The method I've heard about, but never actually seen being done, involved spinning the rod, and applying a thin layer of Babbit from a spray nozzle. I think the process was called "Centri-Cast". (Centrifugal casting?) Then the oil grooves were machined into the Babbit material after it solidified. Final finishing included boring the Babbit to whatever undersize was necessary, or cutting it to standard diameter. The rod and the cap has a shallow depression machined almost all the way across the bearing surface with a raised edge about 1/16" wide to act as a retainer for the soft metal. When the rod is machined for an insert bearing, the Babbit is melted out, that raised lip is machined away, and the rod is honed to the correct diameter to retain the insert correctly.
Jerry
