by Steve Martin » Tue Feb 27, 2018 4:54 am
One way to make a tool to taper the leg holes is to buy a saw, under several different names but the blade tapers from the tip to the handle, sometimes called a hole saw, about 8"-12" long with a removable handle. Find a relatively hard wood, hard maple, oak, ash, etc. about 6" longer than the blade and large enough in profile to turn a tapering cylinder, so that the cylinder is smaller than the width of the blade, by about the depth of the teeth or slightly less. Sawing a slot through the middle of the wood, wide enough for the blade to slide into the slit but won't be sloppy, usually while rectilinear, for more safely cutting the slot. Then turn the cylinder so that the teeth of the blade will just emerge from the cylinder, when slid into the slit. Prior to turning, drill a 1/2" or so hole across the "handle" area (perpendicular) into which you can place a shaft to turn the auger when completed. After several trials, I used a chisel to cut a 1/4" bevel on each side of the slit, on both sides of the cylinder, allowing the waste to move away from the teeth as the auger is cutting. I also sharpen the opposite side of the blade from the teeth in the manner I sharpen scrapers, to help clean up the surface of the tapered hole. I believe I first read about this in a reference to Jennie Alexander's first book on making a chair or, possibly in a Drew Lagsners blog or other writing.
Trust this is not too obtuse. I now have two of these for varying size leg diameters. They work great!