Lockable Type Sack Printer can be used for printing on HDPE woven sacks, pp woven sacks, jute bags, paper bags, multi wall paper sacks, jumbo bags, textile bags etc. The Printer has the feature that the ink supply adjustment is a worm and worm gear system which enables good adjustment of supply of ink and moreover it is self-locking and hence easy to operate. The Printer is easy to lock, easy to remove ink trays, moreover the ink trays are made of brass which is paint and ink resistant and is offered with a three step pulley to obtain three speeds of 1600/ 1950/ 2500 bags/hr. The Printer is sturdy and is offered with bag gripper to ensure smooth movement of the bags. The Printer has the feature that the pressure roller has pressure adjustment on both ends which ensures a zero-zero print on the sack and the total pressure can be minutely adjusted by worm and worm screw. The Lockable Type Sack Printer is designed with drive roller for the endless conveyor belt which is crowned that eliminates the movement of belt side ways and is driven by complete helical gear drive instead of chain drive which ensures zero-zero print registration.