Making Softwood Pellets?

I am looking at picking up a small pellet mill and have access to free softwood dry sawdust, eastern white pine. I have several questions. Has anyone done this? Other then the sawdust, what else do I need? I keep reading other people's posts about using a binder.

I have one pelpro that works really well, and I'm thinking of adding a second one in an addition I am putting on. Thanks.