Cocobolo, Sinker Thicknessing Guidelines/ Suggestions...

[Texas Dave]

Hi, all,

I am currently building a Martin factory Jumbo (0000) kit- Indian Rosewood back and sides w/ spruce top.

I have decided, in the process, that I would like to make a gift of the finished guitar to a good friend.

This prompted me to make a second decision: namely, to replicate the process and build two guitars simultaneously: (the second guitar being for me.)

I have chosen different woods for the second guitar. After doing much reading and listening to sound files I settled on a pretty set of cocobolo back and sides and a beautiful sinker redwood top from RC Tonewoods and Sons.

I will be unable to thickness the wood myself, not having access to a thickness sander. I wish it were otherwise, this being such a crucial stage to the outcome of the guitar's voice, but that will have to be for the future.

So, I am going to need to send the wood off to LMI for thicknessing.

LMI normally sands their redwood tops to 0.115".

Are there any informed feelings out there for this being within good tonal response range for a redwood top? Has anyone worked with sinker redwood as a topwood who has feelings about this? Is this a conservative number? (In other words, is this too thick?) Is there a tighter parameter of tonewood responsiveness I can work within without being there to test the top as it is being thicknessed? Is there a better, less conservative bet that will not leave me with a flabby top?

As for the cocobolo, does anyone have any feelings regarding the back and side thicknesses? I called the Martin factory regarding their parameters for their rosewood backs and sides- their response was .065- .075" for the rosewood sides (LMI's standard for all sides is .090") and .105- .125" for their rosewood backs (LMI's standard is .095" for a joined back.)

Cocobolo's density allows for thinner dimensions than a less dense wood like Indian rosewood, and I have read a wide range of suggestions (.075 for cocobolo backs, .065 for cocobolo sides, for instance.)

It's all a crapshoot until I have more experience, but can someone give me some experienced numbers to work with? At this point I have thought to ask LMI to sand the cocobolo sides to .075", the back to .085", and the sinker redwood top to LMI's suggested 0.115".

Thanks Very Much

TD

P. S. Below are photos of the wood in question.

[hummingbird]

I would also like to know the answer to these questions.

I am planning a guitar with the same tonewoods.

[tippie53]

I use a deflection test to see how thin or think I need to be . In most cases backs can go to .105 tops .115 the sanding process will pull .005 more off . Sides can be as thin as .075

[Texas Dave]

Hi, Y'all,

I appreciate the responses (thanks for the compliment on the wood, Tony.)

Thanks to you, Tippie 53, for the guidelines. LMI has already joined the back, which I had thicknessed to .090". I arrived at this figure after some discourses with other luthiers who have done cocobolo/ sinker builds. Hope this will not be too extreme!

Your figures on the sides (.075") are right where I would have liked to take the sides down to, but LMI informed me that they could not take the sides down any thinner than .085", so of course that is what I settled on.

It is just developing that I may be able to gain access to a thickness sander here in Santa Cruz, Ca. If that's the case I will not only start by using the deflection test on the top (which I am joining myself) but perhaps I will be able to learn a little on top flexing/ testing in the process.

I will keep you all posted, and thanks again.

[bobcef]

Dave we could have thickness sanded for you. We offer that service at no charge to all our customers.

[Texas Dave]

Zowie! There's a lesson to come home to after a long day.

Well, I know where to get my wood thicknessed next time I buy from you guys.

Wonder how I missed that?