A nail locating device is adapted for locating a magnetically attractive nail that was driven into a non-magnetically attractive board, and includes a seat, an indicator rod and a biasing spring. The seat is adapted to be moved on a surface of the board, and confines a vertically extending receiving...http://www.google.com/patents/US6366073?utm_source=gb-gplus-sharePatent US6366073 - Nail locating device with pivotable magnet supporting indicator rod
