which matieral for shaft

[jwest]

Hi, I'm building a budget cnc using linear bearings. But what material do you recomend for the shaft, I'm looking at around 15mm in diameter and 750mm long but should I go for mild steel or aluminium, or pay more and go for stainless steel? is there much of a difference?

Many thanks

[diecutter]

I would stay away from aluminum because it wears way too quickly. Stainless steel is pricey and hard to work with. Mild steel is ok, but drill rod is not much more expensive, has excellent finish and tolerance specs., and is available at all machinery supply companies such as MSC and Enco. I would go with a larger diameter rod for a span that long to increase rigidity without driving the cost up too much.