We had a big storm blow through yesterday afternoon. Lotta wind and rain. We had a tree fall across our driveway,so when it finished raining I had some work to do. It was right at dark and as I was cutting I see sparks. Great! I had managed to cut through the tree into the gravel on the drive. Almost a brand new chain ruined. When I was looking to see if I had a replacement I found that I have 3 or 4 old chains that need a good sharpening. I have not had good success with a file. Can anyone recommend a good sharpener?