When by statute or by these Rules or by a notice given thereunder or by order of court an act is required or allowed to be done at or within a specified time, the court for cause shown may, at any time in its discretion, (a) with or without motion or notice order the period enlarged if request therefor is made before the expiration of the period originally prescribed or as extended by a previous order or (b) upon motion made after the expiration of the specified period permit the act to be done where the failure to act was the result of excusable neglect; but it may not extend the time for taking any action under Rules 50.02, 52.02, 59.02, 59.04, 59.05, 60.02, 72.02, 73.02 and 74 except to the extent and under the conditions stated in them.