Twin Nib Eye Dropper For A Friend High School Teacher

[fountainbel]

Hi all you fountain pen makers !

Attached a few pictures for a "twin nib" eyedropper demonstrator i've made.

A friend asked me for a twin nib fountain pen , but having a larger ink capacity on one side and a smaller ink capacity on the other side.

Being a high school teacher he wanted to use the larger tank for normal writing and the smaller tank for home work corrections. using red ink.

I already had the idea for a " twin pen with adjustable ink reservoirs " for a long time , and here it is.

The white plug inside the barrel- equipped with two O rings- can be moved axially in the barrel bore, and positioned according preference.

Total ink capacity is 3.4ml, after screwing one of the nib units out one can push the plug in the middle, obtaining a 1.7ml ink on each side.

Or - accommodating for your specific ink consumption needs - one can push the plug deeper- as shown on the picture - obtaining 2.2 ml at the larger side and 1.2 ml at the smaller side.

Filling occurs using a syringe after screwing the Bock size 6 nib unit out, no need to screw the section out.

This is a long pen, my friend had given me a pouch in which the pen would fit, so aiming for the largest ink capacity I've made the pen just fitting in the pouch.

Double capped length is 155mm; single capped length 150 mm, cap diameter 15mm.

I don't plan in making more of these pens, so If the idea would appeal to you, feel free to use it !

Best regards, Francis

http://i62.photobucket.com/albums/h89/fountainbel/P1000775.jpg

http://i62.photobucket.com/albums/h89/fountainbel/P1000774.jpg

[ajoffe]

Very cool! This is great idea and the pen looks beautiful.

[inkstainedruth]

So, do you have to worry about one chamber leaking into the other? Especially if they're not "fixed"?

Ruth Morrisson aka inkstainedruth

[ChrisN]

Interesting idea. That would look pretty cool with some colorful ink in there!

[fountainbel]

So, do you have to worry about one chamber leaking into the other? Especially if they're not "fixed"?

Ruth Morrisson aka inkstainedruth

No worries at all, both O rings have a radial pretension of 0.2mm and will surely not leak

This makes the plug has some sliding restriction in the barrel, keeping it positively in its "set" position.

Francis

[rhr2010]

 

This is a great idea. How do you push the plug, with a little stick? Too bad that you won't offer those for the public.

[Brooks803]

Very cool! I'll have to give this a try.

[fountainbel]

 

 

This is a great idea. How do you push the plug, with a little stick? Too bad that you won't offer those for the public.

 

 

Yes,after screwing one of the nib units out one can use a 3- 4mm diameter stick to push the plug in the desired position.

Note that I've provided a drill point cavity on both sides of the plug, so the stick is easily centered.

Francis

[richardandtracy]

An interesting idea beautifully executed.

 

To be honest, it strikes me as a highly engineered solution to something that doesn't need an engineered solution of any sort. I doubt if there would be an issue with the ink capacity if the solid reservoir section were simply drilled to a fixed depth on either end.

A more interesting, though equally massively over-engineered, solution might have been to have two piston self fillers operated by two rings. I think it's possible if the piston operation ring is put at the bottom of each reservoir. Might need circlips or something similar to hold the pen together though and the reservoir body might have to be part of the ring.

[You may have gathered, but I am trying hard to learn a lesson that my colleagues try to drum into me regularly - it's 'KISS' or 'Keep it simple. Stupid' - unfortunately in this, I am not a good student.]

 

Regards,

 

Richard.

[fountainbel]

An interesting idea beautifully executed.

 

To be honest, it strikes me as a highly engineered solution to something that doesn't need an engineered solution of any sort. I doubt if there would be an issue with the ink capacity if the solid reservoir section were simply drilled to a fixed depth on either end.

A more interesting, though equally massively over-engineered, solution might have been to have two piston self fillers operated by two rings. I think it's possible if the piston operation ring is put at the bottom of each reservoir. Might need circlips or something similar to hold the pen together though and the reservoir body might have to be part of the ring.

[You may have gathered, but I am trying hard to learn a lesson that my colleagues try to drum into me regularly - it's 'KISS' or 'Keep it simple. Stupid' - unfortunately in this, I am not a good student.]

 

Regards,

 

Richard.

Thanks for your reaction Richard !

Allow me to comment on your remarks

Making two individual blind chambers is more complex as using a hole completely through, at least in my experience.

Polishing the bore for optimum transparency in the end part of a blind bore is very time consuming and frustrating.

And even better, I was able to use a standard cast plexiglas pipe, so no machining internally nor externally !

This is the mean reason why i've opted for mounting a dividing plug ,and one gets the adjustable ink chambers for free !

So making a barrel with adjustable ink chambers becomes in fact less time consuming as drilling/polishing blind holes on both sides

As for the double nib piston filler, I've already made one, see :

https://www.fountainpennetwork.com/forum/index.php/topic/252990-crazy-idea-but-what-the-heck-fun-to-make/

Over engineered ? Could be, but I like these challenges, and …. i never compromise for quality !

Francis

[Flounder]

To be honest, it strikes me as a highly engineered solution to something that doesn't need an engineered solution of any sort.

 

I think that's why I like this so much! Very cool.

[fountainbel]

 

I think that's why I like this so much! Very cool.

Hi Flounder

Thanks for your reaction !

I only curious, which design elements you find "over-engineered"?

Given the arguments i've given which prove that integrating the adjustable ink chamber plug is in fact simpler and easier to make compared in making 2 blind ink chambers. This is not clear to me...

Francis

[Flounder]

Hi Francis!

 

Reducing the need for machining or even internal polishing by using an adjustable gasket in a cast plexiglass barrel is an engineered ("skillfully arranged" solution to a manufacturing problem (make a twin nib pen with separate reservoirs of unequal capacity). The execution is simpler because of skillful contrivance, which is always cool!

[richardandtracy]

If ready polished tube was what you had available, then it would have been nuts not to use it, and the solution presented is an innovative way to separate the two sides from one another.

 

Regards,

 

Richard.