Just saw this show for the first time and a guy is cutting stone top with a 4in grinder and a Dimond blade, not wearing glasses bad bad bad idea. I've worked with Dimond blades for 40 years and have seen them break not mention concrete stone and metal debris flying out. Also no guard on the grinder ,no reason to remove the guard when it doesn't interfere with the cutting being done. If using fiber blades and wire wheels a face shield is best. And fiber blades can blow apart especially if they have gotten wet. Be careful life is hard enough with two eyes