Pardon 1-2 typos (it seems that I can not avoid them ) but I think the message is clear.

Well, just hit the edit button and go back and fix them

Seriously, I am a bit of a newby to flex nibs, but what you say rings absolutely true. I have had to sample about 20 flex nibs now to know what really works. It isn't always the most flexy - but these factors that you cite here. I will have to post some of my best.

John

In addition to what you have written, I think a good flex nib should have:

1. A linear relationship between force, and displacement of the tines, (that is both lateral and vertical displacement)

2. A high ratio of lateral to vertical displacement. A small vertical displacement of the tines, should be associated with a large lateral displacement of the tines.

(A typical modern 18K nib has a low lateral to vertical displacement ratio.
A large vertical displacement is associated with a small lateral displacement.)

3. A maximum of 58.5% gold.

Although I believe that in the everwhelming majority of the cases this will be the case for all nibs flex or not, I can not see the reason that non-linearity would be a problem.


Excellent point! I have a pen like this, and although one might enjoy writing regularly with it, having a large vertical displacement with moderate tine opening makes control difficult (I do not "know" when to stop pressing). I am not ready to proclaim that a small ratio of vertical deflection to tine opening is optimum but I am convinced that if it is large it makes achieving line width variation difficult. Thanks for bringing up this excellent point.

One note on your comment about soft 18K modern nibs. The ratio of vertical deflection to tine opening is defined by the nib geometry (not by the material).



Yes, 14K appears to be better than 18K although I am not convinced that we have examined all possible alloys to find the optimum. Because of this I am not ready to claimg that 14K is optimum (it could be 15K but with some "special" alloying addition.

An awesome primer on flex nibs!!

I understand that the ratio of vertical deflection to tine opening is defined by the nib geometry.

Another idea I had was that a cross section, across the shoulders of a flexible nib, should be semicircular.

Instead of being semicircular across the shoulders, modern nibs are generally flatter and wider there. Modern nibs usually have a large radius of curvature across the shoulders. My guess is that flattening the nib (across the shoulders), reduces the ratio of tine opening to vertical deflection.

Yes, the curvature plays a role. More curved more flex. Richard once mentioned the following experiment. Take a cardboard and cut it into a nib shape. Try to flex it flat and "rolled" to see the difference.

Blorgy, you might enjoy to read this old post and the discussion in that thread.

Antonios,

Very nice primer on this topic. You capture a lot of key aspects of flex which the average FP user is not aware of.

BTW, do I owe you a snail?

Regards - Kirk

No, I do

Thank you, Antonios. I shall read the thread you suggested. I made a mistake when I wrote "semicircular". (None of my flexible nibs are semicircular.) I realized today that "semicircular" was at best, an exaggeration.