The Origami Forum

I folded my first model from a crease pattern today. I folded Brian Chan's Dobsonfly from his website here . I started by folding it into fifths then divided that into a 40 by 40 grid. I then added the diagonals and collapsed it into the base. My first attempts were done with printer paper then I folded one from tissue foil. It is a very well designed model and can be posed in resting or flying positions. Here are a couple of pictures.

Resting Dobsonfly

Flying Dobsonfly

I quote another person, that made the question in the wrong thread:

T wrote: Just another crease pattern related question.

Most ppl's defenition of a crease pattern is the creases left on the paper once the model is completely unfolded. Yet, I dont understand whether this includes creases which have been made (or used in the folding process) but were not being folded on in the final product. So is there a trick to knowing which creases are for the final product and which were just used to help the model build up.

The only method ive been able to pull of reasonably succesfully is getting a pencil and runing it along all the edges of the model on the inside then out then trying to work out where al the creases being used are and sharpen the lines I drew.

Thanks very much for quick replies.

There are no written rules for the CP's. Some authors include some lines while others don't.

If all the creases that were necessary to do the model were included in the cp, the cp would be useless, for there would not be a way to decipher which creases would end up folded in the final model.

The common way to do the lines for a cp is just to print the ones that are necessary to get to the base, the intermediate creases that are used for references and such are left to the creativity of the folder. If you want you can also include some lines for some finishing but being careful that they don't complicate things beyond a point where the cp would be of no use.

Thanks

But is there an easy way to tell which creases are used only in the final product and ones that were intermediate creases?

This is a question I've asked myself many times. I'll will look into it, ask other people and I'll let you know.

You should only print the creases that are part of the structure of the model. Usually a crease pattern only gets up to the base, meaning all the flaps are of proper length and coming from where they are supposed to.

Shaping folds should not be included as they add an inordinate amountof complexity to the CP for something as simple as a pleat.

If you want, to make it easier for others to solve, you can put the creases that are necessary to fold the model in a different style or color...

As for how to figure out which ones are part of the model and which just help you get it...

If the model has a really simple structure you can just unfold it and look at it.(Lang's Shizuoka Cicada actually has a very simple structure)

The way I used to do it (now I just unfold-refold) was to take a complete base and run one marker along the edges (mountains), and a different colored one along the valleys. This gave me mountain-valley differentiation, and also eliminated all the non-structural creases.

Also, very often the necessary, but non-structural creases are really simple, like the model's line of symmetry.

Finally, another somewhat helpful thing is the this pair of (Kawasaki and Maekawa's) flat-foldable CP rules:

1. At every interior crease intersection, M-V =+/- 2.
2. The two sets of alternating angles must add up to 180˚.

Immediately following from these:

You will always have an even number of creases intersecting (unless it's on the edge of the square). And consequently you will have an even number of angles around the point of intersection.

These are rules for flat-foldabe CPs. The rules for 3-D CPs are different.

Thanks again now I just need to get some software that can let me draw one

I'll just add that enev thoguh my questions are aboout drawing cps im about to give the dobson fly, talked about above, a try. Ill see what I can do.

you all are way beyond me in CP's and the math behind it all. i think what i saw is sort of appropriate here relating to anyone that has major difficulty in CP's, which would be ME! for one. (lol)
i saw a california vanity/personalized license plate with the letters: "ucantcp" on it.(u cant cp) i had to chuckle thinking it would have been the perfect plate fo me, since i cant cp! i dont know what the plate really means, but it was cute. maybe they are a closet origamist? (kidding)
sincerely, dani (feels good to be back)

wolf wrote:Another useful thing would be a list of CPs available on the web.

Hi,

You can (sort of) do a search in the ODB for crease patterns. Where I can, I try to mark crease patterns by adding CP to the model name. Basically a search for CP should find a few. It should probably be a separate field. I'll get around to it one day

Dennis

While they use Dr. Robert's (Hahaha) impossible reference points, his website http://www.langorigami.com contains no less than 21 crease patterns. Of course these are even harder than folding his diagrams... His Dragonfly varileg isn't that tough though... (At PCOC 2003 I couldn't take part one of his class because I had my own to teach, so he gave me a CP, and said if I could complete it I could take part two. As an added bonus, because I had folded from CP instead of step-by-step, I had probably the cleanest model of the group. )

Brimstone wrote:There are no written rules for the CP's. Some authors include some lines while others don't.

That would be pretty difficult. A CP without lines

Friet wrote:That would be pretty difficult. A CP without lines

For sure
And also as challenging as Jeremy Shafer´s Invisible Duck.

Hahaha, that's awesome!

Back on topic, there are some lines like the simmetry line and the creases that define which side an inscribed bird base folds towards to, that most authors include in the first place (even though it is not folded in the final model) and forget on thew second case.