a jig for assembling a rebar pier cage wherein certain of the individual jig elements are laterally and longitudinally adjustable to provide a jig capable of assembling rebar pier cages of various sizes and shapes . the jig elements comprise a plurality of rebar stirrup retaining elements removably secured within longitudinal openings in first and second , elongated channel bars which traverse a rectangular work surface in parallel relationship . opposite ends of the first and second channel bars are slidingly secured within longitudinal openings of third and fourth channel bars which laterally span the opposite , shorter edges of the work surface . means are provided to adjust the longitudinal spacing between each stirrup retaining element in the first and second channel bars , and also the lateral spacing between the first and second channel bars . the work surface is pivotally connected to a table frame whereby the work surface may be moved between horizontal and vertical positions with respect to the table frame and floor .