Saturday, 13 June 2020

Telescopic Piston Filler

In the 1950's, Montblanc came up with a piston filler popularly known as the "Telescopic Piston Filler". Pens made in that era which come with this filling mechanism are extremely sought after. This was an innovative design and what I consider to be an engineering marvel. Conceptually, it is not very difficult to understand how the filling mechanism works. However, it is very challenging to implement this design. It is believed that Montblanc discontinued making them because of the production costs.

When I first saw the telescopic piston filler, I was intrigued. I decided to make my own so that I can offer them on my pens. The detail of parts involved in making this filling mechanism is daunting. With limited capability to manufacture parts (essentially a mini lathe is all I have), I had to be innovative about how the telescopic mechanism is implemented. It took me months of research and several trials and failed attempts to finally make a Telescopic Piston Filler that works.

Most of the parts of this mechanism are made in brass. As a result, it does provide substantial weight to the body of the pen. The mechanism itself weighs about 22 Grams. The piston extends beyond the barrel threads so that the seal can be replaced easily. I use a delrin nut to secure the seal in its holder.

The seal can be either made in cork or an 'O' ring holder. A cork seal has to be made carefully to ensure that it provides just enough tension inside the barrel. If it is too tight the piston will disengage prematurely. While operating the piston, it has to be backed up against the section, so that it can fully retract while being filled.

Typical ink capacity of a pen fitted with this telescopic piston filler will be about 2.5 ml. This can be increased by making a longer piston. The brass insert nut that engages with the end cap is about 12mm diameter. Because of the size of the piston filler, the resulting pens will be slightly oversized.

This was a fun and exciting experience. Hope it excites others as well.

Sunday, 13 January 2019


Presenting the IRIS: a completely hand-made pen in a Uni-body design.

Over the past few months, I have been working on a new concept inspired by the innovative pen design of Stipula's Da Vinci and the Lamy Dialog 3. These are truly engineering marvels and I wanted to attempt a creation that, if not as elegant as these two, at least comes somewhat close.  After tinkering for months, I finally have succeeded in creating a functional pen that carries most of the design elements of a Uni-body pen.

The pen does not have a separate cap. The top of the pen has an Iris aperture blade which acts as a hatch. This iris has to be operated manually using the turning knob. The nib is then extended out of the body of the pen by simply turning the end knob at the bottom of the pen's body. It takes about three turns to fully extend the nib.

Filling the pen involves removing the top section and then removing the nib holder inside. Once the nib holder is removed, the pen can be filled using its converter. The use of separate nib holder also allows the pen to be fitted with either a standard cartridge or a converter.

The IRIS can be fitted with any size 5 nib, such as Jowo, Schmidt 340 or Bock 180 nib units.

Since the pen uses an iris for closing the top of the body, there is a small opening that remains after the iris is closed. This may result in the drying up of ink. To address this issue, I have added a magnetic thimble which seal the opening and fits precisely on top of the iris. The iris blades and the housing are both ferromagnetic, so that they hold the thimble securely in place.

When the thimble is removed, it can be placed at the back of the pen where another magnet holds it in place.

The clip is made of solid Sterling silver and so is the center band. To enable flexibility of the clip, a micro-slit is cut at the bottom of the clip:

Here are the technical specifications:

Length (closed): 131 mm
Length (with nib extended): 148 mm (this will also depend on the size of the nib)
Section Width: 13.8 mm
Overall Girth: 18 mm

Saturday, 8 July 2017

The Dunnstor

The Dunn Pen company in New York made pens during the 1920's. One of the key features of their pens was the filling mechanism, which was patented at the time. It was a simple plunger based filler which worked more like a syringe filler. I had recently come across one of their models called the "Dreadnaught", which was their largest pen. These are extremely rare to find and whenever it show up for auction, it can easily fetch hundreds of dollars. I like different filling mechanism and I wanted to recreate this pen in my own way. So, here it is:

For this first prototype, which I am calling the "Dunnstor", I used materials that were easily available and also helped highlight the key features of this pen. The barrel is made of clear acrylic. The plunger itself is made of black ebonite and it is completely closed on the other end making it totally leak-proof. It has dual "O" rings that provide the best possible vacuum for pulling in ink. The simple plunger mechanism is operated by the knob at the bottom of the barrel. A few strokes of the plunger fills this pen up to an ink capacity of slightly more than 2.5ml. I think the ink capacity can be further increased by reducing the size of the plunger.

The end knob and plunger is guided by a simple stopper made in ebonite. This also secures the plunger and stops it from being pulled out of the barrel:

Another key feature of this pen is the cap itself. While filling the pen, the plunger itself has to be operated several times, which may result in an accidental damage to the nib. To avoid this, the top half of the cap unscrews to reveal an ink window for filling:

This ink window protects the tip of the nib from hitting the ink bottle while filling. The downside is certainly staining of the cap which I believe has to be washed every time the pen is filled. However, the section always remains dry because of the inside stopper.

