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Thread: Measuring Flex with a scale

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    Senior Member azkid's Avatar
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    Default Measuring Flex with a scale

    Experiment: Is it possible, let alone practical, to quantify nib flex by measuring line width versus applied pressure?

    My hypothesis going in was yes. Based on my range of pens, the ones I would call more flexy are the ones that require less pressure to produce a thicker line.

    Why do I care? Because in the absence of measurement, personal experience, or comparison with known pens, there is no real way to know how flexy one pen is versus another.

    To conduct the experiment, I used a low-cost, accurate, readily available 300g digital scale to measure applied pressure. I chose the following test pens, listed in order of expected flexiness from least to greatest:

    • 19?? Esterbrook LJ, 2556 firm fine nib -- I feel it is not quite a nail, but awfully close
    • 1948 Parker "51", gold nib -- I can get some line variation but have to press "hard"
    • 1930's Sheaffer Balance Junior, gold nib -- it is springy and cushiony, with a little flex but not like the Wahl.
    • 1920's Wahl Ringtop -- flexy without a doubt!


    Rather than trying to use calipers, I also drew lines using the following:

    • 1.1mm mechanical pencil
    • 0.5mm mechanical pencil
    • Prismacolor Premier fine line markers, 0.005 - 0.08 mm


    I wrote lines on a small bit of Clairefontaine paper (and yes I zeroed the scale after placing the paper on it).



    The results were basically what I expected in terms of subjective, relative feel.



    Following this experiment, if someone were to measure flex of their pen, I can easily imagine how it flexes by comparing it to measurements of my own pens.
    Last edited by azkid; June 5th, 2018 at 03:24 PM.

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    Senior Member Pterodactylus's Avatar
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    Default Re: Measuring Flex with a scale

    I see no benefit in such measures.

    What is won if you know that nib writes 2,653 times broader if you apply 300g of downforce in a given horizontal angle A and a vertical angel B ?

    Writing with flex nibs is an emotional thing which requires experience.

    You know if a nib is a: nail, springy , semi-flex, flex, super flex/wet noodle by feeling it.
    You will know from your experience to stay in the safe area and not to torture or break the nib.
    This need experience and feeling, admitting that some might not be able to get the right feel for a flex nib no matter how hard they try.

    And to reduce flex nibs to a factor X (Write x times broader than without pressure when force A is applied) do not do justice to a flex nib.

    There are so many factors which influence how a nib feels, the factor x is only one of it (and maybe not even the most important one).

    Try and practice with many flex nibs and you will see that they will all feel/behave different even with a similar factor X.

    But with experience you will be able to categorize nibs based on your experience easily in nail, springy, semi-flex, flex, super flex.

    But you will also see that nibs in the same category still can feel completely different, as there is so much more than a factor X.

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    Default Re: Measuring Flex with a scale

    Why is there the wish to quantify and simplify everything with an easy measure?

    I can only say enjoy and feel it, not measure it, there is no easy answer to quantify it (also the reason why I not posted something in the similar thread of EOC).

    If the world would be so easy why do we write with FPˋs instead of ballpoints?
    Why are 5 pens not enough for everybody, a pen with a XF, F, M, B, BB?
    Should be sufficient as a pen with a F nib must be the same as any other pen with a F nib (leaving flex and special grinds out of the game) as it writes with the same line width..... isnˋt it?


    And beside all of this, at the end it‘s not the tool that counts (even I enjoy great tools), it‘s the person which uses the tool, it‘s the users penmanship, his skill and art to master the tool and produce amazing things with the tool.

    And more skilled users will always outperform less skilled users, no matter which tools are used.
    And there is only one way to improve, practice, practice and practice......

    By the way, you don‘t need a flex pen to practice flex writing, a pencil is a perfect tool to start.

    You can get quite a lot of line variation out of a pencil and learn the technique (without purchasing expensive pens or the risk of damaging something)

    Here is a really old pencil example I‘ve made years ago.


    Doodles_Response_02 by Ptero Pterodactylus, auf Flickr

    The next training step could be a flexible dip nib.

    A fool with a tool is still a fool....
    Last edited by Pterodactylus; June 5th, 2018 at 04:05 PM.

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    Default Re: Measuring Flex with a scale

    Azkid, I am impressed with your work and your results. Though two points will always suggest a straight line, those graphs with three relatively linear functions of line width / force are very encouraging for your thesis. We can quibble about interpretation of line width, and effect of feed variation, and grams being mass, not force but all of those really are quibbles that miss the point you are making. If the line width is actually pretty close to linear for most nibs, then the slope of those lines is a SINGLE number that represents flex. BRAVO!

    I hope you continue your work and let us know how it goes. I would like to see a minimum of three test widths per pen (four or five would be better). Also, maybe you could plots your subjective feel of the flex along with your graphs, just to see how those correspond also.

