Small scale milling machine

A small scale milling machine of the type comprising a machine base having an upright rotary wheel, a rotary column sleeve fixedly secured to said rotary wheel, a machine head mounted on said rotary column sleeve and moved vertically along a longitudinal track on said rotary column sleeve, and a driving motor mounted on said machine head and controlled to turn a cutting metal-working tool against the workpiece, wherein:

• said rotary column sleeve comprises a longitudinal dovetail tongue at a front side thereof engaged with a longitudinal dovetail groove on said machine head, a unitary longitudinal rack raised from said longitudinal dovetail tongue and engaged with the inside of the longitudinal dovetail groove of said machine head, a longitudinal track at one lateral side of said rotary column sleeve, two stop blocks fixed to said longitudinal track at different elevations to limit the vertical moving distance of said machine head, a scale on the front side along said longitudinal track for measuring the distance between said stop blocks, a transverse through hole near a circularly curved bottom end of said rotary column sleeve and fixed to said upright rotary wheel of said machine base by a screw bolt;
• and said machine head is suspended from a vertical mounting frame being fixedly secured to a retractable support on said rotary column sleeve, said retractable support having a fixed bottom end inserted into said rotary column sleeve and fixedly secured to the inside of said rotary column sleeve and a movable top end fixedly connected to said vertical mounting frame, said vertical mounting frame having a top end fixedly secured to the movable top end of said retractable support and a bottom end terminating in a transverse bottom plate fixedly secured to the topmost side of said machine head by screws.