Manually loading the barrel into the fixture, and then the fixture holds the barrel in position. After that, 3 drillings units drill the pinholes on each side at the same time. There is a row of pinholes on every 90 degrees of the barrels and 3 sides in total. There are 3 servo mechanisms with the drilling units. The pitch could be adjusted by the servo mechanism. Manually un-loading the finished barrel from the fixture.