I use a little $30 Harbor Freight grinder to sharpen my chains. It works good, but technique is everything.
I set the stops on the grinder where it only dusts off the cutting edge of each tooth. Also, I file down the rakers the first time I sharpen the chain. In my opinion, the rakers are too high on the chains sold today. After taking a 16th of an inch off the rakers, the chain teeth take a deeper bite and results in a faster, cleaner cut.
