After a chuck portion chucks a workpiece holding body which aligns and holds a plurality of workpieces on which components are to be placed, the posture of the workpieces held in the workpiece holding body is adjusted due to rotation mechanism by rotating the chuck portion around an axial line which extends in an aligning direction of the plurality of workpieces held in the workpiece holding body. Then, a placing head places the components on each of the plurality of workpieces which are subjected to posture adjustment.

After a chuck portion chucks a workpiece holding body which aligns and holds a plurality of workpieces on which components are to be placed, the posture of the workpieces held in the workpiece holding body is adjusted due to rotation mechanism by rotating the chuck portion around an axial line which extends in an aligning direction of the plurality of workpieces held in the workpiece holding body. Then, a placing head places the components on each of the plurality of workpieces which are subjected to posture adjustment.

An improved spindle assembly for a Davenport multi-axis screw machine is adapted to adequately hold one-inch round bar-stock in a collet against movement relative thereto attributable to machining operations performed on a cantilevered length of bar-stock held in and extending beyond the collet. The spindle assembly may permit the use of the screw machine on materials thought heretofore to be too difficult to machine on a screw machine. Cam surfaces on the inner spindle and collet may be coated with a low-friction material. A stress-relieving connection between the inner spindle and collet is provided.