A similar case involving a press-fitted dove. tail insert (a). For looser tolerances and ease of repeated assembly/disassembly it is preferable Initially to have a running fit between dovetail and slide and add a slot and oversize pin (b).

(e) Design For Ease Of Assembly And Disassembly

Sometimes an alignment pin has to be inserted in a blind hole e.g. when one part is too long and the aligning hole is too far away from the side of the workpiece to permit a transverse expulsion hole. In such a case an air-vent hole (a) or a flat on one side of the dowel pin (b) is recommended In order to prevent air compression during assembly.

Relying on threads for alignment is not reliable (a). For threaded plungers alignment should be provided by adding a small, smooth, cylindrical shaft at the foot of the plunger (b). In the case of long plungers, two aligning diameters are desirable (c). These will ensure squareness in assembly.

In assembling a pin, plunger or shaft with the mating hole, avoid a square-ended shaft entering a square shoulder (a). Countersinking the bore and the entering portion of the shaft facilitates smooth entry without nicking corners (b).