Thanks all for the advice.
I'm pretty irritated at the moment, as it appears I ruined one of the wheels while drilling the hole for the cotter pin. I got everything set to the right tightness, then marked the hole in the axle with a punch. I tried to find the valley in the thread, but it still seemed to completely distort the threads when I hit the center punch. Getting the nut off then obviously required putting the nut in the vise and twisting the gear rod.
I was cursing most of the time and just trying to get it off (not taking my time), and it appears I chewed up part of the wheel on the corner of the vise somehow.
Two more questions from this frustrated builder:
1) How do you drill for the cotter pin without completely trashing the threads (and making it near impossible to get the nut off)? Should I just drill it with the nut in place?
2) Does this wheel appear salvageable? Any advice?
