I got one of those chain sharpeners from Northern Tool, I think it was. I have pretty much figured out how to use it, but I don't think I'm getting the best results I could be. It seems the chains could stay sharp for longer than they do. One of the biggest issues I see happening is that no matter how I do it, the thing burns the tips of the cutters. Fast pass, slow pass, very shallow cut, etc., nothing seems to change that. So what, are you supposed to spay some sort of coolant on it?