self larnin' goin' on--narrowing rear axle

Why waste your time and money machining a bar unless the base stock is free.

Get a turned ground and polished 1045 bar in the diameter you want. It's not that expensive if you get one that's under 48". Shipping goes up a bunch with lengths over 48".

http://www.speedymetals.com/c-8232-turned-grnd-polished.aspx

Pick your OD, bore your pucks and you have an alignment jig. I use a 1.25" TGP bar that is 48" long, about $50 delivered, IIRC. Do one side at a time for most rears.