Just for the experience, I tried cutting a 0.625" diameter brass rod off with a BXA-7 cutoff tool, both dry and wet, even though all the books say that brass is best cut dry.
Dry, it squealed loudly but cut nicely at ~800 rpm, yielding random piles of little brass needles as long as the cutoff blade was wide.
Wet with oil emulsion (Rustlick WS-5050), it squealed very quietly at the same speed, but yielded mirror surfaces. The wet piles of little brass needles sitting on the top of the cutoff blade were not random, instead looking like stacked firewood, and the needles ended up in neat piles rather than going everywhere.
A better lubricant might eliminate the brass squeal entirely. Steel cut off in the same setup does not squeal at all.
So, cutting brass wet actually helps, at least with an oil emulsion. This ties in with the historical use of whole milk as a cutting fluid for brass and copper, milk being an emulsion of butterfat in water.
At least WS-5050 doesn't turn rancid.
Joe Gwinn