Luthiers (and wannabes): question about top thickness

[gitnoob]

I played an interesting guitar recently. Brand unspecified.

The top is Italian Spruce. Creamy white and *very* stiff -- stiffer than Adi. Body style is similar to a 12-fret 000.

The top thickness was a little bit over 0.1".

To me, this top feels *too* stiff. I have a funny feeling it'll never be broken in.

In your opinion, is 0.1" too thick for an Italian Spruce top? How long would you give it to "break in?"

[Larry Pattis]

Disclaimer: I am not a luthier, nor do I play one on TV.

I have noticed significant "breaking in" changes on guitars up to and beyond two years.

It's important to be into a guitar for the long run, when it comes to this kind of thing. I suspect many (if not most) folks would give up on an instrument long before a 2 year time frame.

It can be worth it.

On the other hand, it might not be worth it.

No one can tell you if it *will* be worth it, and not even (or especially) based on the top thickness of an instrument. The thickness (wherever you're measuring it) does not speak at all to it's strength-to-weight ratio, bracing, other possible thinning-of-the-top in other locations, etc...

[gitnoob]

I assume the top is not graduated in thickness, and I can't easily measure the bracing.

However, I just took some tap tones, and I was surprised that they peaked at a relateively low 190Hz.

I guess the top isn't as tight as I thought, but the sustain of the taps seemed very short and kind of "thudy." Hmm, time to experiment with new strings.

[tadol]

Definitely want luthier input on this - but from everything I've heard and read, the top thickness is just a variable, and cannot be isolated from the bracing pattern and size, and the bridge. All of those work together very closely to create a vibrating surface. Also, as I understand it, most tops are varying in thickness from center to edge.

So it may be too thick, may be too thin, or it may be just right - Does that help?



Hood, Table for one - Red, your table is ready -

[Brock Poling]

It really depends. The way *I* do it is to thickness to deflection. So in a given system I deflect a top to a projected deflection and that is the final thickness. I don't sand to a dimension.

Wood has different stiffness properties and the goal is to get to a known longitudinal stiffness. That may be .1 or .07. It is hard to know ahead of time.

If the guitar sounds good I wouldn't give it a second thought.

[Matt Mustapick]

Originally Posted by gitnoob

In your opinion, is 0.1" too thick for an Italian Spruce top?

In general (and please note that you cannot go from the general to the specific, as your question would lead to), 0.1" is certainly not thick for most recipes. But of course it depends a whole lot on a particular piece of wood and the bracing that's on it, so that changes everything. Is 14 ounces too much to drink? Probably not if it's water or beer, but if it's tequilla...

Originally Posted by gitnoob

How long would you give it to "break in?"

Zero days.

[alohachris]

Aloha,

In my experience, how long it takes to break in a guitar depends ENTIRELY on the player, how often he uses the axe, and the styles he plays.

I mean, the guys with all the "Quivers" here who are constantly turning over guitars will never get the full benefit out of ANY guitar because they just don't put the time in. Has nothing to do with top thickness.

alohachris

[Howard Klepper]

I don't know how you could tell that a top that is on a finished guitar is "stiffer than Adi." Which piece of "Adi"? How can you know this when it is braced and on a guitar?

And how much is "a little bit over" with reference to 0.1"? We don't work in 10ths of an inch--usually we work in 1000ths.

It is very unlikely that an Italian spruce top at 0.100" is too thick. Since you have chosen not to reveal anything else about the guitar, the question about top thickness and break in is not highly answerable. But .100" is rather thin for most builders' styles of construction. It may be thick for some builder's style.

[gitnoob]

Originally Posted by Howard Klepper

I don't know how you could tell that a top that is on a finished guitar is "stiffer than Adi." Which piece of "Adi"? How can you know this when it is braced and on a guitar?

And how much is "a little bit over" with reference to 0.1"? We don't work in 10ths of an inch--usually we work in 1000ths.

It is very unlikely that an Italian spruce top at 0.100" is too thick. Since you have chosen not to reveal anything else about the guitar, the question about top thickness and break in is not highly answerable. But .100" is rather thin for most builders' styles of construction. It may be thick for some builder's style.

Yes, I realize the information is pretty vague, but I was just looking for a "feel" given that Italian Spruce is generally listed at the stiff-end of the top-wood stiffness spectrum.

And my calipers read 0.105" or so, but I was measuring near the sound hole, and I don't have a high degree of confidence in that measurement.

Basically, my logic went like this:

I love the specs, but I'm not crazy about the sound. It sounds tight and bright, which is not normally what I'd expect from a 12-fret 000.

So I grabbed the only metrics I had: wood species and top thickness (and then tap tone), hoping they would provide insight into what's going on.

In my *very* limited experience, 0.1" seems reasonable for Sitka, so I figured Italian Spruce might warrant something less thick.

If it was obviously too thick, then I would stop hoping for tonal improvement.

But if the thickness is within the "normal" range, then I'll keep experimenting with strings and other parameters I can control.

[Howard Klepper]

You left out the "metric" that would have been most informative: the builder.

[airguitarro]

Also, would there also be another variable in that the thickness would differ where did you measured the thickness of the top? I recall reading that the soundhole is not a good place to do that since there may be a layer of wood to strengthen the guitar there. So if you measured the thickness there, that may not reliably tell you the true thickness of the top in the important places that do matter more.

[PWoolson]

There are a couple of terms that you use that make me take pause.

"a bit over 0.1""
and
"0.105" or so"
As Howard mentioned, we measure in thousandths and don't use terms like "a bit over" or "or so" when measuring. If indeed this top is .105", I'd say that is nowhere near too thick.
Also, you mentioned that it is too stiff. How are you measuring that stiffness when it's built into a guitar? I can't think of a way that one could flex a top when it's all built up.

[Brackett Instruments]

It depends on the individual top, the bracing, and the string tension. I doubt you find a factory guitar with a top that thin. Most of my tops are thinner, but liek Brock, I thickness my tops by deflection, not some pre determined dimension.

[Tim McKnight]

I too thickness my tops to a given deflection which equates to a longitudinal stiffness. I have built guitars with .065" - .145" all with the same stiffness even though there was a wide range of thicknesses. That just shows you how much inherent variation exists in tops. Martin uses .110" - .120" as a statndard thickness for their tops on every guitar that rolls off the line. There are lots of ways to approach this topic but none will tell you how long it will take for the guitar to break in. A ToneRite will help to speed the process on any guitar so that is another option.

[JohnJayPl]

Originally Posted by Tim McKnight

I too thickness my tops to a given deflection which equates to a longitudinal stiffness. I have built guitars with .065" - .145" all with the same stiffness even though there was a wide range of thicknesses. That just shows you how much inherent variation exists in tops. Martin uses .110" - .120" as a statndard thickness for their tops on every guitar that rolls off the line. There are lots of ways to approach this topic but none will tell you how long it will take for the guitar to break in. A ToneRite will help to speed the process on any guitar so that is another option.

Why do you thickness the tops to a given deflection?

What other calibrations does the top get along the way?

Just curious,

John