I read this thread a couple of weeks ago and ran across what you would refer to as "tough" steel in a rear hub of mine. I have a metal lathe, so I thought I'd try opening up the hole- I have a carbide boring bar and even that was having a hard time cutting into the hub steel. Then I heated it all up to a dull red and re- tried it in the lathe- this time it did start to make chips, but it was dulling the carbide tip on my cutter, so I stopped. If you are only going up from 7/16 to 1/2" then a sander disk in a dremmel tool is about as easy as it gets, although if you need the hole to be concentric to the outside diameter of the hub, you still need a lathe of some sort to spin the part while grinding. - be sure to cover all the surfaces of your lathe as grinder dust is very detrimental to machinery!Hey, any thoughts on drilling out a wheel hub, super hardened steel. Special drill bit? grinding?