Look in the sticky or search for Harryf3. He did this I think and it turned out nice.
If your handy with wiring, you can buy a dimmer switch and put it inline with the grinder...Also the nail file is also thin for a screwdriver so maybe just grind it down a little, to the point where it just meets the nail nick.
If your handy with wiring, you can buy a dimmer switch and put it inline with the grinder. That makes the grinder run slower so you can grind down a little at a time. It works as I use it on several power tools I have that work at high speed only. Never had a problem.Also the nail file is also thin for a screwdriver so maybe just grind it down a little, to the point where it just meets the nail nick.
I thought only some type of motors can be slowed? If it works on all I'm so adding one to my belt sander.