Deburr. The removal of burrs or ridges of roughness from the edge of blanks or partially completed items caused by cutting or shaping tools. Deburring of blanks can be done by mechanical means, by tumbling a large quantity at once in a tumbling barrel filled with deburring compound, as abrasive, shot or ball bearings. Deburring of coinage blanks is also done by upsetting, a mechanical process. Any item that is finished, as most medals, are automatically deburred by the first step of finishing, an abrasive blasting. Hand deburring is done by grinding or chasing, this can even be done on finished pieces if necessary.

History of Deburring. One writer describing the operations at the Soho Mint (circa 1790) where Matthew Boulton had developed blanking from rolled sheets, stated that the blanks were put in cloth bags. Young boys, 12 to 14 years of age would shake the bags, causing the blanks to knock against each other. This would deburr the rough edges.

From this primitive method, it was a natural step to place the blanks in a barrel and rotate the barrel. This was done first with a manual crank, the motorized tumbling barrel was not created until the end of the 19th century.