The use of scenarios by user interface designers

The attachment has a rotatable spindle and the horizontal boring machine has a headstock rotatably mounting an axially reciprocable headstock spindle. A dog clutch includes a first clutch member rotatable with the attachment spindle and a second clutch member rotatable with the headstock spindle. The attachment is arranged to be bolted to the headstock with the clutch members in axial alignment. Rotation of the headstock spindle is halted in a predetermined angular position, and the headstock spindle is advanced toward the attachment. A releasable member is operable to retain the first clutch member in an angular position in which its teeth are in correct meshing alignment with the teeth of the second clutch member for smooth interengagement of the clutch members responsive to the advance of the headstock spindle. An operating member is engaged by the attachment as it is bolted to the headstock and operates a control switch which initiates operation of electric and hydraulic control elements to disengage the releasable member from the first clutch member to provide for rotation thereof. The electrical and hydraulic control elements include an operator fixed on the headstock spindle and engageable with a microswitch operator as the headstock spindle is advanced, so that, in effect, as the attachment is bolted to the headstock of the horizontal boring machine, the dog clutch is automatically engaged.