First and foremost make sure there are no tree limbs within 10' of the feeder in any direction. I had a raccoon that was using it's weight to make a branch drop down to within a couple of feet of the feeder and then free falling the rest of the way.
The pictures show the rest. A 2' section of 8" stove pipe with the upper end closed off with a 8" circle of wood or plywood and fit inside the pipe and fastened with screws. Drill a hole through the center of this that will fit a piece of 3/4 inch conduit long enough to get it to the height you want it above the ground. use a hose clamp on the conduit for the under side of the wood to rest on. Above that put the metal cone. Leave enough room for it to swivel on the support that comes with it. Makes it very difficult for anything to climb over it.
That takes care of the squirrels and raccoons, but the critter I had the most trouble with were the doves.
