Need to make a new chuck key.. what material?

[woodchucker]

That's a fair question, I could be clearer I suppose. I'm saying your chuck scroll is weaker than your chuck key. And way more valuable.

I was kidding. but no, it's a 4 jaw, independent, you are trying to get that 1thou out of one side without loosening the other side sometimes because when you loosen it it will move more than 1thou.

 

[Janderso]

I took benmychrees advice and used 4140ht. Came out great.
I also made an extended chuck key using annealed 4140. Hardened it then brought it back to blue.