On 07/13/2015 11:36 AM, Terry Coombs wrote:
philo wrote:
On 07/13/2015 03:02 AM, Deodiaus wrote:
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?



Sheesh


Do not start out at the full size, use a smaller bit first...
maybe 1/8" or even smaller

For a quarter inch hole ? I 've never had a problem unless I let the bit
rub and work-harden the SS . Heavy pressure and a low speed are key .




Yes...as he said it was stainless steel...otherwise a pilot hole would
probably not be needed.