Knot-tying head

A knot-tying head comprising:

• first body having a front face, a channel in the front face extending from one side of the first body to an opposite side of the first body, and a second face opposite to the front face and separated from the channel;
• a second body having a front face and an channel in the front face extending from one side of the second body to an opposite side of the first body, wherein the front face of the second body is configured to seat against the front face of the first body such that the channels of the first and second bodies form an opening configured to receive a piece;
• a conduit extending along a serpentine path through both of the first and second bodies and around the opening, wherein the conduit is continuous from an entrance opening in the second face to an exit opening in the second face;
• a groove extending along the serpentine path through both of the first and second bodies, wherein the groove extends from the conduit to the opening along the lengths of the conduit, and
• a slot in the second face and extending between the groove at the entrance opening of the conduit and the groove at the exit opening of the conduit;
• wherein a width of the conduit is greater than a width of the groove, and the width of the groove is greater than a width of a filament intended to move through the conduit.