John Montroll - Ideal Split

[DanDaMan]

As simple as it seems, I cannot seem to get steps 4 and 5 of Montroll's Ideal Split, found in Robert J. Lang's book, Origami Design Secrets, Mathematical Methods for an Ancient Art. Here is the diagram below. Can someone please help me?

[orion119net]

Step 4, you are swinging over the white triangle, and the smaller colored triangle gets folded up behind the white triangle, so teh end result is that the white side of the bigger triangle faces the back, and the smaller triangle is on top. Then in step 5, you lift the top layer of the smaller triangle and pull it upwards, which pulls out some paper from under the small triangle.

Does that help any? Or just add to the confusion?

[ahudson]

It'd also help if you were using a better scan, or the original There's a mountain crease in step 5 that isn't really visible on the picture you uploaded; also the arrows are hard to read.

orion119net, I think step 4 is more simply explained as a swivel-fold (diagrammed on page 27, figure 2.30 of the same book)

Step 5 is the same as step 3, but in mirror-image. I don't know why it's explained differently.

[InsomniacFolder]

I do this manoeuvre by first making the vertical valley fold along the edge of the white area, then pinch in the diagonal mountain fold along the edge of the dark point.
Now when you pinch and lay the point over to the left and flatten, the paper will naturally use the precreased valley and you can squash the base in to the position shown (It is as far as the paper will allow you to go).
The fold in the layers behind happens automatically as you squash the dark point in to place.
For Step 5, you just pull the excess paper out from where the white headed arrow is shown (a single layer) and smooth the excess upwards and flatten it to match the other side.