I saw the HackAday video of a guy shaping limestone with a screwdriver today. I also went and saw the YouTube video of CNC milling limestone. They were using a flood system with their mill.
So, as a total newbie -- why flood limestone? It seems really soft. What would happen if you milled it without the liquid? What if you went shallow and slow, with cooling breaks for the tool -- would that work?
The flood coolant has several functions. It carries away the loose material dislodged by the cutting process, so it doesn't clog the cut or fill the air with dust that will settle everywhere. It also cools the tool, so it lasts longer, and keeps the heat from harming the stone.
But you can cut it dry if you want - just do it outside, when nobody else is around...
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