One of the modifications I made was the addition of a silver band at the seam to make it invisible.

This kind of a filling mechanism requires nib assembly with long breather tube through the feed so that air can go out during the down stroke of the plunger. It is difficult to add a breather tube to the standard nib assemblies designed for cartridge/converter type filler. For this, I chose a nib assembly from Kanwrite which now makes 14K gold nibs with Ebonite feeds. This is a screw in type nib assembly but has a breather tube at the bottom of the feed instead of the C/C filler spigot. These nibs are available in many tip sizes, starting from Extra-Extra fine to Bold.

Here are the overall specifications of this pen:

Length: 160mm (can be customized)
Uncapped: 142mm
Barrel Diameter: 15mm

I am looking forward to making this as one of my standard models.

Thursday, 2 March 2017


Hello Folks!!!

What started as a weekend hobby for me about three years ago has now become my full time profession. Thanks to all of you who have supported my passion for pens. Crafting each pen by hand, one pen at a time, is certainly a time consuming activity. With all the variations in material, shape, nibs, silver bands, clips etc. makes it even more challenging. Although, I enjoy making every one of them.

This activity came to a temporary halt on February 17th when I developed a heart condition which needed immediate medical attention. I am glad that I was able to get the medical treatment in time and be able to recover. Due to the severity of the condition, I have been told to take rest for a few more days, until I can resume the pen making activity.

I know that many of you have been waiting for weeks and months for their pens. I hope that I find a way in the future to deliver more quickly and efficiently while maintaining the same quality.

Thanks once again for all your support and patience. I can't wait to get back to work and fun.

Sunday, 9 October 2016

Fast Track order processing update

It has only been 4 months since the Fast Track order processing was launched and many of you have availed the Fast Track option so far. As a result though, the regular orders have been pushed back and many of you have been waiting for upto 5 to 6 months now for your pen. Knowing that there is only so much I can do to speed things up, I felt that there was a need to make a change which will benefit everyone.

In the modified system, Fast Track orders will be placed after every 2 regular orders. This will still allow the Fast Track orders to be processed within a reasonable amount of time, while making progress on the regular orders.

I have a lot of loyal customers and Thanks to all of you, that base is growing. I would be more than happy to introduce a loyalty based points system, wherein, your order can be bumped up once you accumulate a certain number of loyalty points. This will require more work from me and coordination with all of you. I may not be ready for it yet, but this is something to look forward to in the future.

Friday, 22 July 2016

Important Update: New Presentation Boxes and Packaging

All Fosfor pens so far have been offered with a presentation box. The latest boxes were made from MDF material which was laser cut. It was an innovative approach, but had it's own pitfalls: 1) the boxes were fragile and were getting damaged in transit and 2) making them was a time consuming process.

To address the above, I have now switched to professional boxes. This is what the new presentation box looks like:

These are single pen boxes with lacquered exterior and velvet interior. They are strong enough to protect the pen inside. They have a magnetic lock so that the box doesn't open inadvertently. Every box is engraved with the fosfor logo.

Apart from this, I have also added the option of telescopic packaging. This is a cost-effective approach aimed at providing the best value in situations where a presentation box is not required.

Here is how these options are going to work:

  1. All pens going forward will be shipped with Telescopic packaging.
  2. Worldwide shipping will be reduced to $9 for Telescopic packaging. Those who may have made the purchase online will get a refund once your order is processed.
  3. The presentation box will be offered at an additional price of $6.99.
  4. Worldwide shipping will continued to be offered at $12 with the Presentation box.

Sunday, 22 May 2016

Launching -> Fosfor Fast Track & Order Tracking

Thanks to all the pen fans around the world, there has been an overwhelming response so far. This has kept me busy not only in the pen making activity, but also in responding to messages across various online channels, including emails. Many of you are curious about when your pen will be ready. This ends up creating more work for me to respond to those messages and takes time away from the pen making activity. So, in order to help achieve best results, I am launching two programs: 1) Online Order Update and 2) Fosfor Fast Track.

1) Online Order Update

This is a log of all the confirmed orders I have received so far. I will be updating this log on a weekly basis. This order log will be available online. Only a brief description of the pen will be provided in this log. An estimated start will be indicated. It will also indicate the order that I am currently working on. Most of you will be able to locate your order in this log. However, I will start communicating individual order numbers soon.

2) Fosfor Fast Track

As evident from the order list, the wait time for some you may be beyond what you'd expected. Hence, I am launching a new program called "Fosfor Fast Track". This will essentially allow you to get your pen made quicker. A detailed description of how this program works is provided on the new ordering page. Those who are interested in participating in this program, please email me and I will take care of you.

I am hoping that this will help streamline the communication and make it easy for you to follow-up on your orders.

Here is a link to both the programs: