Do they spin freely ?From there I welded a washer to the heads and ground them to the same size as the outer diameter of the inner bearing.
Yes.Do they spin freely ?
Only doing the above you run the risk of the bearing shield rubbing on that washer ?
The washers you welded to the heads should be the same diameter as the inner race's , so only touching the inner races of the bearings.
Even my Sturmey Archers hub brakes suffer from this.
I think it's this only 3/8". Will have to stop by menards to check.12mm hubs are fine. Sturmey use 12mm in their single sided drum hubs. Having said that they use a 12mm bolt. My own 12mm hubs use an 8.8 high tensile 12mm bolt. I'd worry about that 3/8 bolt bending. Ive seen plenty of 3/8 axles bend even in regular bike use and mounted at both ends.
I find potholes are much harder to avoid on a trike due to the width of the machine than a bike.
The 12.9 will mean zero bending but a bigger chance of snapping over an 8.8. I have no idea whether my mid tensile or your extra high tensile is the better choice of the two. If mine ever bends I'll move up and if yours snaps you can move down on the scale. Undoubtedly better than any 3/8 bolt either way.
Sorry I was not precise enough , I can see the crazy angle , however is that at the wheel/kingpin joint or the frame to wheel arm joint ?The wheels aren't perpendicular to the ground.