Direction-Related Variations in Tensions

Is there such a thing as being able to tighten the tension when the machine is sewing going right-to-left or loosen it when the machine is going left-to-right? There seems to be a noticeable difference in tension when the machine sews going to the left from when it is going to the right.

Now here’s a mystery uncovered: rotating hooks are actually producing two different sorts of stitch depending on whether the machine is moving to the right or to the left.

Try this diverting demonstration:

  • Set up the machine to sew slowly in non-regulated mode.
  • Stand at the needle end of your machine with it threaded as usual and the stitch anchored in the right-hand edge of some piece of work.
  • Turn on the machine and let it make stitches as you move it off the cloth to your right for about 20 to 30 cm.
  • Turn it off and gather the threads to hold them in your right hand.
  • Turn it on again and move the machine back to your left.

You will find that the first movement gave you a simple twisted thread. The second movement, however, has produced a rolling hitch with little knotty bits that have to be pulled back up through the needle holes in the fabric. Run your fingers down the thread and feel the difference between one and the other.

This goes a long way to explaining the occasional thread breakage and why there are such obvious differences in stitch quality when sewing "with the hook" and "against the hook". And yes - I think a smart stitch regulating system could vary the tension depending on the direction of movement - it just hasn’t happened yet.