When we decided to put up a bird feeder we designed it to be far away from any branch and high enough off the ground. We hoped that this would be enough to keep the Squirrels at bay. We also designed it as a pulley-cable-hook system with a very thin cable hoping it wouldn't give them enough of a foot hold. But they are smart creatures and up for the challenge.
As soon as the bird feeder went up, the Squirrels were all over it. Within a few hours, they had mastered the subtle trick of getting on to the feeder. They seemed to have taken some cliff hanging lessons from Sly Stallone.
Our first step was to mix in some cayenne powder with the seeds. This didn't seem to bother them one bit. In fact they seem to enjoy the added spice and kick and were coming back for more. We then installed a squirrel baffle that we rigged using a cheap metal salad tray that was picked up from Smart-n-Final.
That has seemed to do the trick for the last few days enough to "baffle" them. But the Squirrels are content eating the scraps the birds drop as they feed.