I, too, use black locust for outdoor furniture projects. This bench has been sitting on my deck for at least 8 years now.




The legs are 2-1/2" x 2-1/2" IIRC, so the rough stock was at least 2-3/4 and more likely 3" thick. BL likes twist and warp quite a bit because the logs are almost never straight. The other various parts are a combination of thickness from 1/2", to 7/8", to 1-1/2".

I would mill enough pieces of the thickest stock you imagine using, adding 1/2" to accommodate warp, twist, etc. And I'd mill some at 5 or 6/4 for everything else.

Despite what many folks say, I found BL to be a pleasure to work with and not any tougher on tooling than other hardwoods.

Red mulberry makes fine outdoor furniture, too.

John