A small, flat and elongated tool is provided, with a hook at its distal end, for inserting between stitches and sliding under the threads of a serged sewing seam. The tool, held between the thumb and finger of a user, is effective to grab the tail threads from the serger seam and to pull them back into the seam.

Embodiments of present disclosure relate to a robot and a method for adjusting sewn threads. The robot includes a robotic arm configured to hold an adjusting tool, and a controller configured to cause the adjusting tool to partially go across a thread section along a path defined between a bottom side of the thread section and an outer surface of an object. The sewn threads have a first end fixed to the object and a second end, a plural of stitches formed across a sewing zone on the object between the first end and the second end, and each stitch has the thread section including a top side and the opposite bottom side. Then the adjusting tool moves upward away from the outer surface so as to adjust pitches between the stitches.

A composite sewn part for use in a subsequent curing process, including: a first composite laminate; at least one stringer secured to the first composite laminate by stitches, the at least one stringer including a first stringer portion comprising a composite laminate and a second stringer portion comprising a composite laminate, which are sewn together to provide the at least one stringer, the first stringer portion having a flange portion that is sewn to the first composite laminate and a web that extends upwardly from the flange portion and the second stringer portion having a flange portion that is sewn to the first composite laminate and a web that extends upwardly from the flange portion of the second stringer portion; and a polymer reinforcement located between the first stringer portion and the second stringer portion or between the first composite laminate and the first stringer portion and the second stringer portion.