I was struggling with cutting holes in stainless steel sheet and barrels until I bought this set, works better than I could imagine. I've only used it in a drill press but cut about 20 holes with a 2" bit and it continues to form well. I use the slowest speed, some wonderful mystery cutting oil and lots of down pressure. end of the cut. I think my technique needs improvement. This is an amazing set of hole saws. Pro - Hole Saw is a flat cutter, ideal for electrical enclosures, Minus - Hole Saw is a flat cutter, not ideal for cutting into pipe sidewalls or pipe notches.