Official Luthiers Forum!

There's a whole lot of chatter on this topic, and I don't see much discussion of the mechanism of the body distortion that causes it. We all know that the neck moves around because of changes in the shape of the body, and we also know about seasonal saddle swaps related to that change.

So what changes? My musings suggest that the top picks up/releases moisture and the wood swells a bit (see comments about excess humidification and doming) and causes the sides to bow out a bit, the moisture swelling the wood across the plates, not along the plates, pulling the neck up. The expansion of the top and bottom are different, different wood species, so the expansion isn't even.

Do my notions make any sense?

Thanks!

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Peter Havriluk

I think the cause is string tension which over time deforms the body and allows the headblock to tilt inward. I don't think moisture has anything to do with it (or at least very little).

I think the need for a neck reset is the cumulative effect of a few changes in body shape. For example, in addition to changes in the back and sides allowing the neck block to tilt, there may be slowly increasing belly and the associated dip in front of the bridge that contributes to the worsening neck angle.

I’ve had guitars come through the shop for lifting bridges that appeared to also need a neck reset. Using belly-reduction techniques prior to regluing the bridge had the side effect of delaying the need for the neck reset for at least a while.

In the past several years Martin Guitars with well over a century of successful guitar manufacturing experience not to mention producing some of the standards that all others are judged against.... changed their view of neck resets.

So did we.

Neck resets for conventionally built steel string acoustic guitars as they are now and have been in the past are to be expected and really part of normal maintenance. Martin is no longer covering them as they did forever... under their excellent warranty unless there are visible defects in materials or workmanship meaning a gap at the heel for the most part.

Now with this said and a perhaps contrary opinion to most here where to us neck resets are to be expected in time the causes of neck reset time can be many but overall it is string tension over time.

We can get into material science and the different woods used in guitar construction but that would be an infinite slog in the subjective with no data so I will simply acknowledge that materials and their stiffness qualities certainly play a role. So does RH but not exactly why you may think, read on.

Increase the tension with 13's and raise the action such as for bluegrass where 5 - 7/64" is the Martin standard for action at the 12th and the neck wants to fold into the body faster. Decrease the string tension with 11's and low action for a finger style player neck reset time will still come but may come later.

A lifting bridge and the additional angle of the strings on the neck folding it into the body can contribute too which also makes a dry guitar likely a candidate for a neck reset faster than a properly humidified instrument.

We have also seen cut-a-way guitars with one model specifically needing neck resets in only several years and three of them did this so it's the design of the cut-away especially when the neck didn't just fold into the body it folded favoring one side, the non-cut-a-way side indicating that the neck joint was not ready for prime time.

So lots of reasons but overall it's always going to center around string tension, the design of the instrument and I'm suggesting here that expectations need to change too, a neck reset that you may see as "OMG that's going to be a nightmare to do" we see as a golden birthday for an instrument just nicely broken in and ready to be an even better friend for the rest of our days. . Reset the neck, dress the frets, new bone nut and saddle and the guitar will be BETTER than new.

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Ann Arbor Guitars

To add one thing to Hesh's post (from reading, not personal experience), my understanding is that most guitars reach an equilibrium where the body doesn't distort further and so no future neck resets are likely. Obviously some guitars which are more lightly built, or whose woods allow more distortion, keep moving, but most settle down. Do those with actual experience agree?

My 1931 Gibson tenor has never had a reset, but now ought to have one. The 12th fret action is 20-30% above the ideal and the saddle has little left for lowering it. I suspect it reached this stage years ago, but it's still playable all the way up (though not ideal from the 9th onwards). I've owned it for a couple of years, and nothing has changed in that time - I'll probably wait another year or two and monitor changes, delaying the reset until my playing regularly demands the higher frets.

Where did you read this? I’ve certainly seen guitars that have had multiple resets or have had one and are close to needing a second.

No I do not agree. "Most" guitars is a problematic word and makes this statement untrue. Some guitars may never need a neck reset true but when we are speaking of conventionally built steel string acoustic guitars most.... will need a neck reset and the only real question if the instrument remains in service and struggles to tension is when.

Where did you read this it's bull.

Tenors are a bit of a different animal but can need neck resets too.

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Ann Arbor Guitars

Yeah very true just because it was reset does not mean it won't need a second reset or even a third but with the water rising we may not care

Maybe builders here should consider new language in your warranties "for the working in the trade life of the luthier OR one neck reset which ever comes first?"

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Ann Arbor Guitars

I don't know if I ever read it somewhere or heard it but I always thought that a guitar becomes more stable over time and that say for example the first reset is required after ten years the second won't be after another ten but much more then that. Seems to make intuitive sense to me but I have no data.

