One step forward- - - -two steps back! I set up a worn rocker shaft in the lathe, and did a little whittling on it with some mixed results. First- - - - -those shafts are HARD- - -but only where the rocker arms run. The space in between rockers is considerably softer. The hard areas are also deep- - - -no need to worry about cutting through into softer metal. It looks like machining a shaft down to 3/4" diameter will take care of even deeply worn areas, which is about a .040" (1MM) reduction in diameter. Shouldn't affect the rigidity of the shafts at all. The original diameter is around 0.790". 3/4" (0.750) ID Torrington bearings are plentiful, and fairly inexpensive. Of course, if the idea of fitting Torrington bearings to the rocker arms doesn't appeal to you, installing thin wall bronze bushings in the rocker arms to fit the reduced size shafts would be a simpler, and much less expensive option.
Downside- - - -unless a follower rest is used, the shaft will flex and make it difficult to maintain a uniform diameter from end to end while machining. That's particularly true since you'll be making an interrupted cut across a lot of holes, and dealing with different hardnesses of metal along the way. A tool post grinder will probably be the right way to go to get a uniform diameter and finish from end to end. Obviously, thin bushings will need to be installed in the support stands to adapt to the slight reduction in shaft diameter. Fun project!
Jerry
