Interesting thread. I use flexible vintage dip pen nibs for calligraphy, and I would love to find a fountain pen nib that has the same qualities, but to date, I have not (and I have tried many different variations of flexible fountain pen nibs).
Theres a lot more to that dip pen nib posted at the start of the topic than the nib cuts. Steel dip nibs are made of a thinner, tempered steel than what I see in typical fountain pen nibs. Any kind of plating on a nib also reduces its flexibility. Flexible dip pen nibs have no tipping at all, unlike most fountain pen nibs, so it is possible to achieve extremely elegant and refined thin lines along with the flexed swells, along with the inevitable scratchiness. (Many examples of flexed fountain pen handwriting posted here, while lovely, do not exhibit the degree of line variation needed for certain forms of calligraphy.) The qualities that make a good flexible dip pen nib also make it prone to wear and rust, and when that happens, you throw it away and replace it with another, from your box of nibs.
I hope AAAndrew will weigh in, since his Steel Pen blog is a wonderful resource on the history of the steel pen nib, documenting the exacting and time-consuming manufacturing processes needed to shape, grind, and temper a good flexible nib.
Eusorph, I really hope that someone explores your suggestion, and I would certainly buy their successful product, but I believe that creating a fountain pen nib that is similar to that dip pen nib is much more complicated than two simple cuts and flexy magic happens.
Edited by Grayspoole, 09 May 2020 - 12:02.