By Phil Krol
Many model builders who have reached the rigging stage on their models wish they had better cordage. Most have heard that a contraption called a ropewalk makes model rope, but have no idea where to begin. Let me assure you from my own experience that if you can build a ship model to the rigging stage, you can build a ropewalk. The obvious advantage of using one is that you can lay up (twist) high quality rope in all the necessary diameters to fully rig the model. While some ropewalks are very complex and require advanced machining skills, my approach keeps it as simple as possible without sacrificing functionality.
A ropewalk consists of three components:
As the strands twist, torsion builds up until they want to knot or break. The three strands come together at the narrow end of the topper and with the aid of the looper begin to spin in the opposite direction to relieve this stress and form the rope. During the rope making process, the topper moves toward the whorls as if it were motorized.
Traditional rope is made in three different styles:
The whorls are nothing more than a set of four gears that simultaneously twist the strands. The center or drive gear turns three gears spaced equidistantly around it. Their size and pitch aren’t important, since the gear train is built around the gears you find. I found 1-5/8" diameter nylon gears with a bronze bushing in a surplus store for 50 cents each.
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Figure 1 |
I laid out the gears on a rectangle of 3/8" tempered Masonite® 5" x 6-1/2" drilled four holes to press fit bronze bushings with 1/4" inside diameter. The gears were pinned to 1/4" brass shafts that slid into the bushings and were held in place by collars locked with setscrews. These are available in the parts bins of most hardware stores. The center drive gear shaft extends 2" beyond the collar so it can be connected to a motor (see Fig 7). |
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Figure 2 |
To attach and hold the strands to the whorls, I first counter bored the shafts on the three twist gears to take a 1/16" copper tube ¾" in length. Next, I drilled and tapped 3 holes for a 2-56 thumbscrew to hold the tubes in the shaft holes. |
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Figure 3 |
The topper is a cone shaped piece of wood 1 ½" long by 1 ¼" in diameter with three grooves to hold the strands spaced equidistance. The point is hollowed out a little to allow space for the rope to form. These dimensions are not critical and variants of this shape will perform as well. The topper is mounted on a rod which is inserted into a ¾" x ¾" piece of brass rod to give the assembly some heft. This was mounted on a 7/8" x 2 ¾" x 1/8" wood platform which was mounted on a pair of O gauge railroad trucks to make a facsimile of a flatcar with a topper on it. The sprung trucks were purchased as a pair for $3.50. |
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Figure 4 |
The flatcar topper assembly travels on O gauge track which is mounted on a 2" x 4". Mine is 10' long and half lapped at a track joint so it can be taken apart to facilitate storage. The 10' length produces finished rope about 7' long. I have yet to encounter a rigging situation where the 7' length was inadequate. However, you can make the bed longer or shorter, as you wish. |
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Figure 5 |
The looper is the spinning device the three strands are attached following the narrow end of the topper. Some advocate the use of a reversible motor to assist this process. However, I prefer using a quality ball bearing fishing swivel for the looper. This is a simple yet effective approach. As rope begins to form at the tip of the topper, the looper starts spinning and the topper starts moving on the track towards the whorls. You just stand there and watch with little to no help from you. |
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Figure 6 |
A variable counter weight should be used to tension the strands and the forming rope. The weight is attached to a cord on the end of the swivel and extends over the end of the bed to the floor. A pulley or sheave on the end for the cord is helpful or even a smooth groove for the cord to ride in. The amount of weight varies from ¼ oz. for small rope to 1 ½ oz. for heavier rope. As the rope forms, the strands get shorter pulling the weight off the floor to about one third the length of the bed. A counter weight attached to the flatcar to create some resistance to its travel is also needed. This varies from nothing for very small rope to about ½ oz. for heavier rope. Since this weight travels the entire length of the bed, a gaff was installed to compensate for the shorter distance to the floor. This works by placing the cord in a sheave at the base of the gaff, running it over a sheave at the extended end of the gaff and down to the floor. The flatcar travels along the bed pulling the weight and when it reaches the top of the gaff, you stop the motor and transfer the weight cord from the tip to the base of the gaff and restart the motor. |
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Figure 7 |
The gear train is mounted on the track bed in a dado cut for a press fit at the head of the track. The motor is mounted on an extension of the track bed past the gear train and connected to the drive gear shaft with a universal joint. |
