Over a number of iterations, I have come to use :
150cm / 59" for width
130cm / 51" for depth
100cm / 39" for enclosure height above the table
Enough clearance on the sides and back for clean-up, tall enough to never bump my head, and just enough space at the front of the machine to act as a dropped bit (cushioned) landing zone as well as a place for general mess, wrenches, pens, post-it notes, clamps, etc…
The top of the enclosure rests on top of table, so those dimensions include space for the 3/4" walls all around.