Wrenches Wrenches—a very good name for this tool in that all too often it is the condition of a worker’s back after misusing a wrench. (Wrenched back, get it?) It is not only a back that can be injured, as we will see after our discussion. Guide for Discussion Proper Care Inspect on a regular basis Replace sprung jaws, cages and faces Replace all bent handles Keep the jaws sharp Keep the wrench clean and free of grease and oil. Proper Use Always use the proper size wrench for the job. Never use a shim to make a wrong size wrench fit a nut. ...