DRILLING AT THE WRONG SPEED

Using the safe drill bit at too high a speed is usually evident when the safe bit will not bite and the tip quickly becomes burnt or dulled.  You can use higher than normal speeds if you use a cutting fluid to draw excessive heat away from the cutting region.  Using the safe drill bit at too low a speed will still cut, but you will find that your progress will probably be slow and exhausting.  The best plan is to start with a slow speed and increase it slightly until you find the most efficient speed.