t5956ws

Ropewalk Question

My question is simple to those folks who own and use ropewalks for their models.  I do not have a ropewalk. Before I purchase one I'd like to know what the ropewalk end product diameter will be. In other words if I use a string say .25mm in diameter what diameter string will the rope walk produce with a three and four spool walk?  

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Multiply the diameter of the string/line/thread times the number of strands you will be spinning..  i.e.. 4 x .25mm = 1mm.

Eddie likes this

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14 hours ago, Gregory said:

Multiply the diameter of the string/line/thread times the number of strands you will be spinning..  i.e.. 4 x .25mm = 1mm.

I'm afraid it's not quite that simple. This would only be true if the strands were laid side-by-side. In rope, however, the strands are twisted together, making the diameter of the rope less than the sum of the individual strands.

 

My home-made rope machine uses a weight on the ends of the strands to hold them in tension while twisting. I have found that I can slightly vary the diameter of the finished rope merely by changing the weight and even by changing the speed of the motor that twists the strands. Other styles of rope machines may create ropes of different diameters with the same thread that I use on my machine because they make rope in a different way. In the end, I think the only way to know is, once you acquire a machine, make sample ropes with the thread you intend to use so that if you ultimately need a 1mm rope, you will learn how many strands of what size thread you need to make that rope on that machine.

 

Cheers -

John

mtaylor, jud, neptune and 6 others like this

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Will add to John's comment to also use the same twist per inch on each strand of threads and the the same twist per inch of the laid up rope.

jud

Canute, mtaylor, donrobinson and 1 other like this

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It is true that the weight can affect the diameter of the rope but it is possible to optimize the weight to use. It is also possible to predict the rope diameter and it is also true that the rope machine used will affect the rope diameter. Knowing this, if I turn 2 different rope diameters, it will be possible to predict other values  on an hyperbola curve for the same rope in different numbers of ropes.

tableau câble ancre.jpg

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Look through 'dafi's' building log for his HMS VICTORY. He made a lot of experiments with different types of thread to arrive at calibrated ropes. The final thickness depends on many different factors, such as the compressibility of the material itself, its surface roughness, and in particular the amount of initial and secondary twisting you give it. In practice, you will need to experiment with the threads at your disposal.

hornet, Canute, Eddie and 5 others like this

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Wefalck is 100% correct. I built myself a powered rope walker a while ago and the only way to get the correct diameter is to experiment.  I keep a sample and written record of each rope I make for future reference. I use a lot of antique thread picked up at antique and collectable stores because I find that they are often better quality than modern threads.  I enjoy playing with my rope walk so this is no big chore. 

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