The Origami Forum

I need help with tripartite pleats or dividing an angle into three. Please give me some tips. I can't do the Unicorn and the Barosaurus (both by Kamiya) because of that crappy tripartite pleat.

Please, I need help

Well, ive folded neither of those models yet, but you do need to fold the 1/3rd pleats in both the ancient dragon and bahamut, which i have folded. In those models i just used an old fashioned ruler and scored the 1/3rd and 2/3rd marks along the paper, and then folded the pleats along the marks. I dont know if that helps, but its one way of doing it, without creating extraneous creases, and its very accurate if you do it carefully.

I've never had a problem guestimating. Just pinch the point and slide the edges along until they meet the folds.

here we go

Ummm..... I think he meant parrallel pleats, and on a small portion of the model, not the whole square. Anyway, I reckon guesstimating works fine.

Chris, this ruler is absolutely useless for trisecting an angle. A set square could help, but I would just guess that's easier and most of the time accurate enough.

oh whoops

The Haga Theorem is your friend-you can use this to divide the paper into nths, where n is any positive integer.

Just estimate-- in step 12 of the Barosaurus, Kamiya shows a good way to do this. It's not mathematically precise, but it's close enough for both of these models.

Haga's theorem, fujimoto approximations, and other constructions aren't much help in this situation, because you need to create long pleats that are close together. Estimation is the only method that makes sense.

Ragnorax wrote:In those models i just used an old fashioned ruler and scored the 1/3rd and 2/3rd marks along the paper, and then folded the pleats along the marks.

I'm using this method. Hmmm . . . But i don't bring a ruler at all times, so I'm having difficulty with that one . . .

Here's a tutorial on how to divide the paper into thirds by our kind friend Stephen O Hanlon
Here is the url,
http://www.fishgoth.com/origami/diagrams/division.pdf

Chris, this ruler is absolutely useless for trisecting an angle.

ok, let me be more precise

Gosh you get fancy geometrical Instruments in Germany!
The Protractor/Set Square Combo - you'd have to special order that here.
Far more practical than our rounded versions.

specialorder... really? that kind of ruler is pretty cheap here, less than 2 Euros. I thought it is available everywhere