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.


  1. wow. Sounds like a great idea and would definitely like to see your make!

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