Adjustable positioning structure of a shaft member

1. A shaft member comprising an inner tube, an outer tube, and an adjustable positioning device, wherein the inner tube includes a plane axially formed on a peripheral side thereof, wherein the plane includes a plurality of holes arranged thereon and spaced apart from each other equally, wherein the outer tube includes a cutout disposed on one end thereof to receive the inner tube, wherein the adjustable positioning device includes a fixing seat, a retaining block, a stop switch, and a resilient element, wherein a cross section of the fixing seat is formed in a U-shape pipe shape to face to an outer rim of the one end of the outer tube which includes the cutout, wherein the fixing seat includes two extending sides, wherein the retaining block is formed in an elongated Z shape and is axially defined between the two extending sides of the fixing seat, wherein the retaining block includes a pressing portion and a bore fixed on one end thereof, wherein the retaining block further includes a lock tab extending outward from another end thereof, wherein the stop switch is formed in a slidable cover shape to be covered to the fixing seat, wherein the stop switch includes a shoulder disposed on one end thereof to be inserted in the bore of the retaining block to stop the retaining block to be pressed and to operate, wherein the resilient element is defined between the retaining block and the stop switch to contact with the retaining block and the stop switch, wherein the lock tab of the retaining block is retained in one of the plurality of holes.

2. The shaft member as claimed in claim 1 , wherein each extending side of the fixing seat includes an elongated orifice parallel to the inner and outer tubes and an axial bore perpendicular to the inner and outer tubes, wherein the retaining block includes an axial stem extending outward from two sides of a middle section thereof and inserted in the axial bores of the two extending sides of the retaining block, wherein the stop switch has U-shaped cross sections and includes the top and two sides extending from opposite sides of the top, with the retaining block located intermediate the outer tube and the top and intermediate the two sides of the stop switch, wherein the stop switch includes two defining protrusions fixed on an inner surface of each of the two sides thereof and retained in the elongated orifice of the fixing seat to allow slideable movement of the stop switch parallel to the inner and outer tubes, and wherein the stop switch is limited to slide in a certain range.

3. The shaft member as claimed in claim 1 , wherein the adjustable positioning device includes a limiting bolt inserted between the two extending sides of the fixing seat.

4. The shaft member as claimed in claim 1 , wherein the fixing seat includes a C-shaped engaging portion disposed on one end thereof to match with a locking element and positioned in the cutout of the outer tube.

5. The shaft member as claimed in claim 1 , wherein each extending side of the fixing seat includes a concave recess formed on one end thereof, wherein the stop switch includes an extension disposed on one end of each of two sides thereof and locked in the concave recess of the fixing seat to position the stop switch.

6. The shaft member as claimed in claim 1 , wherein the retaining block includes a fitting projection extending upward, wherein the stop switch includes an insertion extending upward on a top surface thereof, and wherein two ends of the resilient element are fitted with the fitting projection of the retaining block and the insertion of the stop switch individually.

7. The shaft member as claimed in claim 1 , wherein the lock tab is tilted.