I had to cut some acute angles on 11-in, wide, 16-ft. long oak planks. Rather than haul them back to the shop to use the radial-arm saw, I devised the cutting fixture shown in the drawing. It’s basically a big version of the metal saw protractors I’d seen in mail-order catalogs, but the materials were practically free, and I didn’t have to wait for the mail carrier to bring it.
The 3/8-in. plywood base is 32 in. long. I made the distance from its right edge to the fence a little wider than the distance from the edge of my saw’s base to the blade. I used a fine-tooth blade to trim off the extra plywood with my circular saw, using the fence to guide the cut. That made the right edge of the base parallel with the fence. Cuts are aligned on this edge.
The circular portion of the plywood base has a 13-1/2-in. radius. A 1×2 fence that pivots on a machine screw is mounted under the fixture. I covered the edge of the pivoting fence that bears against the workpiece with a strip of sandpaper to keep the jig from slipping off its layout line. Once I’ve got the angle between the pivoting fence and saw-guide where I want it, I secure the fence to the base with a wingnut over a big washer.
Brad Schwartz, Santa Ana, CA