| 摘要 |
The present invention provides a drill for making a dilled hole having a high circularity. The axial asymmetric edge drill has a chisel portion formed in the tip center so that the chisel portion center matches with the drill shaft center. At least one of the cutting edges is in an axial asymmetric position with another cutting edge across the drill shaft center. The outline of the edges of the drill forms a circular arc.
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