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I'm building a Grand concert with a redwood top (first time for redwood). I'm currently at 0.150" and it's starting to have a nice ring when I tap it. Using the Robbie O'Brian method of shaking it, there's still no sheet metal like wobble. I know I've got to go thinner, but I was wandering about where have you guys have been finding the sweet spot for redwood on small bodied guitars destined for light gauge strings?

Al I'm familiar with the method that you are using and know it from another Luthier besides Robbie but it's not what I do. Wasn't the shaking out a top technique a Kent Everett thing?

Every piece of wood is potentially different in terms of stiffness, even if it's from the very same tree... So I deflection test and over time you build up a bit of a database of what worked for you and what may not have worked as well as one would wish...

But since this question is asked often on forums and has been asked on the OLF too the answer that I like to offer that comes from my own personal experience and also recognizes that we can't have the piece of wood that you are using in our hands or know it's qualities is this:

Where with spruce I might use .115" as a base thickness irregardless of any testing and .130 - .135 for say western red cedar with redwood I find that the sweet spot for thickness tends to be in-between spruce and WRC generically speaking.

Remember too that irregardless of top thickness a guitar top is a "system" where other important components including bracing and just how stiff one braces a top as well are every bit as important as top thickness.

By the way my numbers above are for a dread*ught shaped/sized instrument. I go thinner for OM's, L-OO's and thinner yet if I was building an even smaller bodied guitar.

These days for me the top thickness is not all that important in the greater context of the top's "system" including bracing, bridge plate, bridge, etc. I want the top to be thick enough to have some structure but not so thin as the braces will telegraph through over time although some of the finest guitars that I have ever played had braces telegraphing through the top and very slightly visible from the outside.

But after all of this long-winded stuff from me you should be fine at around .125 give or take .005".

Lastly when I started this Lutherie madness I wanted to be the kind of Luthier that has what I call a feel for the wood. You know the folks who can flex a top in their hands and have a pretty good idea where to go from there.

With Redwood it can be uber stiff with the grain but across the grain as we are flexing with no warning split right in your hands.... So be careful with your flexing across the grain and you should be fine.

My only redwood top for CL caved in, but I wasn/t using humidity control ,it was dried for 15years

I'm using 50 yr old quarter sawn redwood from siding that was exposed to baking sun and zero-ish cold. Got enough for 3 guitars, could have got much more the rest went into the dumpster. The boss said take all you want.

Give it another try, and brace it in really low humidity this time. It's more brittle than spruce, but the dimensional change with humidity is less, so it can survive a larger increase. It's my favorite top wood, both for tone and for that ability to make nearly humidity-proof guitars.


Glad you saved some of it, but sad to hear that a lot was lost Breaks my heart that people squander such a precious and irreplaceable resource. Next time grab it all and send it to me

I think you'll get a lot of different and conflicting answers on how to decide top thickness The only method I know that can be precisely communicated via text is deflection testing, but I'm a touchy feely type.

I only flex along the grain on unbraced plates, since that's what's really resisting the string pull. And especially with quartersawn redwood, it's so stiff across the grain compared to its brittleness that it will split before you get a good sense of how stiff it is anyway.

I agree with Hesh that what's most important is the final stiffness of the plate and bracing as a system. Some builders swear by thick plates, and others have better success with thin. Just depends on the specific tone you prefer. IMO, thick top style works better on small guitars, and thin top style better on large guitars.

Is your GC shape like Taylor's 15" lower bout, or smaller? Either way, redwood is usually light and stiff enough that I'd say go thick top style. So thin it more by tap tone than flex. Stop when it has a nice solid, long sustaining ring to it (when cut to shape, hanging on your finger through the soundhole). Brace with the standard Martin pattern or whatever you like, and do final voicing by sanding the perimeter thinner from the outside after it's glued to the rim.

Thanks dennis, the top was not salvageable enough to be recycled . I do have another 15 redwood sets. But this time I will let the top sit in humidity between 40 45% for at least 5 days.Painful lesson learned. Redwood is vy splintery I had a fun routing the binding.

I just finished a 15" wide bouzouki with tonno basso redwood top. I got it down to .130 on the thickness sander. It felt a bit floppy but I used it anyway. If I had it to do over again I would have left it around .140". Still sounds good though not as much headroom as I would like.

I built my molds off of my Taylor 612. As for saving more...hindsight is 20/20.