Shortly after introducing mass produced chrome moly steel pitons to the climbing world, Yvon Chouinard began so see their effects. Especially on popular routes, small cracks that had once been protected by a thin lost arrow, now needed large angle pitons, or stacked angles, or even a bong! The thin cracks in the granite had become an ever growing gouge in the rock.
Chouinard turned to a natural form of protection to replace pitons, and that was the chockstone. Chockstones are stones that wedge in a vertical crack, and can be from the size of a quarter, to the size of a Subaru. Climbers sometimes used them for protection when they seemed solid, and when nothing else was available.
Using the principle of the chockstone, he created a hexagonal shaped artificial chockstone, made of aluminum. These could be carried on a hardware rack like pitons, placed without use of a hammer, and removed by un upward tug. They were set by a hard downward tug, after being placed in a crack that was generally smaller than the width of the hex. The harder they were pulled down, the more they jammed into the rock. US Patent 3,948,485 is for a device called an Irregular Hexagonal Mountaineering Chock, marketed as the Hexcentric, in various sizes.
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