I've been boring holes with a .250" carbide endmill into stainless steel tubes (304). The wall thickness is roughly .035" I put a center drill hole there first to help keep from having 'caps' at the end of my tool when it goes to do the next hole. Either way, the end hole is a .257.

I'm using an endmill to help keep the inside of the from getting a lot of nasty chips. I'm putting 4-6 holes in each tube, depending on which part I'm doing. I'm running at 1800rpms and Feeding at 1ipm. My tools are going quickly, and end up building an aggressive set of chips fairly quickly. I've tried nearly doubling those speeds and feeds, which has less chips, but doesn't help my tool life at all.

*edit* changed to 1530rpms & 1.5ipm plunge, 3.0ipm on linear

Chips seem better, not sure about tool life yet

Any suggestions?

P.S.
I work in a very small shop, we have 2 Fadal 2016 VMCs. I am limited to end mills & drills, no fancy tooling. We have carbide, that's as fancy as we get.

Thanks in advance!