Thanks for the complements. I should mention you're looking at the backs (insides) of the wheels. The outside is not as deep, and has corner rounding on the spokes.
Last year, I'm pretty sure we did nearly identical wheels in two operations only on the CNC mill. This year, I forgot exactly what I did last year to finish them off, while having only very little left to hold. So, I did them in two operations in the CNC mill, and left a little bit of the groove unmachined, so I could hold them. Them I finished off the groove in the manual lathe. You can see where the surface finish changes.
In the mill, I held them just in some aluminum softjaws, and went around the outside with a really el cheapo junk HSS woodruff keyway cutter. It took much longer than I'd like due to the HSS cutter, but it worked fine. I'd like a bigger carbide T-slot cutter or something like it to do the tread grooves., but they're $$$.
On the manual lathe, it was actually a pain to finish off the groove, because the wheel is so thin and light that it just resonated and chattered like crazy, leading to horrible surface finish there. But, it's under the tread, so you'll never see it.
