|Post is a part of a larger series (Folds):|
What is swivel fold is not easy to define, but I can try using a well-known example. In figure 1, a swivel fold is performed on a Preliminary fold with one of its flaps Squash Folded (figure 1).
That is the most basic example of the open swivel fold. There is, of course, a closed or inside swivel fold as well (figure 2).
Now that I have shown a classical swivel fold maybe a definition would be in order?
The swivel fold is a combination of folds where, while doing one fold, we are inevitably doing another one too. To better understand the definition lets analyse the first example once again. If you take a good look at figure 3A, it is easy to see that what we call a swivel fold is, in fact, two folds. First one is called the “leading fold” (marked in red), while the second one is called the “trailing fold” (marked in blue).
As you can see, if we try to fold the “leading fold”, it is necessary to fold the “trailing fold” as well. If we try to do it in reverse order (figure 3B), you will realise that we could easily fold the “trailing fold” on its own. Therefore, let me repeat; the swivel fold is a combination of two folds, where one, known as the “leading fold” while being performed necessarily trails another fold.
As you can see, the swivel fold is not that hard to perform. But why then is this manoeuvre classified as an advanced manoeuvre, one that is hard to carry out? Well, it is most likely because swivel folds can take many different forms. Many of the swivel folds you are about to encounter while doing origami are not even remotely similar to one I have just shown you. Nevertheless, all those folds are classified as swivel folds if they satisfy the definition that one fold is trailing another. As simple as that.
But, do not bother with the swivel fold too much. When you need one, it will present itself naturally.