Abstract: A truss rod for selectively bowing the neck of a stringed instrument includes a segment of round stock having a pair of threaded ends, one set of threads in a first thread direction, and the other set of threads in the reverse direction. Complementary threaded blocks are threaded onto these threaded ends, and the blocks are secured to a length of flat bar stock. A head bearing a socket is fixed to an end of the round stock, so that turning of the head turns the round stock. The reversed nature of the respective threaded ends causes the length of the portion of the round stock between the fixed blocks to either increase or decrease when the round stock is turned, which correspondingly causes the flat bar to bend either in or out.