Octagonal Bellows

edwood · Post by **edwood** » February 22nd, 2006, 9:41 am

Hi! I just discovered this fantastic forum

, I was looking for how to build an octagonal bellow like this ones http://www.pentaconsix.com/P6Bellows.htm

I'm doing a thesis about building a large format camera but I need to make this bellow and I have no idea how to find a diagram.
I usually do the normal square sided ones, but octagonal...

If someone can help I will be very thankful!

Yuri

wolf · Post by **wolf** » February 22nd, 2006, 10:19 am

My guess is that the basic folding procedure is the same (ie a series of reverse folds), but with different angles. For the square bellows, the reverse folds are at 45 degrees, but for octagonal ones, you'll want the reverse folds to be at 22.5 degrees (as measured from the pleat lines).

Here's a rough crease pattern (blue = valley, red = mountain, or the other way around, if you prefer). I haven't tested it yet, so you might need to tweak the distances to get what you want:

[img]http://img240.imageshack.us/img240/3351/bellows5zs.gif[/img]

You'll need around 8 repeating units to get the full octagon.

edwood · Post by **edwood** » February 22nd, 2006, 12:58 pm

thanks!

I'm going to try it, I'll let you know what comes out

edwood · Post by **edwood** » March 1st, 2006, 3:30 pm

I really have to thank you again Wolf, I did the bellow in the weekend and it works perfect with you diagram.
Now I want to make it pyramidal (keeping the octagonal shape), I think it's quite easy, just mattter of angles.

Well, I'll post a pic when I have the final product
(this forum will be cited in my thesis if it's not a problem)