Releasable securing devices, such as ball pins, are commonly used for joining the parts of industrial fixtures releasably together.  Such ball pins have a hollow, hardened stem inserted through mating bores in the parts to be joined, the stem terminating in an abutment surface to be pressed against the top side of the parts; and depressible or retractable ball detents near the tip of the pin, to engage the parts on their bottom side. 
Quick connect ball locking devices generally include a plurality of detents, such as balls, trapped within a tube but protruding out openings therein.  A ball actuator is reciprocal within the tube and movable from a first position wherein the balls are retracted substantially within the tube or moved outwardly a sufficient distance to lock the balls within a mating receptacle.  An example of such a ball locking device is shown in U.S. Pat.  No.  5,394,594 which is incorporated by reference herein. 
One of the objects of the present invention is to improve such releasable securing devices by making their length adjustable, to assure a precise tight fit, and permit various strengths of materials to be used to withstand axial loads on the pins. 
Referring in particular to FIG.  1, in previous fastener devices, a compression spring 1 is mounted within an enlarged bore 2 at one end of the pin shank 3 and this spring normally holds a shoulder 4 on the spindle 6 against an abutment 5 on the pin shank.  In this position of the parts the land 7 hold the balls 8 in a projected position.  An actuator button 9 on the shank may be moved manually to bring a groove 11 into registry with the balls and thereby permit radially inward movement of the balls to a release position. 
A problem with these existing release pins is that the springs are captured within a bore of the pin shank and are not easily accessible from outside of the release pin.  Thus it is difficult to change the size of the spring without also changing the cavity size of the pin.  A spring being positioned outside of the cavity allows the release pin to be easily reloaded, and also increases the strength of the release pin. 
Furthermore, existing release pins do not have a shaft design which allows for interchangeable shafts with different lengths and materials.  Thus, there is a need for providing a capability for different shaft lengths and material types as well as various methods of securing the shaft to the release pin assembly. 
Thus, it is desirable to develop a new and improved release pin with an interchangeable shaft which overcomes the above-mentioned deficiencies and others while providing advantageous overall results.