The present invention relates to a general purpose clamping device. It comprises a straight shank with the lower end attached to a short cylindrical sleeve and a movable arm sliding over the shank. Feeding through the free end of the movable arm is a threaded rod with clamping pad and turning handle at the lower end and upper end respectively. The present invention is designed to hold a workpiece tightly, quickly and conveniently on the working surface of a table, workbench or machine tool. And the invention can be relocated easily over the workbench made of wood or metal, or over the working surface of a machine tool. Attachments are provided to enhance the functionality of the invention. A Y-axis attachment assembly is adapted to being slidably mounted on the straight shank to hold a second workpiece along an axis that is generally perpendicular to the vertical clamping direction of the multi-function clamp.