i have a powermatic 209 with straight blades.
last night i was planing some pecan, a 50mm wide piece, a full-thickness knot shattered below the cutterhead. the resulting loose pieces managed to wedge themselves somewhere between the cutterhead and chipbreaker (approx 3/16" welded steel). the chipbreaker mounts on a 5/8 steel shaft.
the shaft deflected to the point of bending, about 3/4 " out of center at midpoint. the chipbreaker and rear guard bent and the knives made contact with the steel chipbreaker.
all the knives folded back and shattered, sending out shrapnel.
the guards kept it all contained with the machine.
the cutterhead bearing is ruined as well.
mmtoolparts and ereplacement parts are great.
ordered all new components and a byrd cutterhead.