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Rigidity Index. A Simple Method To Evaluate The Flexibility Of A Nib.


22 replies to this topic

#1 Croma

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Posted 04 June 2015 - 08:16

Hello:

This a new method for evaluate the flexibility of a nib.

Regards.

 

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FLEXOLOGIA%20english%20para%20imagenes_P

 

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Tabla%20de%20datos%20medidos%20imagen_zp

 

 

 

The spanish version is avalaible here:

 

http://issuu.com/smc...a_spanish_v1.0_

 

Regards.

 



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#2 pavoni

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Posted 04 June 2015 - 13:11

Wow!  Many, many thanks for this most interesting post. 

 

Great timing for me personally as I am currently auditing my collection of mainly vintage pens.  As I am constantly looking for the type of fountain pen nib that would give me close to dip nib satisfaction (particularly my favourite...Leonardt Principal) my audit concentrates on categorising my nibs by flexibility. 

 

I will likely adopt this 'Rigidity Index' to grade my nibs.  Even without a proper controlled environment (hard surface, accurate scales, consistent application etc), at least I will have a system that improves on my current guessing.  If there are faults in my measuring to establish a nib's RI, at least they will be consistent faults and in any event, I am grading my pens for my use and my benefit, so your post is hugely useful to me.

 

Wow!  I can't wait to try this out.  Rather than use a ruler, I think I will mark out the 1mm gap template in advance.  Quite looking forward to seeing whether my current (horribly unstructured) methods of grading a nib's flexibility compares to this RI method. 

 

Great post Croma.  Many thanks for sharing.  You've made my day :thumbup:

 

Pavoni.



#3 Croma

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Posted 04 June 2015 - 16:22

Hello Pavoni:

It is a great pleasure for me read your kind comment. You are an important refrence for me and your work and your collection is an inspiration and a dream for me.

I am glad to be able to help you and other collectors.

This is the best reward for my.

Thank you very much.



#4 Bo Bo Olson

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Posted 04 June 2015 - 18:00

Hi, you seemed to have missed regular flex as a bench mark....between semi-rigid (semi-nail) like a P-75 or modern 400...and semi-flex like a 140.

 

That regular flex could/would be the '80's-97 400, or modern 200 nib.

 

There are of course in the '50-65 Pelikan nibs those that have more flex than semi-flex'; those with 'flexi'/maxi-semi-flex. Same with MB, Soennecken, Geha and so on.

 

Those Pelikan nibs were picked by the original buyer, who could decide which of those two flexes he wanted at the corner pen shop....so one can not be sure out side the Pelikan 140 or the Diamond nib of the Osmia that it is 'only' semi-flex.

 

 

I like seeing the difference between the two Osmia nibs one a regular semi-flex (diamond nib) and the other the Supra nib which is what I call 'flexi'/maxi-semi-flex.

 

You have defiantly done more work than I will ever do....thank you.


German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.

www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,

 

The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.

 

 

 


#5 Cepasaccus

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Posted 06 June 2015 - 13:43

Why reduce the flexibilty to five possible values? Nibs with 240 and 260g are not that different, but probably will get different prices when one has RI 1 and the other RI 2.

 

I would not feel comfortable to put a "pressure" of 700, 800, 900, 1000g to a nib as it might damage the nib. And I wonder how many nibs would be really damaged due to this test.

 

My favourite test is to draw lines on a scale. There you can press as hard or light as you believe the nib should be pressed at most. Then you have a minium and maximum line with and a "pressure" for this maximum line width. The test is also described somewhere in this forum.

 

Cepasaccus



#6 iiiiiii

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Posted 06 June 2015 - 15:19

Thank you Croma! Although I can't entirely agree with the scale because suddenly most of my nibs which I would call semi-flex fall into the 'flexible' category, your way of flex measuring is simple, neat and pretty. Certainly, I have found it extremely helpful when comparing my own pens.

 

Addressing Cepasaccus concerns, I think that applying the force of up to 1000 g seems relatively safe for most rigid nibs I own, but peronally I too wouldn't recommend going over 700-800 g when flexing seems to become unusuable for normal writing anyway.

 

The method seems quite appropriate for someone who knows what is acceptable for a nib and when to stop pushing the pen against the scales. It's worth to warn that for a particular nib the maximum force may be 150 g of weight applied only before the nib is gone.

 

I agree that there is a huge risk of final damage in the hands of someone relatively inexperienced who may not know what is safe or someone who regularly tries to flex even non-flexible nibs. Well, common sense is not that common.

 

I agree with Cepasaccus that it seems to have a lot of sens to measure the force needed to open the tines and later the one needed to achive the maximum line width. However, I haven't tried it yet and for me personally the 1mm tines separation method should provide enough information on what to expect from such graded nib.

