The Origami Forum

This is probably a stupid question, but: is there a way, other than eye-balling it, to divide the diagonal of a square into thirds? I've seen plenty of great techniques for dividing a horizontal into thirds, fifths, etc., but nothing similar for the diagonal. Has anyone developed similar fold-only techniques for this?

I use the normal 3rd method of connecting a corner with a 1/2 pinch mark where it crosses the other diagonal is 1/3

hmm, im interested to kno as well. Will you give us more explanation Trouble? =)

In the last pic, the upper left corner is 30 degrees/60 degrees. You only have to fold the right part of the angle in half to get a trisected angle.

Maybe Reference Finder is something for you (requires some knowledge about math for the more complex references)

Edit* : Hmm just noticed that this might not answer your question :\. Though dividing the diagonal into thirds is the same as dividing the square into thirds as far as I know.

solved it picture on my flickr

Interesting! I was in the process of making Kawahata's Stegosaurus, and the first step is to divide a diagonal in thirds. I was wondering how to do it without making the horizontal one-third creases first because the model doesn't call for them otherwise. I was just curious if anyone had worked out a similar system of pinching landmarks for a diagonal as well as a horizontal. Of course, I could have used the horizontal pinch system and them made additional pinches for the diagonal, but was curious if there was another way. Thanks, all!

Fujimoto's approximation method would also work. You wouldn't need marks on the sides, but you'd probably have a few extra marks on the diagonal near the correct location.

http://www.envelooponline.com/nan/archi ... explained/

Does anyone know how to do this with fifths?

one could do this forever, really. purism is overrated. just use a protractor and ruler. dr. lang himself does.