Quote Originally Posted by Boyan Silyavski View Post
Even so if you are not milling steel and pushing it to its limits the spindle will NOT fail. It will heat up to ~60C, hot to the touch, but will continue to happily cut normally wood or light cuts in aluminum. It happened to me a couple of times when i was testing the new machines and the relay was not connected, so i had to manually turn on the pump. No smoke or whatsoever.
I'll Confirm and Back up this. For Jobs less than 30-45 I don't bother connecting the hose pipe and I exclusively cut Aluminium. Also like Boyan unknowingly due to my error I've cut jobs lasting 2hrs+ without water being on and not had any issues. Take the Fan off your air cooled spindle and watch it melt down in 10mins.!!