Great input guys!
Johnathan, one of the guys I know tried wrapping the indirect tool with leather to help keep it under his knee. It didn't work too well. It seems the best way to keep it there is to sit on a low seat and elevate your foot so your knee makes more of a sharp angle and, therefore, you can get a better grip behind the knee.
Justin, I've tried notches on the end of the percussion tool and I tend to snap off large pieces off the blades. It almost looks like I've taken a bite out of the arrowhead. The tool will sometimes slide around without the notch but you don't need too much inward pressure... just change the angle of the strike a little so that more of the force goes into the blade.
I filed it back out Patrick and then got good results again. To be honest, It'd probably work well with a larger billet, but an antler the size of a quarter, most of my platforms were shaving the notch and not disconnecting the flake. I had the best results changing the angle of my biface to match whatever angle I needed to strike off, and in a lot of cases, changed the point of contact with the billet to match larger curvature or smaller curvature of the billet for larger or smaller platforms. Obviously in that situation, lots of different billets would shine, but soon as I get a little more time and get some trades caught up, I'm going to fiddle with different wood billets, mostly because that's what I have most available to me. I can't see why wood is suitable for direct and not indirect.
