Octagon
After making the 22.5 degree jig I came up with a cheat.
Make the octagon in 2 halves each one being a 4 sided piece.
Dry fit the 2 sections together, if they match exactly give yourself a pat on the back .............
If they dont match exactly, then prior to gluing them together you can run both of the 4 sided sections along some sandpaper glued to a flat piece of wood or glass, ensuring that the angle between the first edge and the 4th edge of the octagon is exactly 180 degrees.
This helps to eliminate the accumulated inaccuracies from the multiple cuts.
This will work with any 4 6 8 10 12 (etc) sided figure, as when you are half way around the polygon the first and last edges should be in the same plane.
Regards
Bill
I made an octagonal "pipe" once just for fun
After making the 22.5 degree jig I came up with a cheat.
Make the octagon in 2 halves each one being a 4 sided piece.
Dry fit the 2 sections together, if they match exactly give yourself a pat on the back .............
If they dont match exactly, then prior to gluing them together you can run both of the 4 sided sections along some sandpaper glued to a flat piece of wood or glass, ensuring that the angle between the first edge and the 4th edge of the octagon is exactly 180 degrees.
This helps to eliminate the accumulated inaccuracies from the multiple cuts.
This will work with any 4 6 8 10 12 (etc) sided figure, as when you are half way around the polygon the first and last edges should be in the same plane.
Regards
Bill