Following,  is the axle construction.
The axles were turned at each end to fit the wheels. One end was left a little longer to chuck on for the quartering of the keyways.
Here are all three axles with their keyways cut.
Test fit of a key.
A keyway was cut in one end of the axle, the rotary table was then turned 90 degrees, and the other keyway cut.
The keyways were cut in the wheels with a broach.