A machine to overturn workpieces can include a mechanical arm, a holding member coupled to the mechanical arm, and a workbench positioned adjacent to the mechanical arm. The workbench can include a base plate and a first positioning assembly. The base plate can define a slot. The slot can extend towards and through a sidewall of the base plate, and define an outlet at a portion running through the sidewall. The first positioning assembly can be positioned on the base plate adjacent to the slot. The first positioning assembly can be configured to manipulate and position the workpiece. The mechanical arm can be configured to drive the holding member through the slot to attach to and hold onto a surface of the workpiece facing the base plate, and move the workpiece away from the base plate via the outlet.