Jules and all,  I use a table saw to do the job just before I put the
front face on, but after the other 3 sides are glued together.  I set
the fence on one side of the saw blade to cut one side and put the
fence on the other side to cut the other side.  The blade is just
raised enough to cut the thickness of the metal.  Since the same size
of cut is used in several sizes of pipes, changes are few.

Russ Doering