The MotorMy initial drive motor was a 3/8" reversible drill mounted to the track bed with a couple of wedges and a web clamp. A functional universal joint was made with a piece of ¼" inside diameter heavy wall plastic tubing. One end was secured to the drive gear shaft with a small hose clamp. A dowel was inserted in the other end for the drill chuck to grasp. This functioned quite well for years and finally failed in the middle of a ropewalk demonstration at a club meeting. In the process of repairing this failure, I found a motor that could be wired with a reverse switch and installed a universal joint purchased from the catalog of Small Parts, Inc. The use of a rheostat to control motor speed is recommended. For heavy rope, the whorls should spin at a slow speed and for finer rope a much faster speed. General OperationStrands of feed stock material cut to the length of the track bed are attached to the whorls. To “load” the ropewalk, I insert a strand in the end of the copper tube, slip it into the shaft hole, and tighten the thumbscrew on each of the three shafts. Some may prefer using hooks on the whorls to attach the strands. These are carried to the end of the track bed and each strand is pulled tight to create equal tension on all three and tied into a knot. This is now attached to the looper (fishing swivel) and the counter weight placed on the floor. Equal tension on the strands is important so good quality rope will start forming with no waste. Unequal tension will cause defective rope to form for several inches or until the tension is automatically equalized on the strands. Problems with twisting can usually be reversed. If too much counter weight is used, the twisting can cause knotting or doubling up. The motor is reversed to untwist saving the setup. Practice and experimentation will quickly enhance operator skills allowing the production of high quality model rope. Feed Stock MaterialsVirtually any thread can be twisted into rope; however, some are more suitable than others. The thread should be smooth and free of fuzz. Linen, cotton, polyester, silk and fly tying threads all make nice rope. Once you become addicted to rope making, you look at thread wherever you may see it for the potential it may have on your ropewalk. You never know what the outcome will be until you try it. |
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Figure 8 |
There are many thread shops catering to bobbin lace makers that can be found on the Internet that carry a variety of threads in a full range of sizes. DMC and Anchor are two brands of Egyptian cotton tatting threads that are made in a range of 10 sizes starting with number 10 through 100 which is the thinnest. Three strands of 100 will lay up into rope measuring .020" in diameter which is 1" rope in 1:48 scale. Threads are sized by number and number of plies. A thread sized 80/2 has two plies and an 80/3 will have 3 plies and be a little heavier. However, there is no standard in the industry so threads with the same number can vary by manufacturer. |
Showing coils of finished rope in various diameters. The second coil in top row from left is cable laid, stained and was twisted in two stages. The smallest coil measures .010". Two balls of DMC thread in size 10 and 100. The other two are 80/2 and 100/3 threads. All of these are available from bobbin lace vendors on the internet. Some local needle point shops may have some of these threads. The coils at bottom right are futtock shrouds with seized hooks in thimbles and stained with Jocobean MinWax®.
When the rope is finished twisting, hardening is a process that sets the lay and removes any stresses remaining in the twist. This can be accomplished by continuing the twist at the looper end and then stretching the whole length. You will find the swivel will spin some more, and when this is repeated and all the spin is exhausted, the rope is hardened and will not unravel when removed from the setup.
Twisting your own rope is a gratifying experience and allows you to produce whatever diameter is called for in the rigging tables. Most rigging books have reference tables listing the block and rope size for virtually every line on a ship by tonnage and/or rating. Rope circumference is almost always used and must be converted to diameter for our purposes (circumference divided by Pi or C/3.1416 = diameter). The easiest way to measure your rope is to take a dowel and mark it with a ruler to show ¼ inch and ½ inch. Wind your finished rope within these marks and count the turns, thus ½ inch or .5 divided by 26 turns = .019". This method is actually more accurate than using a micrometer as there is no compression of the fibers between the anvils. It is good practice to measure everything you produce and document the thread and counter weights used to produce it. When you need more of that particular size, you can produce it without experimenting. Incrementing the number of strands using the same size thread will expand your possibilities. You can go to six, nine and twelve or more strands to vary the size. Once you gain some experience, you will be able to determine just about what it will take to produce a given size rope minimizing the number of runs to achieve your objective.
Finally, coloring your rope can be done with various dyes or stain. I use Minwax® stain. Jacobean is good for standing rigging as it resembles Stockholm tar. Fruitwood by itself or mixed with a little colonial maple is good for running rigging. I wind a coil around my fingers, grasp with a forceps and dip in the can of stain for a moment. Then blot with a cloth and hang to dry. Treating the rope with beeswax makes it more stable and supple.
I hope you have found this article and accompanying photographs helpful in getting you on your way to making your own cordage. Perhaps you will be motivated to tinker some more and develop a continuous feed mechanism and take up spool so a large quantity can be made on a single run. Should you be interested in the history of rope making, a good place to start is Chatham Dockyard in England.