I have a few general questions about machining 304 stainless tube on a manual knee mill. I'm going to be using 2 diffrent cutters and was wondering if I was supposed to use a cutting oil or not? I haven't machined much stainless and I recall reading past statements that you were not supposed to use cutting oil on stainless, is that true or not?

The first tool is a "Roughing Ticn-coat Cobalt Fine Pitch End Mill, 7/8" Mill Dia" and the second is a "Hi-performance Carbide End Mill For Stainless, 3 Flute Rounded Edge, 1/4" Mill Dia". The tube is .875 OD, .745 ID and .065 wall.

What RPM should I run the 7/8 and 1/4" end mills at? The 7/8" EM will be a side cut into the end of the tube, and the 1/4" EM will be used to cut a small "window" into the side wall.

I hope I supplied enough info to help answer the question, if not LMK, thanks.

Pretty much any grade carbide will work for what your doing. Your limiting factor is going to be fixturing. I did something similar and I put the tube in a table vice and placed a piece of drill rod inside and clamped that down tight. The bench vice only located the tube, the drill rod clamped it down for machining. I think I ran a 1/4" carbide EM 900rpm, plunge at 2ipm and feed at 5ipm to put a 7/8" hole in a 2.5" tube, but the hole was offset so milling was the most practical way.

Shouldn't be too dificult as long as you can hold the tube without pinching or distorting it.

MC