The trickiest cut when building a chair or stool is leveling the feet. This cut is always a wacky compound angle. And when you combine a compound angle with a foot that is an odd shape, such as the octagon shown here, it can be difficult to keep your saw in the right plane.
Here’s how I do it – it’s a method that has yet to fail me.
Lay out the cut you want to make on all the facets of the leg. I use a mechanical pencil so the line is a consistent width and easy to see.
Making this cut is a lot like drawing a line in the sand at the beach. If you draw a shallow ditch in the sand with your finger, the ocean will follow that ditch because it is the path of least resistance.
So think of your saw as water.
Make a shallow kerf (about 1/16” deep is fine) on all the leg’s facets or surfaces that you can see. Don’t worry about the surfaces you can’t see because they face the floor. Try to make these kerf so they are all in the same plane (that plane will eventually represent the floor that your chair’s feet will rest upon). But if your angle is off a bit, don’t worry.
Now you can deepen these kerfs slightly. Hold the saw at the correct angle for the cut and saw down, joining the kerfs on two facets. When your sawblade reaches the corners of both facets, stop sawing. Move the saw to join the kerf you already made with the shallow kerf on an adjacent facet.
Ues the deeper facet to guide the saw as you join these two facets. Again, stop sawing when you reach the corner of the next adjacent facet. Continue this process until you have joined all the facets you can see.
Now it’s time to trust your layout and your kerfs. Start sawing down to finish the cut. The kerfs all around the leg will guide the saw – they are the path of least resistance. As long as you don’t try to steer the saw, it will follow the kerfs.
— Christopher Schwarz