Diamond Grinding Wheel Dresser
Even if you only use your grinder occasionally or for casual jobs, it's a really good idea to "dress" the wheel from time to time. This little tool has a row of industrial diamonds set in the cross piece, and it does a dandy job of truing up the wheel so it cuts better and doesn't bounce your work all over the place. The multi stone dresser may be a bit pricey, but single stone versions do a good job too, and they are remarkably inexpensive.