#1 --> not enough bending amount, thought to be an effect of "spring-back" phenomenon.
#2 --> V-bending phenomenon @ skyblue dot, thought to be inevitable.
so far, #1, 2 was wrongly thought to be a consequential result of bending a springy sheet material.
increasing press pressure by 10x improved overall shape.
especially, improving #1 was vital, because when the nib is slitted, a deformation occurs that cause "V type" slitting.
distance of #3 & #4 decreased
#4 is especially important, because the nib has to match the feed.
additional bending procedure was needed to match the feed, in the past.
1) reduced V type slit
2) overall shape closely matching original design
3) improved shape @ #4, increasing production efficiency
4) overall slit width reduced to < 0.1mm, from heart hole to point
5) increased compression of the nib, increases overall springiness
6) increased compression of the nib, increases overall surface hardness