Nugget, you need to rough up the edges, and they will flake. You have to keep abrading the edges you want to flake. When you flake all the platforms, and are ready to make another pass, abrade the edges, again, and make new platforms, and flake away.
You can flake a smooth edge, but you get better flakes, and it makes it so much easier, if the edges have been abraded. I watch Claude VanOrder, and Eddie, and Bone pile, and others, and they abrade the hell out of the edges. Eddie, if you go camping at any of these Knap-ins, I would highly suggest, you leave the Kilt at home, and don't bring up anything that might bring up the subject of a kilt. I also suggest you wear long pants, and long handle under wear, and don't bother with deodorant, or bathe for awhile......oh and wear loafers, so you don't have to tie, and untie them. If you get my drift......
Wayne