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I have some nicely quartered, fine grained redwood that is 60-70 years old laying around my shop just waiting for a guitar. I was thinking mabe a concert style body set up for nylon strings. Not a true classical, but still a small bodied guitar.
I've never used redwood so I was hoping to get some insight on where to start on thickness. Do I go thicker, or thinner than Sitka?

Thanks,
Al

Generally should be thicker. There's a lot of variety in redwood, due to the size and age of the trees. Seems to span the range between cedar and spruce. For starters, measure the density of your board. But for me, the final thickness is determined by flexing it with my fingers.

Best soundboard wood there is, IMO

That's exactly where deflection testing comes in real handy....

Thanks for the info.

Al

If.... you have not built a database containing your records of various top thicknesses for guitars that you have built AND if you have not done deflection testing to populate your database AND if you don't feel like you have developed a "feel" for top stiffness a safe bet is this: Spruce tops thinnest, Redwood in the middle and WRC thickest.

More specifically if you simply want a likely safe number factoring in body size too if you were to go with say .105 with decent spruce and perhaps .125 with WRC redwood would be a middle number such as say .115.

Some stuff to know. Redwood can be a bit deceptive in that although it can have great stiffness along the grain and even exhibit not too bad stiffness across the grain it can also snap when flexing with virtually no warning. Or when it goes it goes quickly and unexpectedly when flexing. I personally found Redwood to be difficult for at least me to get the hand flexing down.

So back to that number - try .115 to .120 for this body size and if you would like to be a bit more conservative try .120 - .125".

Tonally... Redwood is a great wood IMHO. Although subjective as hell my impressions are that Redwood can have strong fundamentals and lush overtones reminding me a bit of Adi but without as much projection and requiring a bit more to drive it. I think that it would be fine with nylon strings too.

Hope this helps.

Hesh is not kidding about redwood's tendency to snap. It can be very brittle. I've found that I have to be particularly careful trimming overhangs, cutting and sanding sound holes, etc., because it throws chips very easily. But it's pretty and makes a nice sounding instrument and it's worth all the effort for at least one instrument--or lots of instruments if these wood properties don't bother you. Good luck on your guitar!
Patrick