I used a tool and it took about 3 minutes. The second instrument was no better. I was milling mild steel at the correct speed and feed and a .010 cut. I threw the remaining 6 in the scrap heap. I think the Chinese still have a long way to go in tool making. I have used American made tools that I have resharpened myself and they did the job. In the future I will only buy American equipment. I don't mean to disparage Revain, it's none of their business, buyers beware. Why should I rate a tool if one star would be too high a rating? I think it would be to get to market.