Chuck jaw grinding blocks

After many years of use, the jaws on a 3 jaw chuck can get worn. If, like in my case, they go bellmouthed, a rod in the chuck can still wobble around.
I made three possible devices to preload the jaws. They all work by engaging the tapered end of the jaws where they are parallel to the other jaws. Each device can be trapped in this area and clamped down on. This loads the scroll just like the jaws are on a real part, allowing you to grind the jaw tips concentric and straight.
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