Bernette b68 AIRLOCK - 3-Thread Narrow Seam; 3-Thread Rolled Hem

Sewing Test
80
2022-05 EN 50400685.00A.04
Stitch Formation Measures
The seam puckers. Lower looper
thread (red) too tight.
> Reduce LL-thread tension (red).
Needle thread (green) doesn't reach
the fabric edge.
> Reduce RN-thread tension (green).
> Increase UL-thread tension (blue).
> Increase LL-thread tension (red).
Needle thread (green) extends over
the fabric edge to the top.
> Reduce UL-thread tension (blue).
> Increase RN-thread tension (green).
The fabric edge forms a tunnel or
curls.
> Reduce RN-thread tension (green).
> Reduce UL-thread tension (blue).
> Increase the mtc micro thread control.
> Reduce the cutting width CW.
> Check the rolled hem selection N/R position.
3-Thread Narrow Seam
Stitch Formation Measures
Looper threads (red/blue) form
loops on the bottom side of fabric.
> Reduce LL-thread tension (red).
> Increase UL-thread tension (blue).
Looper threads (red/blue) form
loops on the top side of fabric.
> Reduce UL-thread tension (blue).
> Increase LL-thread tension (red).
Needle thread (green) forms loops
on bottom side of the fabric.
> Increase RN-thread tension (green).
The fabric edge doesn't curl as
intended.
> Increase the cutting width CW.
> Increase LL-thread tension (red).
> Increase UL-thread tension (blue).
> Reduce the stitch length SL.
> Check the rolled hem selection N/R position.
The seam puckers.
> Set the differential feed between 1 and 0.6 (stretching).
> Reduce RN-thread tension (green).
> Reduce the stitch length SL.
3-Thread Rolled Hem
Stitch Formation Measures
Upper looper thread (blue) wraps
fabric edge too loosely.
> Increase UL-thread tension (blue).
> Increase the cutting width CW.
> Increase the stitch length SL.