Ok, I see where you are coming from Nick. Apparently everyone doesn't make the inserts the same. When you talk about the mold being centered and I talk about the mold being centered, it appears we are talking about two different statements when we say the mold is centered.

It appears you must center the mold in the cylinder so that it is equal distance from the mold to the edge of the cylinder no matter where you measure it. In that case, yes the hole in the ball would be drilled to what the thumb pitch is supposed to be.

When Anne Marie Duggan makes my inserts, she simply inserts the mold into the cylinder as it came out of the ball so where the tip of the thumb is, isn't going to be in the center unless the pitches to begin with are 0-0. The tip of the thumb is going to be slanted to one side of the cylinder. It appears that the way you make your mold and the way she makes hers is different. When she inserts the mold in the cylinder, pours it, removes the mold, taps the insert from they cylinder and insert a pitch guage into the insert, it is the exact same as the thumb hole pitches in the ball, thus the hole in the ball is then drilled 0-0.
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"Whenever I feel the urge to exercise I lie down until the feeling passes away."

Brick