Experiments With Flex

[bobje]

Fascinating work. A Leonardt Principal paired with an FPR 6.3 feed, inserted into a modified Jowo holder with the tail cut off, so it only works with eyedroppers. That is truly a creative modification!

[ReadyFireAim]

...so it only works with eyedroppers.

Actually it's a "sac-dropper" (1/2 eyedropper 1/2 sac )

I cut off both ends of a standard cartridge and slide a Parker #51 sack over it.

It then friction fits into the section because it's cork shaped.

It stays in place surprisingly well.

 

I also have a "sac-verter" that plugs into the cartridge piercing protrusion like normal.

Sometimes I use the little surface tension ball and sometimes I don't.

I use the sac-verter for #5 (#2) creaper nibs because I don't go big & fast when using them like I do with the Zebra-G & Leonardt-P.

 

I'm having much better luck with a sac than a converter on my flex pens.

The push-pull piston converter on the Neponset & FPR Himalayan do seem to work well enough though.

 

I know...

I use a FPR nib in a Noodler's Neponset & a Noodler's nib in both FPR pens.

(My opinion is FPR makes a better #6 & Noodler's makes a better #5)

[bobje]

Bordeaux, very interesting, cutting off both ends of a standard cartridge, and then sliding a sac over that. The only way I've created bulb/sac fillers previously is by cutting off the tail end of a standard cartridge, then connecting the standard cartridge opening into the "cartridge-piercing protrusion" of the section. This method:

But with the method you're talking about -- cutting off both ends -- what kinds of sections does the "cork" of the bulb/sac converter fit into? It would be dependent on the inner diameter of the section. The method sounds great, because the additional sac would help with temperature variation, preventing eyedropper burping.

"I cut off both ends of a standard cartridge and slide a Parker #51 sack over it.

It then friction fits into the section because it's cork shaped.

It stays in place surprisingly well."

[ReadyFireAim]

The Leonardt died on me last night so that makes it 5 days of writing for the nib.

I'm going to try again with a new one because it was such a fantastic writing experience.

 

In its defense, I did abuse it quite badly.

[ReadyFireAim]

I'm making another sac-cartridge.

This one is going to be a sac-verter because I'm cutting off an old converter instead of a cartridge.

I've had some cracks forming in the cartridge ones that lead to leakage.

The converters are made from heavier plastic so I hope it will prevent that.

I put lengthwise scratches inside the converter to help break surface tension because I'm not going to use the little ball this time.

I slide the sac near to the end of the cut off converter and glue into place.

The red dot indicates where the ID of the section locates.

Here is a pic of my new one and the the one in the pen.

The silicone of the sac gets trapped between the converter and the section.

When I install it, I use a tiny bit of silicone to help it slide into place.

It is friction fit and has never fallen out on me...Yet

My last operation is deciding how big, if any, hole I want to make in the opening of my sac-verter.

I may not cut the end off at all if I want to plug it in like a cartridge.

Edited August 16, 2017 by Bordeaux146

[bobje]

Some similar approaches to creating a bulb filler here in a thread from 2011. In these cases also, the sac is shellacked to the inside of the section.

 

https://www.fountainpennetwork.com/forum/index.php/topic/199676-eyedropper-that-doesnt-burp/

[ReadyFireAim]

2 updates...

 

I got a week out of this Leonardt Principal after pulling & cleaning it every night

AND... It is still going.

 

Found a source for 6mm ebonite.

I'm going to try and make my own feeds now because I have a couple of ideas for improvements.

 

http://vermontfreehand.com/product/black-japanese-ebonite/?attribute_diameter=6mm&attribute_length=6%22

[Synnove]

Absolutely. Using scales to determine the flexibility of a nib has been unsuccessfully attempted for many years. While I applaud the effort for those propositions, their results have failed tremendously because they provided inaccurate measurements.

 

I wrote a long rebuttal but it was unfortunately eaten by the forum software.

 

Suffice to say, while I appreciate your desire to illuminate the complexities of the matter, I take offense to your besmirching my experiments and data collection methods, and also would like to point out you've made a lot of assumptions in regards to how the data I've presented was collected, as well as the conditions they were collected under.

 

 

This thing is very obviously more flexy than the Zebra-G and a lot less temperamental. (so far)

 

I'll be interested to see how long the plating will last exposed to ink.

