That "Filed" edge
It's pretty common knowledge that Howard Hill used a file to sharpen his famous concave edge Hill broadheads. He'd designed the head to have minimal surface for air to contact in flight, thereby minimizing or eliminating the tendency for the head to windplane. He tested his heads in a wind tunnel which was granted use by his friend Glenn Curtiss of aeronautic fame. The concave edge lent itself to increased penetration in game and Hill used this type of head and it's various prototypes throughout most of his hunting career. He figured out a way to put a hunting sharp edge on that steel, and he passed along his technique for others to emulate and from that time 'til this, that edge has been a bugaboo in the broadhead world. Back before we had all the cool gizmos to hold a broadhead perfectly on plane on a sharpening device, the arrow was held in the user's hand and the user stroked a file along the edge to set a bevel and got the bevel nice and thin and s
