Carbide vs. Steel Stiffness

​This is purely theoretical, but considering that carbide is 3 times stiffer than steel, to match a 3/4" shank carbide endmill, a toolholder would have to be 2.25" in diameter (if there was a through hole it would have to be 3"!). Of course there is a lot more going on. The mechanical leverage of the long endmill may put too much stress on the toolholder connection and the cost of a long solid carbide endmill may be prohibitive. But it does make you think about tool and toolholder choices. To increase stability, a longer carbide endmill, in place of a long steel extension, may be a viable alternative.