Thanks Guys!
Today I'm going to setup the mill to square the ends of the six leg tubes, to do this i'll remove the big vise, and place the 12x9x6 angle plate on the mill. Then I'll put my side plate with end stop on the angle plate, and position it all on the table so the 3" face mill can power feed across the end of the tube. Next, I marked the location of the angle plate with a Sharpie Pen. Now I can extend & rotate the turret so the spindle is in the center of the tube. After locking the turret bolts, I removed the angle plate and pushed it out of the way!
In order to get really accurate squareness on the ends of the tubes, i'll need to tram the mill's head at this new location! To do this I'll se a 12" diameter steel disk from the lathe. as its been cut & ground perfectly flat & parallel! I placed the disk in same location as the Sharpie lines, and put a dial indicator in the spindle. After sweeping the circle and getting 4-zeros, I' lock the head bolts and put the angle plate back!
All I needed was a square to align the angle plate, because the center is not critical.