Positioning base the decision of gear shaft upon the surface of the main processing order, to a huge extent depends on the selection of locating datum structure features and the main shaft of the shaft parts upon the surface of the main location accuracy requirement is set the axis because benchmark is the ideal not just make sure that benchmark is unified, and make the locating datum and the design datum coincidence outdoors circle designed for crude benchmark additionally, upon both sides of a sharp hole for fine benchmark concrete also take note the following factors: (1) when the choice between machined surface area when the position accuracy of high, greatest done in a clamping surface area processing (2) for tough machining or when two end middle holes (such as for example spindle cone hole) planetary gearbox cannot be used meant for positioning, to enhance the stiffness of the process program during workpiece processing, only cylindrical surface or cylindrical surface and 
one end center hole can be utilized as positioning reference
