Abstract: Screen printing apparatus incorporating drive means for a squeegee comprising a drive motor, a lead screw rotatable by the motor and a rider for the lead screw, said rider being coupled to a mounting for the squeegee preferably through stroke adjustment means and the lead screw having two oppositely handed threads thereon such that rotation of the motor causes reciprocating motion of the rider longitudinally of the lead screw at substantially uniform speed.Adjusting means to adjust the distance between two members such as a printing head of screen printing apparatus and a table on which articles to be printed can be laid, comprising a pair of coaxial shafts, eccentric members secured on the shafts, bushes secured to respective ones of said members and means to rotate the shaft such that the eccentrics when rotated in the bushes cause the members to move relatively to one another by the sum of the eccentricity of the two eccentrics having regard to the angle through which they are rotated.