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    Default Re: Measuring Flex with a scale

    Oh, I am not dismissing Pterodactylus's objections either. I just really like numbers and physical tests. If they numbers work consistently, then there is no reason to ignore them.

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    Default Re: Measuring Flex with a scale

    Yes, pens are to be used, felt, enjoyed — but not all purchasers can try before they buy.

    Attempts to quantify flex arise in part from a desire to avoid the disappointment of getting a nib that was described as being flexier than it is. I don't chase flex, or measure it, but am always pleasantly surprised if I get it. Those that do chase flex online might welcome greater objectivity.

    David Nishimura demonstrated a similar scale-based approach in 2015 and even touched on the idea of using dip nibs as benchmarks (something EoC also discussed in another thread).

    Of course the problem is getting vendors to agree on a standard, which is why most proofs of concept go no further.

    I think both azkid and EoC should run with their ideas. What's the next step?

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    Default Re: Measuring Flex with a scale

    I actually think this is brilliant.

    Why is it important? Mostly to be used as a tool across sellers to gauge nib flexibility beyond subjective measurements. This would provide some form of physical metric against seller's peddling "flex" that requires significant force to achieve line variation. if one nib can do in 150g of pressure what another can do in 300g, then we have a true metric for comparison. No hearsay, no BS, no complete subjectivity, just data. Want to see how Noodler's flex nibs compare to FPR flex nibs? Or how they compare to vintage semi-flex, even? I'm not sure why every attempt at quantifying and standardizing flex gradients is met with such outward hostility (or "I don't see the point of this its stupid").

    I, for one, would love to see an objective test for no other reason than to shut down to often smug statements of "well, the flex is very nice, but it's definitely not vintage flex!"

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by AzJon View Post

    I, for one, would love to see an objective test for no other reason than to shut down to often smug statements of "well, the flex is very nice, but it's definitely not vintage flex!"
    I said that ... many times

    Only without the smugness. More often accompanied by a feeling of disappointment.
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    Default Re: Measuring Flex with a scale

    This lacks the time coordinate which is needed for assessing the equally important snap-back of the nib.

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by AzJon View Post
    I, for one, would love to see an objective test for no other reason than to shut down to often smug statements of "well, the flex is very nice, but it's definitely not vintage flex!"
    What I don't understand (and there may be a well known reason for this that I haven't stumbled upon yet), is why "vintage" flex isn't offered in modern nibs. There's obviously a demand for it.

    Personally, I'm quite happy with my rigid nibs thus far in my journey (ignorance is bliss, and all that), though maybe after playing around with dip pens a little more, I might get the taste for a more responsive nib. It does seem a little bizarre that some enterprising venture isn't offering this as retrofit options (or maybe they are, and I don't know that either).

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    Default Re: Measuring Flex with a scale

    Bobo?

    Bobo?

    Bobo?

    Has anyone seen Bobo?

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by chalkdust View Post
    Azkid, I am impressed with your work and your results. Though two points will always suggest a straight line, those graphs with three relatively linear functions of line width / force are very encouraging for your thesis. We can quibble about interpretation of line width, and effect of feed variation, and grams being mass, not force but all of those really are quibbles that miss the point you are making. If the line width is actually pretty close to linear for most nibs, then the slope of those lines is a SINGLE number that represents flex. BRAVO!

    I hope you continue your work and let us know how it goes. I would like to see a minimum of three test widths per pen (four or five would be better). Also, maybe you could plots your subjective feel of the flex along with your graphs, just to see how those correspond also.
    I kinda goofed on the two measurements and the units of mass instead of force. Rats. Typical me. :/

    Anyway, yeah I may test some more pens and add some data points. Certainly, I welcome others to try this themselves and post results.

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    Default Re: Measuring Flex with a scale

    Although it doesn't appeal to everyone, I understand the interest of quantifying things, and even more of the methods we devise to quantify things. I worked in electronics calibration for a number of years, and have also done some mechanical calibration. So I can appreciate the thought that went into this, even if I'm not sure that I would find it of practical use.

    Here's another thought; might it be possible to measure the smoothness of a nib? I just throw that out there, without any intention of pursuing it myself.
    "If a thing is worth doing, it is worth doing badly."
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    Default Re: Measuring Flex with a scale

    It's interesting that we are both trying to achieve some sort of similar outcome but using different methods.

    1. My idea is to provide a quick qualitative measure.

    2. Your idea is to provide a quantitative measure.

    Both are valid in my opinion. However, I do think that my idea is more likely to be adopted (though perhaps neither will be) due to its sheer simplicity, despite the lack of quantifiable numbers.

    Having said that, it is rather unlikely at this point that either approach will be met with other than frosty stares from the eBay sellers. In this respect it would be perhaps better to engage with well-known non-eBay sellers (like Deb or Ron for example) with a view to getting the ball rolling. If there is momentum it may well have an impact on the auction site.

    Bit of wishful thinking I suppose, but ideas have to start somewhere.


