Eye Dropper Design

[TDahl]

Greetings everyone,

I have been researching information on fountain pen Eye Dropper designs and have not found a source of comprehensive designs and/or information on making a dedicated Eye Dropper fountain pen. I have been able to collect bits and pieces of information most of which had covered converting fountain pens designed to use converters/cartridges into Eye Dropper systems. I created a dedicated Eye Dropper design that uses two "O" rings at the shoulders of both the section and the nib housing. I plan on using "O" ring silicone grease around the threads of both the section and the nib housing to ensure I have a good seal. I also plan on cutting a small funnel shape in the tenon of the section that will lead to a small channel that is the same diameter of the nipple of the nib housing to help with ink flow.

I attached a photo of my sketch design to not only share my idea with everyone who wants to explore creating an Eye Dropper pen, but more importantly get feedback and constructive criticism from those more experienced with this type of filling system.

Thanks for looking.

Tim

 

[hooked]

I am heading toward trying this myself when I have some time to experiment. I had the same plan with the O-rings, silicone grease, and ensuring my threads are tight. I am curious how the funnel shape will help with ink flow. It is a cool idea. Please post your results.

In one of the As the Pen Turns podcast episodes, Jonathon Brooks discusses how he drills a tiny hole in the nib housing at the top to improve ink flow. They touch on it at the beginning of episode 31 if you want to check it out. In an earlier episode, he goes into more detail, but I can't remember which one.

 

[d_bondi]

I am heading toward trying this myself when I have some time to experiment. I had the same plan with the O-rings, silicone grease, and ensuring my threads are tight. I am curious how the funnel shape will help with ink flow. It is a cool idea. Please post your results.

In one of the As the Pen Turns podcast episodes, Jonathon Brooks discusses how he drills a tiny hole in the nib housing at the top to improve ink flow. They touch on it at the beginning of episode 31 if you want to check it out. In an earlier episode, he goes into more detail, but I can't remember which one.

I recall that same discussion on the As the Pen Turns podcast, but I also don't remember which episode. I do remember that Jonathon Brooks noted he uses micro drill bits from Harbor Freight.

They also talked about chamfering the inside of the section tenon so that the square edge doesn't create too much surface tension resistance to the ink flowing into the nib. I think the takeaway there is in your drawing the "funnel" chamfer needs to be larger at the barrel end so that there is no resistance to the ink flowing into the section and nib. I hope this makes sense.

For what it's worth, from same source (ATPT podcast) Jason does use o-rings, but I don't recall Jonathon saying that he does, I think perhaps he has tight enough tolerances that just using silicone grease is good enough. Brad notes that whatever you do, you should test the pen by filling it with water first and if it holds water, then try it with ink.

 

[PatrickR]

following along, although I don't plan on making an eye dropper.
I'm not following why the ink delivery needs modifying? A converter or cartridge is air tight, just less volume.

 

[hooked]

following along, although I don't plan on making an eye dropper.
I'm not following why the ink delivery needs modifying? A converter or cartridge is air tight, just less volume.

What I have read and heard discussed in the podcast is that it's more about airflow. Having the second hole in the housing allows 2 spaces for the air and ink to go through so that both are not fighting for the same space.

If you are sealing the back and front of the section with o-rings the "nipple" is the only spot for ink to go down to the nib, but also the only opening to allow air into the reservoir to equalize the air pressure when affected by things such as the heat from your hand. If you drill a small .5mm hole on the flat area of the housing next to the nipple it allows ink to flow out through the nib while also allowing the air to flow in at the same time helping to relieve the burping and priming problems you can encounter with an eyedropper fill pen.

 

[TDahl]

I am heading toward trying this myself when I have some time to experiment. I had the same plan with the O-rings, silicone grease, and ensuring my threads are tight. I am curious how the funnel shape will help with ink flow. It is a cool idea. Please post your results.

In one of the As the Pen Turns podcast episodes, Jonathon Brooks discusses how he drills a tiny hole in the nib housing at the top to improve ink flow. They touch on it at the beginning of episode 31 if you want to check it out. In an earlier episode, he goes into more detail, but I can't remember which one.

Hi Mark,

I heard the same episode (I think the later one) which gave me the idea. If I remember right I think Jonathon mentioned about chamfering the hole to help guide the ink sort of like a funnel. That is what gave me the idea. I measured the dimensions of a 2.5 pilot bit which should work for the nipple on a Jowo #6 nib. I will post updates on how well it works.

 

[hooked]

I found the longer discussion on eyedroppers. It is an unnumbered episode between 19 and 20 (Title: 30% More). It starts at about minute 51.

 

[TDahl]

What I have read and heard discussed in the podcast is that it's more about airflow. Having the second hole in the housing allows 2 spaces for the air and ink to go through so that both are not fighting for the same space.

If you are sealing the back and front of the section with o-rings the "nipple" is the only spot for ink to go down to the nib, but also the only opening to allow air into the reservoir to equalize the air pressure when affected by things such as the heat from your hand. If you drill a small .5mm hole on the flat area of the housing next to the nipple it allows ink to flow out through the nib while also allowing the air to flow in at the same time helping to relieve the burping and priming problems you can encounter with an eyedropper fill pen.