 

The problem is that the 1 mm separation doesn't seem to work well with most soft and 'springy' nibs I tried, which can be relatively flexible but don't normally allow for line variation, for example 3776 SF or MB 252. In such cases, the magnitude of the force (weight) needed to open the tines would be more informative and safer.

 

Once again, thank you!



#7 Bo Bo Olson

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Posted 06 June 2015 - 22:21

""to measure the force needed to open the tines and later the one needed to archive the maximum line width."""  ****

 

 

A number of years ago, when I had only one wet noodle...I saw a thread or a post in a thread, where some fine poster had measured his 6-8 wet noodles.

I don't remember the numbers out side of pressure used to open the nibs....don't think he measured nib width spread.

I saw there that those super-flex nibs could easily be divided into Wet Noodle or the term I read from Oxonian/ John Sawboda(sp?) a Weak Kneed Wet Noodle.

 

In a super-flex spreads it's tines 4-5-6 or even 7X a light down stroke, and I had that Soennecken wet noodle...which was nice but no where near some Dip Pen nibs I had, did not consider that a Weak Kneed Wet Noodle.

I had other Superflex nibs that I called Easy Full Flex.  They were with in a system I use with just plain pressure...@ thumb wise....horseshoe or grenade range, of 1/2, 1/2, 1/2 etc.

 

If one had a true regular flex nib....normally semi-vintage or vintage, when well mashed the tines spread 3 X a light down stroke. (Semi-rigid/semi-nail don't spread the tines 3X normally only 2X. (A 'Springy' nib is it's own flex set, in it's  2X tine spread with a semi-flex bend...like the Falcon or a modern MB.))

Semi-flex took half that.

'Flexi'/maxi-semi-flex half of that or 1/4th the pressure needed to mash a regular flex to 3 X.

I have some 30 semi-flex and 15 'flexi'/maxi-semi-flex pens.

 

Superflex: (I don't chase superflex, in I'd have to learn how to write well.)

 

Easy Full Flex uses 1/2 of that 'Flexi'/maxi-semi-flex or 1/8th of a well mashed regular flex. I've a good number of Degussa nibs in this flex, a 100N,, and a couple of others.

 

Wet Noodle, 1/2 of that or 1/16 of the mashed regular flex.

A Weak Kneed Wet Noodle would be less than that. I don't have one.

I do have Hunt 99-100-101 that make a Wet noodle look like it was not cooked.

 

Mauricio does not favor my simplistic approach. He though specializes in Superflex nibs and setting them perfectly.

I have a superflex Waterman 52 from him.

 

At first I was disappointed, it it appeared to be only an Easy Full Flex. However, half way through the tine spread test, it suddenly turned into a Wet Noodle. The pressure needed to spread the tines dropped by 1/2.

With Mauricio's vast experience my system when applied to super flex is a bit to simple to those who have many......especially when some superflex nibs have a varied flex rate.

That would become more time consuming to make sure the superflex nib being measured on a scale does not have such a varied rate.

 

I think my system sort of works for them who have worked their way up the flex ladder, one flex rate at a time...enough to give an idea with the scale.....of course I didn't have such scale when I started with my system. I wasn't going to waste pen of the week or ink of the month money on a scale, I didn't need.

Well after years and years my wife finally needed such a scale..her mechanical one was not exact enough and it was on sale.....and I'm too lazy to do a gram, 1/4th gram test.

 

The problem with my system is first one needs a true regular flex, simi/or vintage (or a 200).....not the modern semi-nail that is now being passed off as regular flex....modern post '97 Pelikan 400/600 are such semi-nails.

Then one needs a semi-flex like a 140....after that the system is simple. :headsmack: :doh:

It's close enough for horseshoes. :rolleyes:


German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.

www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,

 

The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.

 

 

 


#8 Tootles

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Posted 06 June 2015 - 22:46

After using a (very) few flex/semi-flex nibs on fountain pens, and more flexible dip nibs, I have to draw the conclusion that I have an exceptionally light hand. None of my dip nibs - typically Hunt 101, Gillot 303 and Hiro 41 - flex at all during normal writing. In other words I have to apply noticeable pressure to achieve swells. The thought of putting 700-1000g of pressure on a nib is astonishing to me.

 

So these discussions confuse me a lot because they imply that the way I write - from a pressure perspective - is incorrect, and that I should be bearing down on that bad old nib as if it was a ballpoint. That's okay though. I don't mind being wrong. I like the light handed way I write. It is stress free in ever sense!



#9 Goudy

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Posted 06 June 2015 - 23:19

A similar method was proposed in this YouTube video, though the poster there was suggesting measuring the pressure needed for the maximum line width a nib could achieve (not a particularly reliable method since different people would have different ideas about how far they can push the same nib). What's interesting, though, is that even though that experimenter seems to be pushing his nibs quite hard and getting maximum widths between 2-3mm, he never goes above 300g pressure. Like Cardboard_Tube, I'm a bit alarmed at some of the pressures being exerted in the tests recorded above (almost 1.5kg for one pen!).