One interesting thing I became aware of here or perhaps on another forum was of a neck reset technique where the guitar is held in traction so that the neck is pulled backwards in the reverse direction (opening the book) and the inside of the guitar is humidified and sealed off and it is left that way for like 6 weeks or something. I am not sure how time tested and proven that is but it is interesting. It woudl indicate that side deformation has a lot to do with the neck reset problem.

I've come across bowl-back mandolins from the early 1900s with the problem, where they remain unstable if they've gone too long under string tension with high action.

BTW, I'm logged in under my old nom de plume, waiting for Lance to re-activate my usual account after I changed my email address.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

Nice to see Burbank back Pat.

A very related topic is the new Martin SC series that was specifically engineered over a five years period I read to solve some of these need for a reset issues.

Even still with X braced backs and more reinforcement than other Martin models the neck is engineered to easily come off and have it's neck angle changed as need be. It's also engineered to counter the shortening of the scale length that happens when the neck starts wanting to visit it's old buddy the bridge meaning you can move the neck forward and aft too.

Or, in other words the latest engineering off the block from Martin accepts that neck angles deteriorate under string tension in time and the best remedy is making the thing serviceable...... Yep there's Hesh's favorite dang word again, serviceable....

So maybe Martin is saying that neck resets on conventionally (and now a reengineered model too) built steel string acoustic guitars is inevitable?

In my own mind I always return to where I started with Lutherie and that is that much of what came before us is pretty darn good and if you can get 30 years of service out of a D-35 and $2,200 investment before having to cough up a grand for a neck reset, fret dress, new bone nut, new bone saddle and maybe if necessary a warranty covered B string crack repair and pick guard replacement and when it's all done have a new D-35 that sounds like an old one, that may be real value too.

My family used to own a Steinway grand and that experience was not pay your $60K and enjoy it forever with no bills for servicing by any means..... The instrument needed to be religiously tuned, kept in 40 - 50 RH and serviced regularly which was not cheap by any means. Parts do wear out and some servicing exceeded the price of a neck reset.

My Honda had it's oil changed and tires rotated yesterday and GE, my old company will be here today to install the hose and clamp on my washer that broke after 3 years of service.

Point being.... stuff needs servicing and guitars are no different. You can attempt to build the need for service out of your instruments (good luck with that....) or you can join the long list of client advocates like me and instead make your stuff infinitely serviceable so that those who trusted us with their valuable coin are not disappointed in time and our names remain spoken without the addition of vulgarity....

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Ann Arbor Guitars

You may have seen it elsewhere but around 12 months ago there was a thread here about it, in the repair forum. I am skeptical about the longevity of it, or even if it works at all, but have no first hand data and may try it myself on a beater if I ever have the spare time.

I think side deformation does play a part in neck rotation. For me, it’s another good reason to use stiff linings.

Well Martin kind of backed themselves into a corner when they made wild claims that the dovetail neck joint has better tone then didn't they. Sure a dovetail joint is serviceable but at a price. I guess as long as they can continue to convince their customers that the price of a neck reset is worth the benefit in tone then they will continue on down that line. Tradition does have value though, this is true. And when done right a dovetail is a beautiful thing. But bolt on necks sure are easy to service.

The shop I just left (a Martin Warranty certified shop) used to figure a neck reset every 25-35 years. And the head luthier did them on a fairly regular basis. But I have to admit that resetting a Taylor was a heck of a lot easier...

My preference is a bolt on M&T joint for ease of adjustment and reset. And haven't had trouble convincing potential customers of the logic in that. But I've done a dovetail joint though rare.

Always wondered about bolt on dovetails as a compromise. Doesn't make a lot of sense to me but it would raise the serviceability quotient a bunch using a bolt instead of glue to lock the dovetail. Might satisfy those who buy the dovetail tone argument.

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Brian R, Wood Mechanic
N8ZED

good design & build quality are needed.
See many Taylors needing a neck reset?

Martins always get mentioned in neck resets.

Mike

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Mike Collins

Yes, I see a lot of Taylors needing neck resets, usually relatively early in their life compared to some other brands of guitar. So it’s great that it’s a minor upcharge to a setup to swap the shims out on a modern Taylor.

Taylor design and build quality are good but they have their flaws just like other manufacturers, as anyone who does bridge reglues will tell you

I’ve heard from someone high up in the Taylor service dept that they’ve recently finally taken steps to address their long standing issues with chronically lifting bridge wings.

Before we dropped Taylor and their warranty work we saw just as many Taylors needing a reset (considering) as Martins with the only difference being there are not as many Taylors 1) out in the wild and 2) there are also not as many Lemon Grove Taylors, the original and oldest ones as there are Martins of that vintage as well.

