A surgical instrument includes a detachable tool assembly. The assembly includes a connection rod and a tool, such as a pair of jaws or an electrode. The instrument also includes a shaft operatively connected to a handle movable between operating positions and an ejected position. A tubular housing encloses the shaft and a collet. The collet is attached to the rod and movable between the positions. The fingers of the collet are flared apart in the ejected position but collapse to capture the connection rod in the operating positions. A tongue-and-groove arrangement provides a secondary coupling between the assembly and the housing when the handle is in the operating positions.