 

 


utQ9Ep9.jpg


#10 Cepasaccus

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Posted 07 June 2015 - 23:43

To get the full advantage of flex nibs the pressure has to be controlled. Just scribbling might give some variations, but that depends on the writing style. Nibs with a "pressure" of around 200-250g as measured like in the video I find most comfortable even for scribbling. Nibs with over 450/500g I find to hard for all kinds of flexing. I have a feeling when the nib doesn't want to flex more. Obviously this is subjective.

 

Of course for scribbling you do not have to do maximum flex. If you go with 100g from EF to 1mm it is ok, also for controlled pressure nice writing.

 

Cepasaccus



#11 Mick70RR

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Posted 08 June 2015 - 20:16

I have four Mabie Todd Swans and I tried them on a set of scales as the OP described. One of them is very flexible, less than 200g for 1mm tine spread, and the other three are flexible, between 250 and 500g for 1mm tine spread. I must write with a light hand too because I would have put the first as flexible and the other three as semi-flexible. I find it difficult to write with the one without flexing the nib but the other three I rarely flex, I just get a wetter line here and there to give the writing some shading.



#12 Tootles

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Posted 08 June 2015 - 20:32

Good!  I am beginning to suspect that in many of the 'flex' videos the users are exerting far more pressure on the nibs than they were designed for.



#13 Cepasaccus

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Posted 08 June 2015 - 21:19

There are incentives to press harder than appropriate in demonstrations and writing samples, i.e. showing off and increased sales prices.

 

The attached writing sample is with a Waterman's No. 2 nib. That is probably about the maximum a Waterman's No. 2 nib can deliver. I have one which requires about 10% less force, but that's all the difference. (I have seen much more lighter flexible nibs of No. 4.) Minimum line width is 0.2mm, maximum 2.6mm at 350g. My feeling is, that this nib does not want to spread more than the 2.6mm. That 2.6mm is rather well reproducible by me. A rating with the method proposed here is around 150g.

 

Cepasaccus

Attached Images

  • writing_sample.jpg

Edited by Cepasaccus, 08 June 2015 - 21:19.


#14 manolo

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Posted 16 June 2015 - 06:57

It is a very interesting work on a difficult subject, thank you, Croma.

 

I understand that all those pens you tried can write a 1 mm flex line without their feed running out of ink, i.e., without drawing "rails".

 

Somehow you don't take into account the maximum spread of the particular nibs. For example, some nibs might open up to 2 mm, not only 1 mm, and that could be important for the "flex lover". Of course, it would be difficult to decide which is the maximum spread, as you would always have a risk of damaging the nib. I wonder if a parameter like RI=Force (grams)/Maximum Spread(mm) could be calculated and of any use.

 

Also, I figure that the Force vs Spread curve is not a straight line, as someone has already pointed out in this thread.

 

I am not into flex nibs, since I decided some time ago that I haven't got the skills nor the patience to write using flex (I favour stubs and obliques to get line variation), but I have read the report with interest. Thank you again.



#15 Croma

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Posted 04 July 2015 - 10:06

Hello:
I wish give thanks to David Nishimura. I am glad that "Vintage Pens" are interested in this method. The development of an auxiliary element to facilitate the measures is a great idea and it is on his blog.
(http://vintagepensbl...lexibility.html)
I think that Mr. David Nishimura have perfectly captured my idea: a simple, intuitive and objective method.
Thank you and good luck.
Best regards,
Salvador.



#16 Vintagepens

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Posted 04 July 2015 - 17:17

Thanks to you, Salvador.

I am only trying to build on your work, as I hope others will build on mine.

 

all best wishes

 

David



#17 pajaro

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Posted 07 July 2015 - 01:37

How frequently do users of flexible nibs bend the nib or flex it to the point where there's some loss of function?  I have a few pens with these nibs, but I never use them anymore, because I think I will ruin them.  Will this index help avoid overflexing?


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#18 Vintagepens

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Posted 07 July 2015 - 03:30

This index is intended only to measure a nib's resistance to bending. It is not intended to measure how far a nib may be bent without deformation or elevated risk of fatigue.

#19 christof

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Posted 07 July 2015 - 04:27

I believe, having seen a picture of a vintage tool, for measuring the flexibility of nib tines, somewhere in the past. The tool belongs to a friend. I will ask him to post a picture here. As far as I can remember, the function was quite similar as described here.
C.
What's Up At Christof's: http://www.fountainp...tofs/?p=2337615

 

fpn_1501079397__18762338330_19cf666a48_o


#20 Bo Bo Olson

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Posted 13 July 2015 - 20:59

Thomas (Kaweco) has such a tool.


German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.

www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,

 

The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.

 

 

 




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