[Geary]

Mike .. could you possibly tell us the dimensions, application, and an opinion of this shafts material? It just seems like quite a large keyway on a relatively small diameter shaft.

I have to wonder whether core strength was compromised in just the short keyway portion of the shaft during the heat treatment process, due to the irregular cross sectional shape. That's kinda what the photo looks like to me .. a large hard zone around the keyway, stealing uniformity from a core that's skewed off-center. Copper coating the keyway prior to heat treatment is a probable solution .. or replacing the key with splines. .. (just a layman rambling) ..