibly cut my nut and saddle with it overly straight intentionally, and slowly loosen it until it finds its good resting spot. This has worked well for me because A) it is a "cut on the waste side of the line" kind of thing for nuts and saddles that adjust by being sanded, and B) when our eyes/muscle memory guess wrong on neck relief, it almost always guesses with too much relief. Most common with beginners, but it can sneak up on any of us.
Another thing on the optic illusions, I've had necks that I could've sworn would be twisted, S curve and a whole bunch of other problems, but once they are straightened they look fine.
Yet another thing that could happen, if the fingerboard had some fall away then doing the string straight edge thing at the edge of the fingerboard might make it seem straighter than it is, because it is going to rest firmly on a bunch of frets before creating that friendly relief gap. Warmoth does final fingerboard sanding with a random orbital to give it that polish and that can sometimes make for some weird geometry. You might have just run into something like that.
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Post by funkykikuchiyo on May 16, 2021 21:00:19 GMT -5
Oh, and to wrnch's point about the notched straight edge... I generally agree, but didn't say anything on the idea "if it works for you, go for it". The fret tops matter more than the space between the frets. Think if you scalloped each fret to a different depth, you'd never get the notched straight edge to work right, but you'd still have a straight neck.
Back to the optic illusions, given that about the notched straight edges, given the compound radius, and given what we know about the orbital sanding of the fingerboard, it is possible you had some false data at that step.
FWIW, when I straighten out before long block sanding of frets/fingerboard, I first go by eye, and then I watch the scratches where the block is first making contact with my first few passes, checking both the bass and treble side, and I usually make very, very small adjustments at that point to bring it in where I want it. Nothing saying this is how anyone else should do it, but it seems to work okay for me.
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Post by Auf Kiltre on May 16, 2021 21:08:08 GMT -5
Yep yep, just to clarify, I don't rely on the notched straight edge touching the fretboard, but shifted over and riding on top of the frets. I'll look to see if there is a difference between the two, but always rely on the frets to tell the story.
I too make short scrubs with the sanding beam to see where the gaps may be, then make small adjustments.
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Wrnchbndr
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Post by Wrnchbndr on May 16, 2021 22:22:08 GMT -5
I’m totally in agreement with the potential for an optical illusion. I worked for a music store owner who would sight down a neck and either proclaim that the neck was perfect or the guitar needed a truss rod adjustment. He was wrong a lot more often than he was right and I’m still surprised that a guy could operate a music store for so many years and still not have a clue about basic guitar dynamics. Some optical inspections can yield obvious problems but there is nothing better than a precision straight edge to illuminate facts that permit intelligent decisions.
I lay a straight edge down the center of the neck and adjust the truss rod to achieve fret contact on #1 and the last fret that occurs prior to the intersection of the body. This way it includes the process for acoustics and arch tops which often have a “fall off” I do a check to see that if I tighten the truss rod in the slightest, the straightedge will find a pivot point some place in the middle - its a twisting motion of sorts more than utilizing the straightedge as a fret rocker - you’re looking for the happy place. It comes down to developing a feel while being disciplined to not push down on the neck. Once you get to this truss rod adjustment place, you can do all sorts of intelligent evaluation looking for pivoting in other string lies and even passing a .001” feeler gauge along the fret crowns searching for valleys. This is important because one single fret that is elevated, maybe a fret that isn’t properly seated, can totally undermine your process. It’s all about developing a rational progressive process to achieve a level neck — a level field of fret crowns.
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