I agree with Les. My grinder is set up with a step pulley, and I run it at the slowest setting, but it still is pretty fast. Yesterday, I did some bevel grinding on a batch of knives and I ground out 7 of them with the same belt. These were not huge knives, but they were not tiny edc's either. At the end, the belt was noticably duller than a new one, but it still has a lot of life left in it. I still put it on my "new belt" hook. I dont use new belts for the initial bevel cut, I have an old one that I knock the edge off with. If I use a new one for that, I just get covered in a shower of orange dust and the belt loses a third of it's life. Other than that, they just keep going.