[CNC-Dude]

Hi Group,

I am building my CNC Plasma Cutter Y Axis and will be usign 12 mm linear ball bearings. I have some 12 mm shafts but want to make my Y Axis the longest axis, so will be buying new steel to get this done.

I went to Metal Supermarket who is the best place around here to get the metal rods. I am thinking about going with cold rolled rounds. Any suggestion here on whether cold rolled is better or worst than hot rolled? If I am not mistaken, hot rolled should have better tolerance, but I am not certain this will be so critical as long as the bearings move smoothly across the rails.

The question I have, however, is about grades. There is a gazillion of them and I think I understand this has to do with hardness and how they react to tension. I am thinking I should not care too much about this either, as after all I'll me moving a measly plasma cutter, so there is really not a lot of stresses the system will be subjected to.

Any words of sapience here will be appreciated. Thanks!

[ger21]

If you're using bearings like these, then you must use hardened, precision shafting, or you'll get grooves in them almost immediately.
12mm Linear Motion Systems:Ceramic,Miniature Ball Bearings

[ViperTX]

Thompson Linear Race Shafting.

Paul