    Oh, and to answer an earlier criticism - though not directed specifically at me - the purpose of putting forward these ideas (for me at least) was absolutely because lots of us don't have the 'try before you buy' option. Having some kind of measure, even a rudimentary one, would really help.

    And no, we don't want Bo Bo's ridiculous hair-splitting categorisations of flexibility. Heaven forfend!

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by lsmith42 View Post
    Bobo?

    Bobo?

    Bobo?

    Has anyone seen Bobo?
    Last edited by Jon Szanto; June 5th, 2018 at 11:05 PM.
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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by Empty_of_Clouds View Post
    1. My idea is to provide a quick qualitative measure.

    2. Your idea is to provide a quantitative measure.

    Both are valid in my opinion.
    Absolutely. Once you select some reference pens I will of course find examples and measure them

    Having said that, it is rather unlikely at this point that either approach will be met with other than frosty stares from the eBay sellers.
    *Melodramatic gasp* Surely not! Why, these are the same eBay sellers that, when selling watches, insist on such precise horological terms as "keeps good time" and "runs". Yes, I am being sarcastic.

    Here's another idea. Assemble a database of nibs' flex, then sellers don't need to adopt anything yet buyers could still get a sense of what they are getting compared to pens they already own. The database could have qualitative comparisons or quantitative or both.

    Another question comes to mind: if we could rate pen flex on a qualitative scale, how many rating numbers would be useful to the buyer?

    Or put another way, do we need more granularity between full flex, semi-flex, and nail?

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by penwash View Post
    Quote Originally Posted by AzJon View Post

    I, for one, would love to see an objective test for no other reason than to shut down to often smug statements of "well, the flex is very nice, but it's definitely not vintage flex!"
    I said that ... many times

    Only without the smugness. More often accompanied by a feeling of disappointment.
    I do honestly wonder how often the sentiment is given earnestly and how often is a perception bias. For example, there was a study done recently taking top-tier modern violins and pitting them against a Stradivarius in a blinded play-off. At the end, elite violin players were unable to discern which was the Strad and which was the modern violin with the majority preferring the modern. I'm not saying that vintage isn't special, but that our perception may be colored a little too heavily by our initial expectation of performance before even putting pen to paper. Though, I will admit that this pertains more specifically to semi-flex than full-flex.

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by azkid View Post
    Quote Originally Posted by chalkdust View Post
    Azkid, I am impressed with your work and your results. Though two points will always suggest a straight line, those graphs with three relatively linear functions of line width / force are very encouraging for your thesis. We can quibble about interpretation of line width, and effect of feed variation, and grams being mass, not force but all of those really are quibbles that miss the point you are making. If the line width is actually pretty close to linear for most nibs, then the slope of those lines is a SINGLE number that represents flex. BRAVO!

    I hope you continue your work and let us know how it goes. I would like to see a minimum of three test widths per pen (four or five would be better). Also, maybe you could plots your subjective feel of the flex along with your graphs, just to see how those correspond also.
    I kinda goofed on the two measurements and the units of mass instead of force. Rats. Typical me. :/

    Anyway, yeah I may test some more pens and add some data points. Certainly, I welcome others to try this themselves and post results.
    And then you labeled the axis as pressure which is neither mass nor force .

    As soon as I read your thread title it struck me as something very easy which someone should have thought of long ago. For those wanting to compare flexibility it's an interesting chart to develop. In the end I think Ptero is correct in that flex writing is about pleasure more than how much the pen flexes. Still, for those wanting a semi-flex or a super-flex it would be nice to see where different pens / nibs fall on the chart as they set out in search of a writing implement.

    I have a small kitchen scale. I'll see what I can do with my pens to add data to your chart. One thought on the chart...you may not want to fit a linear curve through the data points. It suggests that pressing harder will flex further and get a wider line, but depending on the nib and feed that's not true. Either you run out of ink and "railroad" at maximum flex / feed, or you push too hard on a firm nib and ruin it. I wouldn't want a pen n00b assuming 1kg on your Esterbrook nail is going to get a 1mm line. It's going to get a bent nib instead.

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    Default Re: Measuring Flex with a scale

    Quote Originally Posted by AzJon View Post
    I do honestly wonder how often the sentiment is given earnestly and how often is a perception bias. For example, there was a study done recently taking top-tier modern violins and pitting them against a Stradivarius in a blinded play-off. At the end, elite violin players were unable to discern which was the Strad and which was the modern violin with the majority preferring the modern. I'm not saying that vintage isn't special, but that our perception may be colored a little too heavily by our initial expectation of performance before even putting pen to paper. Though, I will admit that this pertains more specifically to semi-flex than full-flex.
    Alright, let's follow your example then.

    This is the "Stradivarius" (except it's not even a good analogy because the nib of this pen had been rescued from a chewed-up small ringtop BHR that is unknown):



    Now show me the "modern violin" version of that writing above that we can't discern visually. And tell me which modern pen was used.

    Perception bias? Not for me, it's not.
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