By inspecting tearing down old bellows, I found out that ribs between inner and outer layers, are not fully cover the whole area inside, always one pair sides of the ribs have the point ends, and the other pair of sides shaped in trapezoid, and thus rows of triangle areas are actually two layers formed, what if outer or inner layer cracked? didn't 3 layers of structure make better protection? I wondered why, shouldn't these ribs cover completely for the best light proof?
Seeking for the answer, I searched many resources of bellows building, including one tiny article bought from Xbay as below (I regret to pay for it!)
In page 4 of it (total 11pages) did show the ribs are made in two shapes, one set in tip points, and the other set is not, but it did not tell you why. And by building bellows for more than 10 years, I can insure you, this article did little help.
Instructed by this article, bellows building needs an exact 3D dimension form, so all 3 layers- inner/ ribs/outer layer build around the form, but when paste the ribs, there are problems when meet the corner, so the compromise happens, two sides of ribs keep the shapes needed, that is, tip corners, but other two sides had to be cut into trapezoid, what a pity!
And the article did not reveal the fact that, for fitting these compromise, 3D dimension form actually can not be made in EXACT dimension of bellows!
Google the web, there are people hand build their bellows, and generously reveal their way of bellows building, but many of them followed the mass production way, although they are made in hand.
So I built my way of bellows building, NO compromise.
These bellows are for the most recent batch conversion, you can see there are ribs fully cover the bellows, no triangle areas, and this is one of a kind, dared I say, now in the world.