Jon Elson writes:

What use would an 18" straightedge be on a Bridgeport?

I was only wanting to work on the knee-to-saddle ways (25 inches long, the
table and column seem OK). At 2 inches wide, and trimmed to a truss
profile, a 24-inch long slice of granite should be well under 20 lbs.

I suppose for a 42-inch table, the stone would be over 100 lbs, and one
would be considering some kind of tool-balancer suspension.