Building with red cedar

[seangil]

I'm going to do my first steel string build with red cedar this summer. So far, I have only used sitka spruce for tops. What adjustments do you make to your design in terms of top thickness, bracing, etc. when using red cedar rather than spruce? I expect that most people focus on the individual piece of wood in hand in making choices, but any rules of thumb that you use as a starting point?

[Mark Hatcher]

I find my cedar tops come in at about .010” thicker than Sitka on average.

[redir]

You are correct in that any piece of wood can have very different properties and so a luthier tends to build to each specific top. I have some red cedar that is the stiffest top wood in my entire collection which includes all kinds of spruce in different grades. In fact I have not built with it yet because I don't know how to handle it, it's so stiff.

Having said that as Mark mentioned it typically needs a bit more thickness then spruce.

I like the 'sheet metal' test. Thin out a top of any species of wood till when you can hold it mid way on it's long sides in the middle and shake, pump, it back and forth in front of you. If you hear that warble sound that you get when you shake a piece of sheet metal then stop thinning it out. I have compared that simple method to my deflection method and Trevor Gore's acoustic tap calculation method and it works amazingly well.

[John Arnold]

Because of the cube rule, a 10% change in thickness will alter the stiffness by 33%.

[printer2]

The denser the cedar the more you can treat it like spruce. I have some cedar fence boards that are heavy, hard and stiff. I was thinking of using it for the back and sides to make an all cedar guitar.