If it lasts a week, I'm cleaning my other pens and putting them away.

 

It takes a lot less force splay the tines a given width on the LP than the ZG. I'd be willing to wager that a large part of this is due to the fact that the LP has a wide pressure relief hole in the middle. This has the effect of pushing the "pivot points" of the tines farther to sides, where they will spay "out". When the pivot points are located closer to the slit of the nib (via taking material away from the sides) the tines will splay "up", which results in a soft nib but not necessarily a flexible one.

Edited August 24, 2017 by Synnove

[Mauricio]

 

I wrote a long rebuttal but it was unfortunately eaten by the forum software.

 

Suffice to say, while I appreciate your desire to illuminate the complexities of the matter, I take offense to your besmirching my experiments and data collection methods, and also would like to point out you've made a lot of assumptions in regards to how the data I've presented was collected, as well as the conditions they were collected under.

 

 

 

Synnove,

 

I am afraid to tell you that I have not seem any of your experiments and data collection. I have not quoted you of your analysis either. I would be very interested in seeing your analysis. However, we cannot hijack this thread analyzing a secondary subject that is not the main subject discussed by the OP in this thread. Could you share your analysis with me back channel? Thanks

[Synnove]

??

In the post above yours that I referenced (post #78), the OP posted a link to a chart that displays my data, as well as a link to Nishimura's ideas... both of which reference using nibs on scales to correlate pressure applied with flexibility. Your post proceeded to impeach this method: "While I applaud the effort for those propositions, their results have failed tremendously because they provided inaccurate measurements." Whether you know it or not, meant to or not, you were trashing both my and Nishimura's work with your statements.

[Mauricio]

??

 

In the post above yours that I referenced (post #78), the OP posted a link to a chart that displays my data, as well as a link to Nishimura's ideas... both of which reference using nibs on scales to correlate pressure applied with flexibility. Your post proceeded to impeach this method: "While I applaud the effort for those propositions, their results have failed tremendously because they provided inaccurate measurements." Whether you know it or not, meant to or not, you were trashing both my and Nishimura's work with your statements.

 

 

Synnove,

 

As stated in my previous post, I have never seen any of your experiments and analysis. The link in post #78 only shows a chart you created. My comments in post #79 did not refer to your chart as a chart without the methodology to collect that data does not mean anything to me. My comments in that post referred to the methodologies used by others to quantify the degree of flexibility of a nib over the years and in various places in the internet. As a matter of fact, there are various threads here in FPN where I have thoroughly elaborated on the multiple flaws, assumptions and presumptions used by the different proponents of different methodologies to measure flexibility of a nib. I have never seen your proposed methodology.

 

Sorry if I offended you with my comments. Once again, I was not referring to your chart.

Edited August 25, 2017 by Mauricio

[bobje]

FPN contributors are so passionate and focused on the fascinating details of this hobby that we sometimes forget we're all on the same team. Flex seems to generate passionate debate. Hanlon's Razor helps in these instances ... no need to assume bad intentions when it's probably just misunderstanding.

 

Building on a previous observation from Synnove, I'm trying to think through the way the pivot points of individual tines function on a flex nib.

 

In this drawing of nib P1 and nib P2, TW1 and TW2 are the effective tine widths, and X1 and X2 are the approximate locations of the splay pivoting point, around which the tines splay horizontally. We're making a distinction here between "splay" and "spring", in which splay is the horizontal movement and spreading of the tines, thereby widening the slit/ink channel. Spring is the vertical movement, which creates a cushioning or shock absorber effect.

In nib P1, widening the vent hole narrows the effective width of the tine and pushes the pivot point of that tine outward, toward the shoulder. In nib P2, cutting a scallop into the shoulder narrows the effective width of the tine and pushes the pivot point of that tine inward, toward the vent hole.

This is the way I'm interpreting "splay pivot." Narrowing the effective width of the tines from different directions (either enlarged vent hole or narrower shoulders) would move the splay pivot point in different directions. I have no data to confirm accuracy. (The splotchy nature of my label "SPLAY PIVOT" on the drawing results from placing it on the scanner window before the ink dried. Darn fountain pens. )

 

[Synnove]

Your diagram is correct; taking material away from the sides moves the "pivot area" towards the slit, whereas taking material away from the center moves said area away from the slit. If you look at the breather holes of the Zebra G and the Leonardt Principal, you'll see those configurations respectively.

