I have made axles by cutting and welding old ones to the length I needed.I am far from a professional welder, but follow the basics. I worked with 1 1/8 round, V it 1/8 of a inch or less, lay it in a angle iron to keep it straight. Run a bead down one side turn it over do the other, let it cool, chip the slag, and wire wheel it to get the slag all out. After root pass I use 7018. Make pass on each side and clean, repeat , don't over heat it, keep a eye making sure it stay straight.

I have made a spool or 2 from old disc blades and pipe. They never failed, but as I had real ones from junk disc I replaced with the real thing. The axle nuts need to be really tight no matter what and I have run used blades that the center holes was a bit big (not a 1/2 inch to big, maybe a 1/4 to big) without cutting the axle but do weld them up.

I feel bearing for heat at lunch time. Have drill a very small hole in the seal and needle point fitting on grease gun and added grease to sealed for life bearings. Put a little silicon gasket maker in the hole, and got a lot more acres out of a bearing.