How to machine Cobolt

[terryw123]

I bought a piece of cobolt blank thinking I could cut and shape it to make a lathe cutting bit. But that stuff is much harder than I thought. Carbide won't touch it. Any ideas how to cut it?

 

[darkzero]

Unfortunately the easiest way is to grind it.

 

[cathead]

The unseen hazards of grinding on cobalt are not worth the risk. Not only is the inhalation of the dust dangerous, it
is also likely carcinogenic. Exposure can cause an allergic reaction and damage one's internal organs. OSHA has
set exposure limits for cobalt exposure for good reason.

 

[Tozguy]

If you are talking about Crobalt blanks then yes you can grind them on a grinder like HSS. The caution about toxic particles from a grinder, not just for Crobalt, should be heeded. It is important to wear a certified mask or use an efficient vacuum system right on the grinder.
Crobalt is a cast alloy that has a hard skin. Do not quench when grinding.
Is this what you have?
http://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=32&Itemid=46

 

[darkzero]

I just assumed the OP was talking about HSS-Cobalt tool blanks like M35 or M42 tool steel. But with the misspelling in the title it could be either I guess

 

[terryw123]

This is what I have from ebay. http://www.ebay.com/itm/251846364385?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[darkzero]

Yep, that is M42.

 

[terryw123]

Is M42 good for anything? What are the advantages and disadvantages? What an it be used for?

 

[darkzero]

Here's some general descriptions on wiki (scroll down to types).

https://en.wikipedia.org/wiki/High-speed_steel

I didn't know M35 & M42 had different names, HSS-E & HSS-CO

 

[Tozguy]

Terry, what do you mean when you write 'carbide won't touch it'?