Trigger parts for an AR-15 are machined from stacks of 1/4-inch stock in a computer-controlled Electric Discharge Machining (EDM) center. The operator sets up the machine just before going home for the day, and by the next morning the parts are complete.
Stock material in bar form is stacked and drilled in this CNC machine. Once drilled, the stock can be cut to profile in an EDM machine—two machines, two set ups, several operations, producing dozens of identical parts.
This machine has 14 different tools performing separate operations on a given part. As each tool is rotated into position it indexes off a common point, and the computer operates the tool to precisely perform the operation.
With bowls and trays of parts in front of her, Cecilia Soto Rodriguez assembles each trigger package at the facility. The parts are so well-fit and identical she can put one together in less than a minute.