Additionally Taylors are typically not the ax of choice for the bluegrass, 13's with higher action crowd and this is the crowd who usually has neck reset time come sooner rather than later because of the added string tension and higher action.

We've never seen reason why a Taylor would not need to be reset as often as a Martin beyond the age of the instruments and tension they are subjected to.

I'm not a fan of Taylor Guitars and I'm speaking of the tone to be very specific. They are well built, innovative, good company, etc but just not my cup of THC.

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Ann Arbor Guitars

This is why we dropped them they saw lifting bridge wings as a much more minor repair than the whole nine yards that we will ONLY do to repair a lifting bridge with complete removal, clean-up, expansion of gluing area, perfecting fit and then exclusive use of fresh HHG. The alternative was the Taylor way with our name and reputation on the line and we would not go there and walked away.

We guarantee our work and repairs and that means that we use our methods that we know work and have worked for many years. Anyone who has a problem with this is cheerfully invited to go elsewhere and it's also never happened, yet.

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Ann Arbor Guitars

Hey Brian You made my day when you used the term "serviceability quotient" my favorite Loofery term aka SQ.

I agree a bolt-on dovetail would be interesting too and maybe one bolt under the extension too. A couple Allen wrenches, a padded hammer to tonk the heel with and the neck is off. That would be a huge improvement!

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Ann Arbor Guitars

You could perhaps design the bolt on dovetail joint so that tightening the bolt actually pushes the tail so it locks in place like it's supposed to. Otherwise it would make no sense to me.

String tension is the root cause, and that can't be avoided. What you CAN do when making or restoring a guitar is to make the top above and to the side of the soundhole very sturdy, that will at least delay the rotation of the neck into the soundhole.

A Martin style A-frame is great for this, it's amazing how much strength a small 6x6 mm spruce stick along the top grain gives. Making the X-braces and/or the brace above the soundhole big and strong is also a good thing. A fretboard on the thick side is good for the strength of the neck and body connection. Omitting a truss rod adjustable through the soundhole will also make the connection stronger (with a truss rod like that, there will typically have to be a hole in the brace under the fretboard, making it weaker).

The top above the soundhole don't contribute much to the tone anyway, it really doesn't make a big difference in tone, making that part of the top very stiff.

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New will change the old,
turn to ashes or gold

http://www.gammelgura.se

I agree a stronger structure above the sound hole is nice. But the load of the strings is felt not just in the top. The whole body deforms under string tension. It probably pays to stiffen the whole structure if the aim is to stop neck rotation.

A hole in a transverse brace for truss rod access can easily be omitted while still implementing a body-adjusting rod and many manufacturers do this.

But drilling a small hole for wrench access in a relatively tall brace doesn’t reduce its stiffness that much. Adding a small amount of height to the brace, or making it from a a stiffer material than the conventional softwood can compensate.

Right you are Josh body deformation is not just above the sound hole when we also have commonly bridge lifts and bellies and in the Martin world sunken tops in front of the bridge and the infamous B string crack next to the sound hole likely a function of pick guard shr*nkage... combined with string tension and too many wide cycles of uncontrolled RH.

So this is a forum of mostly builders so many here know how to beef things up and that's not the problem. The problem is we can build a tank that won't need a reset ever but it's not going to be a responsive instrument, light in weight, explosive in volume when someone digs in. So it's a tradeoff and the same is true for all stringed instruments really. Beefier in builds often goes hand in hand with acoustically inert... and less responsive.

Josh what I did on my production guitars that I built was to laminate a .020" CF layer into my upper transverse braces and then I drilled my truss rod access hole AND kept it just big enough for the wrench. We strongly disagree with manufacturers who make the truss rod difficult for anyone including a well informed owner to service their own instrument. So for Heshtone Guitars my serviceability quotient required me to make the truss rod accessible easily.

So the upper transverse braces are super stiff and won't move over time. I also used a massive neck block nearly twice the depth of a typical Martin. Dunno how my stuff will do over time with this configuration or if it will help at all. So far with some of them 15 - 17 years old I have not measured any movement in the neck angles.

But again I didn't set out to build a neck reset proof brick ****house instrument that you can stand on and paint your ceiling. I built guitars that I wanted to be ideally suited to be adult owned AND cared for.... high performance guitars that remain responsive as well as serviceable.

Anyhow there are countless approaches to attempting to belay the need for an eventual neck reset and I remain firmly in the camp that for everything there is a price... and the neck reset resistant acoustic steel string guitar should not sound like the paddle that they use in a parlor to scoop up the s from the oven.....

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Ann Arbor Guitars

You guys know about brick ****houses?!? I’ve always assumed that was one of our local colloquial terms over here