metal rod running between them. Most hold three or four bobbins. The bobbin sits on the metal rod. Other lazy kates are built with devices that create an adjustable amount of tension, which adds control to how much string is unwound using a given amount of force. Some spinning wheels come with a built-in lazy kate. On a drop spindle, two-ply is created by placing the spools on a lazy kate, tying the ends together onto the drop spindle, holding equal lengths of singles together and dropping the spindle. The weight of the drop spindle, combined with the twist in the singles, causes the drop spindle to turn in the opposite direction that the singles were twisted in until the two singles are plied together. Chain plying Chain plying (also known as Navajo plying) consists of making large loops, similar to crocheting. Only one single is necessary, and if the single is already dyed, this technique allows it to be plied without changing the color scheme. The spinner first makes a loop on the end of the leader—the string left on the bobbin, which the new yarn is spun from—that is large enough to slip their hand through. They pull some of the working yarn through the loop. Then the spinner starts applying twist to the three plies, consisting of the two sides of the loop together with the yarn pulled through it. When the loop and the yarn are nearly fully plied together, a new loop of yarn is pulled through the initial loop, and spinning continues. This process is repeated until the yarn is all plied. This technique allows the spinner to try to match up thick and thin spots in the yarn, thus making for a smoother end product. Machined yarns Machines that ply yarn use the 'regular' method mentioned above. The main difference is that gears control the intake, making sure that the strands all have the same tension and the same length. Other than that, the process for plying is exactly the same as when hand done. Novelty yarns Many novelty yarns make use of special plying techniques to gain their special effects. By varying the tension in the strands, or the relative sizes of the strands, or many other factors different effects can be achieved. For example, when a soft, thick strand is plied against a tightly twisted thin strand, the resulting yarn spirals.