I am trying to drill though a stainless 3/8" steel bolt (grade 6) on a pool pump. How long should it take to go 1/2 inch? I think after an hour, I managed to get through 1/8 inch using oil as a lubricant. I am using a 1/4 Dewalt Cobolt bit from Lowls (listed for stainless steel). Is this better than the Irwin titanium bits? I have some diamond bits from Harbor Freight tools, but it seems as if the diamond dust was scraped off very quickly..
Any suggestions on what else to do, i.e. take it to a mechanic who will charge $50 an hour. Are there any suggested drill bits made from industrial diamonds or are they overpriced?