More Making Model Rope

by John

I had noticed something a bit odd when making ropes on my homemade ropewalk. It appeared that the threads were lengthening at one stage. That should not happen.

So, I examined the Gutermann thread under a microscope… Gutermann is the brand recommended by most model ship authorities, or at least ones to which I subscribe. It has less fluffiness than other brands, and a nicer, smoother, slightly shinier appearance. It is also 4-5 times more expensive than other brands.

A single strand of Gutermann thread. Approx 0.22mm diameter. Polyester. Not totally free of loose fibres, but much better than other brands. Notice that the stand has 2 strands which have a Z or right hand twist.

Z twist is the most common twist of ropes, probably because hemp fibres have a natural right hand twist, and it was noted in sailing ship eras that ropes made with a Z twist were naturally slightly stronger.

When I examined my previous technique for operating the rope walk it was obvious that I was untwisting the Gutermann thread during the initial phase of model rope making.

So today I examined every step of the rope making under a microscope.

My cheap electronic microscope. Not the clearest picture, but the information is useful. The thread is 0.66mm diameter. Quiz. What is the twist of that rope?

That is a completed rope. Now to consider the stages of manufacturing a 3 strand rope, with 2 threads in each strand. ie. a 6 thread rope. We ignore the 2 strands which are now visible in the Gutermann thread, but we will take into account the Z twist which Gutermann puts into their thread strands.

So, I prepared the ropewalk by threading 3 hooks on the looper, with 2 strands on each hook. Pictured is 2 of the 6 threads. At the other end of the walk all 6 threads hooked around the single motorised twister hook. There are reversing switches at each end, which I intended to use for this learning exercise.

Then I turned on the looper, and I made sure that I was following the same Z twist so threads were not untwisted. I was aware that this was NOT what I had done previously. The threads showed no tendency to lengthen, but started to progressively shorten. I continued until they had shortened by 250mm (about 10% of the overall length of the ropewalk.

This is one of the 3 strands, showing the intial “looping” process. Note that this is a Z or right hand twist, the same as the Gutermann thread.

Then when the threads showed approximately a 45degree twist, the looper was turned off and the other end motor was turned on to combine the 3 looped threads. Note that this is an S or left hand twist.

An early stage in finishing the final twist.
Close to finished. I aim for 45 degrees.

The ends of the rope had a drop of CA glue to prevent unravelling. If the two twist directions are approximately balanced , when released the rope will not try to unravel. The grid marks in the photo are 0.5mm apart. The rope is 0.66mm diameter. The S (left hand) twist will not be visible at the scale. But it will be correct for the standing rigging on Constitution. If I continue to use only Gutermann thread however, ALL rigging, standing and running, will be left hand.

I bet that no-one notices.