Sewings / Connections

When you make a sewing to the right, you lose a twist.
From the diagram below:  there are two twists in the pair to be connected.
Joining to the right:  you pick up and pull through the closest thread to the pinhole you are joining to.
You thread the other bobbin through this loop.  You can see from the illustration that when this thread is pulled through, one of the twists will disappear and you are left with only one twist.
Joining to the left:  you pick up and pull through the closest thread to the pinhole you are joining to.
You thread the other bobbin through this loop.  This creates an extra twist and you end up with three twists.