I need some 20mm steel bar for an axle ,for a lathe moving skate im making, but i need something that isnt bent. i went down the stockholders and picked up some 20mm bar, its always a bit bigger, so i thought i can turn that down in the lathe, its only 300mm long ,but ****** as a fart.Bent as a nine bob note. so much run out its untrue.so i need to order some from the bay, but unsure what you would call it aside from mild steel bar? I just need it true.Any input ?