Matt, I cut the groves in with a side grinder and clean the ridges up with the edge of the platten. Then heat the zig zagged blade almost to welding heat, almost, then flatten the entire blade. Since it has some geometry already, I have to, more or less, take the kinks out. Notice that the general profiling has been done prior to the grooving and flattening (the embryo), so that means less distortion for the pattern as long as you just concentrate on working the grooves out.
This requires planning ahead for the flattening. Number one, the blade embryo has to be thick enough to allow the loss of the material that goes away with the formation of grooves. Number two, the major profiling should be done at the embryo stage, so no (not much anyway) profile changes have to be done. There will be some spreading and legthening of the blade during the flattening stage.
I achieve this pattern different than most. Most use fullers, then grind.