also check which kind of bit you are using...the arbour sanding bands create the most heat out of them all.Next best is the diamond bit, and actually you can get a lubricating oil to apply to the nail before you use those to reduce heat. ALong with that make sure to check you speed and pressure....if your speed is too low you will tend to apply more pressure. a slightly higher speed and less pressure along with making sure not to file in one spot too long will bit you better success, but definately look into a e-file training class...they are most informative, and you will learn some great techniques to cut down your e-filing time.