Worst Origami Fold?

[origami_8]

Oh, if you like maths this is the right site for you. It describes how to divide a square in n equal parts.

[wolf]

Those numbers look like (5/7, 2/7), but they're not, they are actually (1/sqrt(2),1-1/sqrt(2)).

For all practical purposes, that's good enough. Using a ruler, marked in mm, to measure off sevenths is slightly more accurate for 30 cm square paper, but the difference is insignificant, compared to the inaccuracies you get due to creasing and paper creep. Experimental error wins again!

[DavidW]

Curse those experimental errors!

[jojotoar]

I hate dividing paper into odd ratios!
I think it is the hardest thing to do!

[stinlin]

I haven't done enough sink models, but the few I've done I've enjoyed. The crimps though...Ugh. I can never get them to work right - I spend so much time on it, and eventually it just "works". Ewwwww.

[OrigamiGianluca]

Definitively "Repeat on the other side"

[OrigamiGianluca]

Those numbers look like (5/7, 2/7), but they're not, they are actually (1/sqrt(2),1-1/sqrt(2)).

For all practical purposes, that's good enough. Using a ruler, marked in mm, to measure off sevenths is slightly more accurate for 30 cm square paper, but the difference is insignificant, compared to the inaccuracies you get due to creasing and paper creep. Experimental error wins again!

The difference between 5/7 and 1/(sqrt(2)) is 0.0071, that it could seams very small, but even in a medium size sheet (for example 35cm = 350mm) it gives an error of 2.485mm.
Not so small.
Even less small if I'd need to use 7th division to reach 14, 21, 28, ect splits

[origami_8]

The exactly opposite is the case, the larger the division the smaller the error gets. Let's take it this way, what for do you need a division into 7? In most of the cases it will be to fold a boxpleated model. Boxpleating doesn't need to be very accurate at all. It doesn't matter if you are 2cm off on a 2m square. I tried an extreme example and cut off a whole 20% from one side of a square to fold a boxpleated model and succeeded non the less (so the dimensions of the rectangle where about 8:10). Taking in account that the paper also expands into the grain direction while folding it may be that your 30cm square expands more than three millimetres into one direction while folding, making the small inaccuracy you got through the division even more unimportant.

[OrigamiGianluca]

Well it is clear that paper is not thickless, nor undeformable, and even the best origamist introduces some errors during folding.
What I meant was that the error coming from using that splitting technique could be acceptable for some work, but not unimportant because in my opinion could be bigger than the folding error.

I think the opposite from you regarding box pleating and similar techniques, because if you start from a not correct sheet division you will bring to you that error that could also be magnified if added to a not precise folding.
I'm thinking mostly on tassellation now.

[Silverin]

"dividing the paper in odd ratios"

can't start some Lang models because of that -.-

[Morgan]

ive never enjoyed closed sinks very much... open sinks are ok, unless you have to dismantle the model a good way to acheive it...closed sinks always become wrinkly for me...and can never get that point down all the way while keeping all the layers even....alas no insects in my repetoir yet...... HOWEVER! repeat on the other side mean only one thing. You have just spent 2 hours trying to figure out how to do step 13-30, and now that it has been finally done, your hands shaking with anxiety you put down your model, and peer to the next step..."repeat" *sigh* but my vote is for closed sinks because it is usally closed sinks that must be repeated

[origami_8]

I love closed sinks. So far I know only two that are near to impossible (Brian Chan - Shore Crab Step 85, Marc Kirschenbaum - Fluffy Step 55) but all the others are fun to do. What I don't like that much are open sinks that go around multiple edges where you have to unfold nearly half of the model to do them and then need to refold it so that everything is in the right place...
Grids don't bother me at all as well as repeat steps. It is always funny to hear the synchronous sighs when I teach the Spinning top by Manpei Arai and come to the point "unfold completely".

[Jonnycakes]

Dividing into odd ratios is a piece of cake-the Haga theorem is your friend. Open sinks can be annoying, but I don't think they can be quite as bad as closed sinks. They can be time-consuming, but closed sinks have the potential to tear or wrinkle and ruin a model. Unsinks and wrap the paper around are the worst, though-Lang's ladybug from Insects II makes me want to curl up in a hole and die.

And Anna, here is another impossible closed sink for your list-the Fiddler Crab from Origami Sea Life.

[origami-artist-galen]

I think that closed sinks can be the toughest (I'm right with you on the fiddler crab Jonnycakes), However unsinks ( open and closed) are usually, they're just really hard, especially with foil, to perform cleanly. Honestly, I really don't mind dividing into odd angles and countless precreasing.

[Max]

I don't like the paper divison. I also don't like the grid precreasing of boxpleated models. In most cases those two things become one...