What is the recommended lip clearance angle for a twist drill?

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Multiple Choice

What is the recommended lip clearance angle for a twist drill?

Lip clearance angle is the relief behind the cutting edge that prevents the edge from rubbing on the workpiece as the drill enters material. For a twist drill, about 12 degrees is the standard value because it provides enough relief to reduce friction and heat buildup while keeping the cutting edge well supported. If the angle is too small, rubbing increases wear and can cause built-up edge; if it’s too large, the edge loses support, which can lead to chatter or poorer hole quality. In practice, 12 degrees offers a reliable balance for general-purpose drilling across common metals.

Lip clearance angle is the relief behind the cutting edge that prevents the edge from rubbing on the workpiece as the drill enters material. For a twist drill, about 12 degrees is the standard value because it provides enough relief to reduce friction and heat buildup while keeping the cutting edge well supported. If the angle is too small, rubbing increases wear and can cause built-up edge; if it’s too large, the edge loses support, which can lead to chatter or poorer hole quality. In practice, 12 degrees offers a reliable balance for general-purpose drilling across common metals.

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