Bob, we used to slip cranks on the 1-2-5’s. The basic concept is to put the crank in a lathe and spin it and use a piece of sanding cloth to trim it down. Usually all you need is some racer’s tape to hold the rod in place and spin the crank fairly slow.
Ian’s method of trimming the bearing has become preferable, probably more accurate, and can be done in a drill press that most all of us have, and if you change your mind or screw up, it’s cheaper to change. :)