41. Nuts and water jackets are often chrome-plated, and wood screws are turned so that the slots in the screw heads line up perfectly. 42. Drywall screws heads have a curved taper, which allows them to self-pilot and install rapidly without having to be punched through the paper cover. 43. The electrical short during last month's launching of the shuttle Columbia was caused by a wire rubbing on a screw head , NASA said Monday. 44. Q . I am putting up dry wall, with plasterboard panels and joint compound in the joints and over the nail or screw heads . 45. A typical simple screwdriver has a handle and a shaft, and a tip that the user inserts into the screw head to turn it. 46. When I saw them for the first time, I thought maybe the carburetor-like work was mixed media : the screw heads looked so real. 47. If the screw heads are not sealed, water from inside the cabinet will flow by capillary action into the sealed evaporator space within the foam. 48. There are at least a half-dozen different types of screw head openings : slotted, phillips, bistro, Robertson, Tory and clutch head to name a few. 49. Drywall screws hold well and you can use the screwdriver to drive them, but the screw heads may require more joint compound to cover them. 50. But technicians later traced the problem to a bent wire whose insulation had been torn away, which shorted when it touched a metal screw head .
