Well you can't help your Mark 2 Calibrated eyes....
The thing to think of is. are you going to be printing in tiny Japanese script mostly with the nib ?(EF western= @** F Japanese) Or writing the larger flowing cursive (F western =@** M Japanese).
Do you want to enjoy shading inks? Then F....and you can print with F....and often printing gives even more shading than cursive. F will be smoother.
**@......all nibs are only @......first there is the fact that every company has it's very own standards, based on their customer survey....from who knows when.
A company back in the old days of One Man, One Pen, & the corner pen shop; listened to it's customer and trained him to what they thought he wanted. Parker made a wider nib than Sheaffer. If Parker made narrower nibs that their customers could become confused and buy a Sheaffer. Same for Sheaffer making a wider nib.
Then there is the normal slop/tolerance.
Now we get into Slop/Tolerence....that even Japanese nibs have. Until there is 100% robots making nibs, there will always be variance.
Pinned over in the Sheaffer forum is a great article from Ron Zorn, who got to Sheaffer's Ft. Madison factory just as it closed.
He saw the nib tip measuring guage.
A Fat F could = a Skinny M exactly....depending on the mood of the man making the measurements.
Then you have next, a nib that was 1/100's of an inch closer in, and so on. Passing through the middle of Tolerance to the other edge.
From Ron Zorn:
Sheaffer used a dial indicator nib gauge for measuring nib sizes. The nib was inserted into the gauge, and the size read off of the dial. A given size being nibs that fell within a given range. What is listed below were the ranges given on a gauge that I saw in the Sheaffer service center prior to being closed in March 2008.
Measurements are in thousandths of an inch.
XXF = 0.010 - 0.013
XF = 0.013 - 0.018
F = 0.018 - 0.025
M = 0.025 - 0.031
Broad* = 0.031 - 0.050
Stub = 0.038 - 0.050
*there was some overlap on the gauge. May be 0.035 - 0.050.
Parker a bit fatter, Sheaffer a bit skinnier....and each and every company had and has it's very own standards, made from market surveyes back when that mattered. (Fat Sailor...skinny Pilot)
Even nibs 'marked 1.5 or 1.0 or what ever you want to mark them with....not that I have the slightest idea if a 0.5 is medium or fine....there will be slop there too. An "0.5 could be 0.6 or 0.4 and still be with in tolerance.
Unless you are at the shop checking out the widths of same marked nibs.....you have to take pot luck with your nib width......unless you want your nib ground to exactly your tolerance...which will be yours....not mine nor your friend. You can get a nib made skinnier easier than fatter.
Every nib can be with 1/2 it's width...and be in tolerance. Every company's F western or Japanese will be different.....
So to expect a nib to give you what you think that marking should be.....is wishful thinking. You can luck out or get a 'fatter nib'......and I find it always so 'funny' no one complains about a nib too thin your M that = an F. It's always a F that = a M.
With different companies, different era's....all I can think is those nibs are @broad, @medium, @fine and @ extra-fine....if that. Fatter, middling or skinny is about it....
If one thinks all nibs are 1/2 size or more off...when or when not comparing cross companies ....then it's not a problem.
Nibs are always only going to be horseshoe or hand grenade close....even if you take the very next pen off the assembly line in that 'size'.
There will be fat, middling and skinny to tolerance Sailor and Pilot nibs also....it is not a western phenomena. It is universal. With Pilot being on the whole thinner than Sailor which has it's very own standard.
Does the nib write well?....good. Put it in your wide, middling or skinny cup and don't 'sweat the small stuff'.
Edited by Bo Bo Olson, 09 November 2016 - 20:53.