On Fri, 31 Oct 2008 10:23:47 +0100, "Steve Lusardi"
wrote:

You really should use a cast iron round. Cast iron is a dead material,
dimentionally stable and easy to machine. Steel is absolutely the wrong
material because it will sing when subjected to vibration and amplify tool
chatter.. This is the reason that all machine tools use cast iron. Don't
reinvent the wheel.
Steve

Except:
-the best chucks are made of steel
-many of those steel chucks come with steel back plates
-there are plenty of load bearing steel components on machine tools
-steel is stiffer than cast iron

--
Ned Simmons