What is the attraction of a spiral cutterhead....
Bill Tindall, E.Tn.
.....on a jointer. It is unlikely that many here have run more lumber across a jointer than I have. I have seldom, actually not in memory, seen any need for a spiral head cutter. By feeding the optimum direction and feeding slowly when necessary I don't get tear-out on board edges. Disclaimer: Except for an occasional use of mahogany the lumber I use is local to the Appalachian Mts. I never work curly hard maple. For the run of the mill oak, maple, walnut, cherry, ash, poplar and the like I don't have any problem with a straight cutter head.
Now it may be that somewhere outside of my experience this cutter head is advantageous. So for those that think they need this feature, or those that have bought it, where has it proven to do something that a conventional jointer cutter head doesn't.
On a planer I have seen two advantages. At least on a large industrial machine the planed surface can be so smooth that one can not see planer marks and initial sanding could be as fine as 150 or 180. And, for those without on-board sharpening the insert bits provide easy "sharpening". And of course on the rare occasions where depth of cut and feed direction will not eliminate tear-out the spiral cutter head likely will yield a tear-out free surface (I am told).
I have put tens of thousands of bdft of Appalachian hardwoods through an 18" Powermatic with onboard sharpening capability and variable infeed rate. A spiral cutter head was never worth the money in my situation for the incidence of tear-out is minor. (I am planing predominantly FAS1F and BTR grade of lumber. Planing lower grade lumber could present more problems with the greater incidence of knots).