Drilling stainless steel

[macd]

The one thing I forgot to say was, use a centre punch first.

Bit tricky when you're enlarging an existing hole, as the OP is attempting to do. Air punch?

And, cf post #16, I suspect the OP has already had a go at the job and work-hardened the piece. That begs a different solution from the ones suggested.

 

[Kelpie]

Good point. He may need to use a step drill.

 

[KellysEye]

>What sort of oil should I use? Will engine oil do or do I have to buy something specially?

Machine oil 3-IN-ONE.