Abstract: The disclosure concerns an apparatus that increases the utility of the ink jet printing engines by allowing the engine operator the freedom to select the spacing between the ink emitting nozzles of each inkjet print head and a printing substrate. The preferred embodiment of the present invention comprises a reciprocating carriage assembly having twelve individual ink jet pen receptacles and a manual vertical adjustment feature for precise control of the spacing between the printing substrate and the print head(s). In one embodiment, the inventive carriage assembly height adjustment features dual, manually-actuated axial screws that cooperate to evenly raise and lower the carriage assembly. Preferably a third mounting point ensures parallelism when the carriage assembly is raised and lowered. In use, the entire carriage assembly, including circuit boards, ink jet print heads, and electronics all move in unison when the axial shafts are rotated.