The airflow issue is a concern I have, and I am not sure I have completely wrapped my head around the cause and the solution yet. I do remember hearing about drilling a hole in the housing, but I am not understanding where exactly to drill. I have heard it explained several times, but I am still not visualizing exact where to drill. I think I would need to see a diagram first. I am still researching this part of the process.

Great input. Thanks.

 

[TDahl]

I found the longer discussion on eyedroppers. It is an unnumbered episode between 19 and 20 (Title: 30% More). It starts at about minute 51.

Awesome. Thanks.

 

[TDahl]

following along, although I don't plan on making an eye dropper.
I'm not following why the ink delivery needs modifying? A converter or cartridge is air tight, just less volume.

Hi Patrick,

Thanks for the question. My main motivation for making an eye dropper delivery system is simply to have more flexibility in the design of the pen. I would like to make shorter pens and this I feel is one option that will allow me the flexibility to do that.

 

[d_bondi]

The airflow issue is a concern I have, and I am not sure I have completely wrapped my head around the cause and the solution yet. I do remember hearing about drilling a hole in the housing, but I am not understanding where exactly to drill. I have heard it explained several times, but I am still not visualizing exact where to drill. I think I would need to see a diagram first. I am still researching this part of the process.

Great input. Thanks.

Tim, I haven't gone back to listen again, but I seem to recall that Jonathon was saying to drill on the back of the housing above the nipple, above meaning tip side if nib. This would align with the groove in the feed, right? They suggested drilling with the nib and feed removed to reduce the possibility of damaging the feed and/or nib.

If this is right, then you wouldn't want to machine the section with a funnel down the size of the nipple as there would be no way for this drilled hole to allow air to pass.

Just my recollection though...

 

[jalbert]

I would just make sure you have good section threads and then use silicone grease. I've never done anything more for my eyedropper-able pens and haven't had any leakage issues. If you want to spend the time designing a dedicated eyedropper with o rings and whatnot though, go for it.

I'm not sure why the extra hole in the housing is needed. In my experience, eyedroppers are noticeably wetter than cartridge or converter pens, and I would not want to make them even wetter.

 

[TDahl]

Tim, I haven't gone back to listen again, but I seem to recall that Jonathon was saying to drill on the back of the housing above the nipple, above meaning tip side if nib. This would align with the groove in the feed, right? They suggested drilling with the nib and feed removed to reduce the possibility of damaging the feed and/or nib.

If this is right, then you wouldn't want to machine the section with a funnel down the size of the nipple as there would be no way for this drilled hole to allow air to pass.

Just my recollection though...

Hey David,

I just listened to the episode again (thanks Mark for locating it) and you are right. Jonathan suggested drilling a small micro (.5 mm) hole on either the right side or left side of the nipple. They also talked about using "O" rings and grease on both the section and the nib housing to completely seal the system. The funnel in my designs would cut off any area for the breather hole. I think I will stick with a normal channel through the section, and let gravity do the work with the addition of the breather hole.

Thanks for the input.

 

[TDahl]

I would just make sure you have good section threads and then use silicone grease. I've never done anything more for my eyedropper-able pens and haven't had any leakage issues. If you want to spend the time designing a dedicated eyedropper with o rings and whatnot though, go for it.

I'm not sure why the extra hole in the housing is needed. In my experience, eyedroppers are noticeably wetter than cartridge or converter pens, and I would not want to make them even wetter.

That's good information John. I might try one without the breather hole, and one with the breather hole and see what happens. Thanks for the input.

 

[PatrickR]

I have purchased several cheap Chinese pens and all of them have an o-ring on the housing and the section.
these are different brands and only one is supposed to be used as an eye dropper. I've never inked the bulk filler but will just to see how well it works.

 

[rixstix]

I think drilling holes would significantly affect the capillary balance between the ink and air channels within the feed.

Here's a link to more design info than you might care to know.. the ebook is 300+ pages. Most, if not all, of it is available in menu pulldowns too.

https://fountainpendesign.wordpress.com/

 

[TDahl]

I think drilling holes would significantly affect the capillary balance between the ink and air channels within the feed.

Here's a link to more design info than you might care to know.. the ebook is 300+ pages. Most, if not all, of it is available in menu pulldowns too.

https://fountainpendesign.wordpress.com/

Thanks Rick,

This is a great resource with a lot of information.

 

[Sean777]

I just found this article and curious on how you progressed as I'm thinking of making one and curious if you used M10/ M13 or went larger to allow more ink storage based on the ink consumption with doing copperplate script and to allow best overall design to optimize use for the customer.

 

[TDahl]

I just found this article and curious on how you progressed as I'm thinking of making one and curious if you used M10/ M13 or went larger to allow more ink storage based on the ink consumption with doing copperplate script and to allow best overall design to optimize use for the customer.

Hi Sean,

After doing a little more research and talking talking with Phil Dart from Beaufort Ink and Jonathon Brooks from Carolina Pen Company, I decided to stick with my original design and found the prototype works well. The charging time (the time it takes for the ink to flow from the body chamber to the tip of the nib) is between 10 to 20 seconds.