Rotary type electronic part

In a rotary type electronic device having a stationary casing and an axially slidable and angularly rotatable operating shaft having one end disposed for axially sliding movement along a longitudinal direction in the casing, a detentable cam disposed in the casing having a slidable portion with an end face perpendicular to the longitudinal direction which is engaged by the one end of the operating shaft such that the shaft can be slid axially inwardly and outwardly of the casing to engage and disengage from a detent position of the cam in the casing,

• the improvement wherein said one end of the shaft is formed with a conical tip portion, tapered in the inward longitudinal direction from an outer diameter side to an inner diameter side, and with a retaining circumferential groove formed outwardly of said outer diameter side, and wherein said end face of the cam is formed with a central hole for inserting and retaining said one end of the operating shaft, said hole having a diameter larger than the inner diameter and smaller than the outer diameter of the conical tip portion, and with cutout portions on opposite sides adjacent to the central hole forming deformable bridging portions therebetween which elastically deform to allow insertion of the conical tip portion of the shaft in a direction perpendicular to the end face during assembly and which thereafter remain engaged with the retaining groove of the operating shaft.