20MM Case Hardened or Bright Steel

[simso]

Hey guys, Im using 20mm round for all my linear movements with the open linear bearing so that way I can support the shaft from underneath, Its not easy to find in Aussie 20mm ground case hardened steel. I was looking at bright steel which is what the steel stockists say they use in CNC applications, the bright steel is like 15 bucks for a 3100mm length. Where as the ground case hardened is 236 for the same length. Anyone got any ideas or used bright steel. Recommendations
Thanks

[cncuser1]

Originally Posted by simso Hey guys, Im using 20mm round for all my linear movements with the open linear bearing so that way I can support the shaft from underneath, Its not easy to find in Aussie 20mm ground case hardened steel. I was looking at bright steel which is what the steel stockists say they use in CNC applications, the bright steel is like 15 bucks for a 3100mm length. Where as the ground case hardened is 236 for the same length. Anyone got any ideas or used bright steel. Recommendations Thanks

You have to find out what it is about 20mm ground case hardened that you need and see if bright steel has it.

Some of the thinngs to look for are the Hardnness and surface finish and straightness.

Find out what the hardnness measurement is for 20mm ground case hardened , probabbly measurred on the brinell hardness scale, the measurrement, my guess is about 55 to 65.

Does brighht steeel hass a similar hardnness?

Do the same for surface finish and straightnness.

[simso]

How stupid of me. I actually have a hardness tester at work,Ill give it a go. Thomson units are 60 rockwell c. So if I can get bright steel in the same hardness laughing. They have a machining size tolerance also on the steel I will have to check the specs
Thanks for the feedback

[epineh]

I used 40mm bright steel round bar for my x-axis and 30mm for my y-axis, 1200mm unsupported for the entire length (x), works a treat, I can link my build log if you want. Used skate bearings running on all 3 axis's, happy as.

If you want harder, I'm not sure of the exact name for it, but it is the polished hardened chrome bar they use in hydraulic's, it is supposed to be pretty cheap as well. Found out about it after I built my machine...

Russell.

[simso]

Yep link me thanks

[epineh]

http://www.cnczone.com/forums/showthread.php?t=22101

Russell.