If my shop has been unheated for some period of time I turn the Bot on and run my table surfacing routine without a bit in it just to exercise and warm up the motors and the of course the spindle. Don't know that it is necessary just something I do. My temps range from a cold of 25 to 30 to a high of 90 so not to bad. For me personally if I can't see my breath then shop is OK to work in! Russ