Hold the billet fairly loosely. A tight grip will prevent some of the important wrist motion. If the flake fails to release when you have hit it correctly, check your platform before hitting it again harder. Some factors affecting flake length For long flakes, make nearly 90 degree platform angles. Long flakes need more energy delivered over a longer time to break more rock area.
Force needs to be applied for enough time for the long break to travel the required distance.
Flakes from a gently convex surface run farther. Flakes that follow ridges travel farther. Supporting the flake to prevent it from breaking early by hinging away from the main mass it is being detached from increases flake length. In general, striking more into the mass of the piece, more nearly parallel to the direction of the center plane, results in longer flakes. Initially, thinning is often done from platforms near the center plane following or utilizing relatively pronounced ridges.