We make sliding bevels here at Crucible Tool, and we love them. But you don’t need them for making chairs.
Once when I couldn’t find my sliding bevel, I made some blocks of wood with fixed angles sawn on the ends. These guided my drill bit while making mortises. A few years later, I saw an improvement on the idea in a photo of someone’s shop (I cannot remember where). These doo-dads (shown above) were in the background – I don’t think they were even discussed in the article. But they are brilliant.
It’s basically a piece of wood (3/4” x 1-1/2” x 5” or so) with a groove plowed down the middle. The groove is the same width as the thickness of hardboard (usually 1/8” thick). Then you cut the desired angles onto the ends of bits of hardboard and slide them into the grooves.
The wooden base keeps the tool stable. The removable hardboard means you can swap out angles for different chairs. The two stationary bevels shown in the photo above do all the leg angles for the staked armchair in “The Anarchist’s Design Book” plus about half the chairs in “The Stick Chair Book.”
The nice thing about these stationary bevels is they don’t lose their setting when you drop them off the bench.
— Christopher Schwarz