See I didn t forget that I was going to demo the layout of some different polygons with a compass. The reason Im behind schedule is because I couldn t find my compass here at home and had to wait and get my other one from work. Now, I know this originated from a discussion on laying out an octagon, however, I have decided to start with a hexagon since it is the easiest to layout.
Step two is with your compass set at the radius of the circle strike 6 arc around the circumference of the circle, using the point were the arc and circumference of the circle meets as your starting point for each arc. You create your first arc by just placing the pointer of the compass on the circumference of the circle and then strike your first arc. after this work your way around the circle from arc to arc. If your not real percise about this layout it may take more than one try to make it turn out right. The pointer of the compass needs to be right on the intersection between the two or else by the time you get around to the last arc, your going to either be long or short in your layout. Your 6th arc needs to fall right on the spot were you had the pointed end of the compass contact the circumference of the circle when you struck your very first arc.
Now this layout can be used for more the just creating a hexagon. It can also be used for laying out the location of 6 evenly spaced holes. Plus too, if you cancel out every other arc, after you have layed out all six first, you end up with 3 evenly spaced location around the circle these could be used to layout holes too, but most times I use this 3 equal spacing layout for locating the position of the legs when Im building a table or stand that uses pipe or tube for the vertical column, and the plan calls for only 3 support legs. I do this by laying out the circumference of the pipe, with my compass, onto a peice of paper. Then I layout the six locations. then I cancel out every other arc. Then I transfer the location of the 3 arcs left to the end of the pipe or tube.
Dan, I first used this to layout three equidistant points on a 1961 Ford Falcon harmonic balancer pulley. Valve adjustment called for rotating crank 120 degrees at a time, but Ford in their infinate wisdom did not mark pulley except for TDC.