Drill chipping (periphery, chisel edge)

?Likely causes

• Mounting runout is largeAgreed by 2+ makers^{[1][2][3][4][5][6]}
• Feed is large, or feed at breakthrough is largeAgreed by 2+ makers^{[1][2][4][5][3]}
• Insufficient workpiece clamping rigidity (tends to appear at breakthrough)Agreed by 2+ makers^[1][6][3]
• Wide chisel edge or poor entryAgreed by 2+ makers^[2][7][6]
• Clearance angle became larger from regrinding, or lip height is largeOne maker^[4][3]
• Interrupted cutting at breakthrough, pre-drilled holes, inclined surfaces, etc.Agreed by 2+ makers^[6][5]
• Chip clogging in deep holesOne maker^[4][3]

✓Fixes

Cutting conditions

• Reduce the feed, and reduce it further at entry and breakthroughAgreed by 2+ makers^[1][2][4][6]

Tool

• For reground drills, check the clearance angle and lip height. If a new drill chips, use a smaller clearance angle and a tougher gradeOne maker^[4]
• Check the edge honing (increase it if needed)Agreed by 2+ makers^[6][3]

Setup

• Reduce runoutAgreed by 2+ makers^[1][4][3][6]
• Increase clamping rigidityAgreed by 2+ makers^[6][3][1]
• Make the entry and breakthrough surfaces flatOne maker^[6]

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