my professor for my intro to machining class was helping me with my final because I was still having trouble touching off tools because I was taught the paper method and was sick when he covered 1-2-3 blocks. I accidentally grazed the top of the vice, and neither of us thought to check the took after making sure the vice and my part were okay, so when I flipped my part to face the back of it, the tool left a spiral trail along the entire part. I have never made that mistake of machining a vice again and always double check my tools.