At some point in the next week or two, I'll want to drill and tap a dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm diameter handrail, I'll have a 100-200mm offcut to practice on.
Now, we didn't do metalworking at school, so I'm lacking in the basics, but a bit of searching seems to suggest ...
For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need to check) hopefully an 18V cordless drill/driver isn't going to struggle?
Drill slowly to avoid work-hardening
Lubricate (use WD40 at a push)
As I'm tapping through, rather than into, the steel use a spiral point, rather than spiral flute, tap.
What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide coating etc) does the tap need to be to cope with 304 stainless?
I see 1/4" hex shank taps are available, e.g.
Will these work OK in the drill/driver? Or should I hand tap?
Given I'm unlikely to ever want/need a full tap/die set, can you buy screwdriver or T-handle style single taps?
Any other tips appreciated.