 

I've created a document that I hope will provide further clarity as to what I'm talking about: https://drive.google.com/open?id=0B_lLElMSrpIPYmpxRUx0ZE9kNHM

 

A few clarifications I forgot to include:

 

The area of the nib that undergoes deformation not only depends upon the geometry, but also depends how much material has been ground away; I've nibs that have material ground away all through the tine which results in the majority of the tine undergoing deformation, and I've others that have more material taken away from a certain spot, resulting in that area undergoing more deformation vs the rest of the tine. Basically, whether material has been completely or partially removed, the rule of thumb is that when material is removed more deformation will occur in that area since it offers less resistance.

[bobje]

Synnove's illustrations are so exciting that I'll post them as a JPG file within this thread. The Google Drive document is in much higher resolution.

 

[Pen Engineer]

Synnove's illustrations are so exciting that I'll post them as a JPG file within this thread. The Google Drive document is in much higher resolution.

 

completely agree, great explanation. The comparison of the nibs with the cut away sections and the wider breather hole is very good. One could add the influence of the nib radius (curvature) in the area of bending: the flatter the easier to bend. I would recommend my article on nib mechanics to increase the understanding of what is going on.

Ahm... I am not sure about the last note. Return of the tines depends on the modulus of elasticity and the geometry of the cross section around the bending area.

[bobje]

Results of using the same nib modifications on a Wing Sung 698 and 659, equipped with Pilot-style (non-flex) nibs, in this review of the Wing Sung 698.

 

https://www.fountainpennetwork.com/forum/topic/321365-wing-sung-698-piston-filler/?p=3908754

[Synnove]

Ahm... I am not sure about the last note. Return of the tines depends on the modulus of elasticity and the geometry of the cross section around the bending area.

Ah I wasn't meaning to imply that it's solely related to tine length, just that tine length is a factor (in concert with the variables you listed).

 

Assuming similar cross sectional geometry, and similar materials, the nib with longer tines should return to unflexed state faster. Assuming that the angle between the tines on both long and short tine'd nibs in this hypothetical closes at a similar radians/min rate when the force upon the tines is removed, and assuming that both nibs are flexed such that they both have the same distance between the tines, the nib with longer tines should complete the transition from flexed to unflexed since the angle between the tines on the long tine nib is less than the short tine nib.

[flummoxed]

Fascinating thread! It is always lovely to come back to FPN to read such threads.

[Pen Engineer]

 

Anyway. What I see being done is a reduction of the width and material in the tines. May I suggest that you try instead to reduce the thickness of the tines and leave the width as it is. That is really how flex came about, reduction of the thickness. This is best achieved by working directly on the nib. You could practice on a very inexpensive steel nib first. The Dremel will work well or you could try a fine stone used for sharpening knives.. Just be sure to constantly move the tool and do not "dig in" at any point. Start about one-half cm from the tip and continue to about one-third of the way below the breather hole (don't touch the area that needs it thickness to mount back in the housing of the pen properly). While teaching one of my great grandsons how to modify nibs (using my father's old equipment) we played successfully around with several nibs and did exactly what I have described. I should like to show you what I mean with pictures, but alas I am an Apple product user and I have had no success with posting pictures on this site.

You are absolutely correct and what you say follows the laws of physics. If you bend something its width effects the bending force and/or the distortion proportionally, the thickness effects it by the power of 3!

[Pen Engineer]

Bob, I'm excited about the progress you are making! Even if the process only results in some simple ways users can reliably modify these steel nibs to produce more flex that would be awesome. But I also find myself wondering if you might stumble onto something that could be produced at a manufacturer level, in other words a new nib design with feed combination that could be mass produced. Boy wouldn't it be something if it were possible to find a combination that would approximate vintage wet noodle flex in a modern steel nib pen for under $50! This all definitely makes me want to put my thinking cap back on about this possibility. Keep up the good work!

 

I think I'm about to head over to my desk and try out some of your mods and see what I can come up with myself.

 

Kevin

Fountain Pen Revolution

all I have seen so far... IMHO... does not present any challenges to mass production. Go right ahead