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The Encyclopedia of Horology

Glossary · Trade

Broaching

Enlarging or truing a hole with a tapered, multi-faceted hand tool.

Explanation

Broaching enlarges or trues a hole with a tapered, faceted hand tool rotated and drawn through it. Watchmakers broach worn pivot holes before fitting a bush, and smooth broaches polish holes to size. Cutting broaches remove metal; smoothing broaches finish it — confusing the two is a beginner's error.