pic: Stress plots related to broken output shaft

[M. Mellott]

One option that comes to mind might be to use a tool that has radii in the bottom corners (or completely rounded on the bottom and cut your groove a few thousandths deeper) rather that sharp points. Sharp edges are stress concentrators, so the blends might remove some of the stress points.

Now, one might say a completely rounded groove bottom might also take away too much of the vertical side walls of the groove and defeat the primary purpose--holding a snap ring and supporting an axial load...but some snap rings have rounded cross-sections, so...