It is very important to study mechanism in a machine design in order to get an effective and precise movement. There are many ways to convert rotation into reciprocating motion. Each way has unique characteristics. However usually not for long stroke and they have dynamics problem. This problem can be overcome by the cross-screw mechanism without alternating rotation input. Reciprocating motion is produce due to the changing of the screw angle from positive to negative gradually at the end of the screw. Dynamics effect can also be minimised by designing this changing parabolically in maximum rotation angle interval.