Abstract: A fixture for establishing stop surfaces against which a workpiece can be held to accurately locate it during robotic machine tool operations. The fixture includes a table surface having frusto-conical openings arranged in a preselected pattern to receive locator pins. Each locator pin has a frusto-conical base which automatically centers itself in the opening so that a robotic machine can insert the pins without having to first precisely align them with the openings. Each locator pin is locked in its opening by a releaseable slide mechanism which acts against the pin on opposite sides by wedging action to securely hold the pin down on the table.