: How much was the upgrade?

The H6755 cutterhead is on sale through Grizzly for $475 (plus shipping). You get the cutterhead with 72 inserts plus 10 extra. One thing they don't tell you is you need to buy at least one new bearing as the one on the support side of the cutterhead is pressed on. My local NAPA had one for about $20. The whole upgrade took about 5 hours. It could have been quicker. The gearbox gave me some issues. Grizzly also has spiral cutterheads made by Byrd (Shelix brand) for about $100 more. The Grizzly brand ones are what they put on their newer industrial jointers and planers. For life-time costs each time I get the blades re-sharpened it costs about $35. With the carbide inserts I get a life-span equal to about 16 re-sharpenings. That's $560 right there plus add a couple sets of $50 blades. One thing I noticed is the planer doesn't work as hard with the spiral head. It can take a deeper cut at a faster rate than the old HSS knives. I should be able to save some time planing... The old straight knives would have just hacked at the gnarly maple. It'll be interesting to see how it holds up. I think it'll be worth the money spent.

Below is the Link to Grizzly. They have cutterheads that fit most 15"+ planers on the market. (I have no connection with them by the way.)

Dan