| 摘要 |
A finger hole in a bowling ball is contour-drilled by mounting a bowling ball on a carriage and moving the carriage along rails toward the drill which has a larger cutting head than shank. After the first portion of the bore is completed, carriage motion causes it to engage a template which moves it on a second path to further drill the hole in another direction. The drill can be angularly positioned to provide shank clearance and can be positioned so that the drilling is other than radial of the ball.
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