You are welcome.
I tracked down the other footage, two years ago. And, I always assumed that the knapper was using a forwards drive, to detach the blades. It never occurred to me that he was using the punch as a lever. As a result, whenever I saw the closeup shot around the :50 mark I thought that the strike was simply unsuccessful, and he the end "bounce" of the punch was incidental.
But, the other day, I was watching this, and I realized that the swing does not drive in to the tool. Rather, the swing is carefully designed to pull down, after impact, really hard. And, I realized that he would not be doing that if he were trying to trying to drive off blades, as I assumed. Then, I had to ask my self, is the way that the punch end bounces up, around the :50 mark, actually deliberate??? If so, why???
From there, I started using a regular pen in the crotch of my three fingers to simulate what would happen with a forwards, downwards blow. Sure enough the other end pops up, just after pushing in. Then, I tried to find an antler tool to experiment with. But, I do not have many, of the right size, and shape. So, I decided to start with a steel cylinder, 2.5 inches long.
The arcing blow causes the forwards drive common to "vertical punches". But, the arc of the blow also causes lateral movement, common to "horizontal punches", while the punch tool pivots in the crotch. The process brings together the best of both worlds. And, the effects can be seen in the arrowhead blanks, and the microblades, produced.
