Never walk away from a coffee roaster when it is in use!. You should be in arm's length of the roaster, within 3 feet! Coffee roasting in its essence is drying out a woody plant material and bringing it to the brink of fire. No commercial / professional roaster ever leaves a roasting machine unattended, and you shouldn't either! While the beginning stages of a roast can progress slowly, called the drying phase, things happen very fast at the end of a roast: each 10 seconds that elapses can produce a different taste result. You need to be there for it!