Bernette Airlock b64 - 3-Thread Rolled Hem; 3-Thread Picot Stitch

Sewing test
67
2020-09 EN 5040064.00A.04
3-thread rolled hem / 3-thread picot stitch
With a balanced stitch formation, the upper looper thread (blue) loops around the cutting edge.
The Lower Looper thread (red) lies straight along the needle thread on the wrong side of the stitch.
The Needle Thread (green) is identifiable on the right side of the stitch as a straight line and on the wrong
side of the stitch as points.
Stitch pattern Solution
The Looper Thread is too loose around the
fabric edge.
> Increase the Upper Looper Thread Tension
(blue).
> Increase the Cutting Width «CW».
> Shorten the Stitch Length «SL».
The fabric edge doesn't curl as intended.
> Increase the Cutting Width «CW».
> Increase the Upper Looper Thread Tension
(blue).
> Elongate the Stitch Length «SL».
The Upper Looper Thread is too tight around
the fabric edge.
> Reduce the Upper Looper Thread Tension
(blue).
> Shorten the Stitch Length «SL».
The Lower Looper Threads are not parallel to
the needle thread.
> Increase the Lower Looper Thread Tension
(red).
> Increase the Right Needle Thread Tension
(green).
The seam puckers, the Lower Looper Thread is
overstretched.
> Reduce the Lower Looper Thread Tension (red).
The needle thread forms loops on the wrong
side of the fabric.
> Increase the Right Needle Thread Tension
(green).
The seam puckers.
> Reduce the Lower Looper Thread Tension (red).
> Set the Differential Feed between 1 and 0.6
(Stretching).
> Increase the Right Needle Thread Tension
(green).
> Shorten the Stitch Length «SL».
Tab.5: Optimizing the stitch: 3-thread rolled hem / 3-thread picot stitch