i held the notches with my left thumb and index finger and set the point on the leather on my knee almost straight up and used a copper bopper and struck it with a downward 45 degree angle. But the first hit was too soft so the next time i did it much harder. I was real happy that the platform was good and high and was able to kinda do it on both sides. I alway wondered if I would ever get close to figuring that out. OK so i should also be able to knock long thinning flake from one end to the other also as i work the biface right? but this mean that the platform has to go all the way up and then back down removing more material from the ends. I think I bigger pieces