If the high stress point in an axle is just inboard of the cone, perhaps it would help to chamfer the inboard side of the cone a few thousandths. This would distribute the stress over a greater area of the axle surface, and it wouldn't require taking off much metal. A radius would of course be even better, if you had the tools. This would certainly help on a threadless axle, but probably would not reduce the stress at the thread minor diameter for a normal axle. But if the cone were a little deeper, so there could be a close fitting annular portion inboard of the thread, (ending with a chamfer or radius and bearing on the unthreaded inner part of the axle), we might really improve things. Remember the Paramount axles of the 1939 to 1941 period which had threadless cones positioned by nuts outboard of the cones? Now it all makes sense. Any stress analysts out there who can evaluate this thought?
Chris Andrews
Sequim, WA