Those that plane a lot of wood might be interested in this. Over the weekend I took the plunge and upgraded the cutterhead on my 15" planer from the standard high speed steel (HSS) knives to a spiral one with 72 carbide inserts. Each insert is made of solid carbide which last about 4X longer than high-speed steel. Each insert has four sharp edges. That's equates to about 16 sets of HSS blades. It should pay for itself... eventually. Also if you hit a piece of steel/rock while planing you only have to reset 3 inserts instead of 3 whole blades. I tried it out on a test piece of some really gnarly hard maple. It was a cutoff with a couple knots and some nasty grain in it. The new cutterhead performed wonderfully. No tear-out to speak off, even while taking some deep cuts to really test it. I'll need it when I plane a bunch of curly maple for a kayak this winter. I'll keep you posted...

Dan