By about 200 , Roman craftsmen used several types of ironheaded hammers for wood working and stone cutting. A Roman claw hammer dating from about 75 had a striking surface on one side of the head, and a split, curved claw for pulling nails on the other side.
Drilling Speeds and Feeds . The speed of a drill is measured in terms of the rate at which the outside or periphery of the tool moves in relation to the work being drilled. The common unit and term for this velocity is surface feet per minute, abbreviated sfm. Every tool manufacturer has a recommended table of sfm values for their tools.