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I came across some straight grain quarter sawn (about 80 to 90 degree) Douglas fir today. They are 1.5" squares about 4 ft long each.
There are about 16 lines per inch.
I'm thinking I can use this for braces. These are older stock for sure. A small knot in 2 or 3 places that can be cut out.

I've read that doug fir is heavier than spruce by about 15% but stiffer and stronger.

I could do 3 or 4 guitars with these,

What do you all think? The braces could probably be narrower possibly not as tall as spruce would need to be.

I just cut some of the fir and compared it to Sitka spruce.

Results with what spruce I have left.

Sitka spruce: 3/4" x 3/8" x 20" = 44.5 grams

Douglas Fir: 5/8" x 3/8" x 20" (2 pieces) one at 44.5 gr and one at 42.5 gr.

The reason the fir is cut at 5/8" tall is I cut a 1 3/8" strip in half.

Now I cut a fir strip that matches the spruce in size and the weight on this one is 48.0 gr.

So the fir comes out 3.5 grams heavier. That's not bad. If I use the fir at 5/16" wide I'm betting it will be darn close to the spruce in weight, and it will be more stiff.

Percentage is fir is about 8% heavier.

I think I will use it on the next guitar and see how it works.

I have enough for at least 4 guitars 😁

It will be awhile before the next one gets started.

Kevin, Douglas-fir (correctly spelled with a hyphen, since it is not a true fir, closer to hemlock) is very stiff and there is lots online about using it for bracewood. One interesting discussion here, including Douglass Scott, a very successful classical builder who lives in the same town as I do (though I have not met him):

https://www.classicalguitardelcamp.com/ ... hp?t=97471

Some of the discussion is over my head but I think you are figuring some of this stuff out yourself. I would not hesitate to try it; I have a couple of D-fir tops in waiting. And Dean Derby, on this forum, has made some guitars entirely of D-fir (not sure of bracing) and may contribute here. Bruce W.

Bruce
Excellent info and commentary on the fir.

I am going to use it on the next guitar which will probably be a Mayan Walnut OM with a redwood top. And Fir braces! We'll call it an experiment.

Most of the 'sacred' woods we use were once put to use because they (1) worked just fine and (2) were cheap. If I had some good-looking Douglas fir I'd use it in a heartbeat.

Anybody who repairs guitars well knows the junk factories bury inside their guitars, and you're way, way, ahead of that game.