The boy mechanic, book 3

by Unknown

Countersinking a Hole Smoothly

When a hole in a piece of steel, iron, or brass is being countersunk, the drill usually chatters, making the countersink rough. Where a smooth hole is required, it is best to make the countersink first and drill the hole afterward. By doing so the hole will be perfectly smooth.—Contributed by Chas. G. England, Washington, Pa.