Douglas Fir for bracing wood?

[Kevin Sjostrand]

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.

[Kevin Sjostrand]

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.

[Stray Feathers]

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.

[Kevin Sjostrand]

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.

[phavriluk]

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.