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Surprisingly enough- a 6 mm drill bit, or if you don't have one,1/4 drill bit will do.
A # 30 drill bit is 0.1285 inch, or fractionally more than a 1/8 bit.
Depends on the diameter of the conduit. Try for 1/4" larger diameter drill bit.
metal drill bit has a finer point
A titanium or cobalt drill bit.