In the previous research log (#1), the prototype was through hole nib type.
Today's prototyping focused on no hole nib type (blind hole)
compared to through hole type, no hole type seems to have following advantages:
1) various nib design is possible because one feed design is compatible with all of them.
2) since the feeder is located internally problem of angular feed alignment is gone.
3) feeder is completely protected from air.
4) feeder locking mechanism is simplified.
some disadvantages:
1) feeder is thinner so machining it is more difficult.
2) nib point is very far away from feeder (I tested with the prototype and it works, but the slit must be thin enough so ink transfer is well executed initially. once the flow reaches the end, there seems to be no flow related problems)
3) some may prefer the look of exposed feeder (but full metal look is pretty cool as well)
I'm leaned more towards blind hole type, because I can diversify nib design models.