A New Platypus

I have been working on a totally new fountain pen model that differs in major ways from the exisiting models 1 and 10. It will be called the Platypus Model 20.

A clutter of Model 20 prototypes

The Model 20 is not yet available, and the last details of its design are not yet final, so this announcement runs the risk of inducing the Osborne effect.  The Osborne effect is a lesson for marketers where customers hold off on buying existing models in the expectation of buying a newer model. Legend has it that the pioneering Osborne computer company went bust in the early 1980’s because people stopped buying the existing stock after more advanced models were shown in prototype form (https://en.wikipedia.org/wiki/Osborne_effect). I’m prepared to wear that possibility, but really, if you like everything about the Model 1 or Model 10 then buy one. The new model will be different in just about every way, and is ‘better’ only if you prefer the differences. It will also be a little more expensive.

The newest prototype Model 20. The final version will almost certainly look like this.

First thoughts

The Model 20 was initially going to be a simple flat-top version of the current Model 10, with a Jowo or Bock nib unit and a cartridge converter. I won’t say that it would be boring (particularly as a Model 30 might be just like that!) but it promised to be a relatively simple task for me to re-shape an already well worked design. Gradually the brief for the new model expanded into a totally new pen that differs in lots of important ways.

An early prototype for Model 20 alongside a Model 10.

One way to make the new pen stand out a bit from the current Model 10 —and from most other cartridge converter pens— was to utilise the large volume cartridge converter that TWSBI sell for their Swipe pen. (If I recall correctly, the idea was originally Michael Lampard’s. Certainly it came up in a conversation with him.)

The Swipe converter has a larger ink capacity than the standard international (about 1.3ml compared to 0.75ml) but nonetheless fits onto any nib unit that expects to be mated to a standard international converter. The Swipe converter is fatter than the standard and so it does not necessarily fit into the body or section of your conventional cartridge converter pens. It does not fit into the Platypus Model 1 and Model 10. Of course it would be an easy matter for me to make the inner dimensions of a new pen big enough. I could supply the pen with a Swipe converter inside and with an accessory adaptor collar to allow standard international converters (or cartridges) to also fit snugly.

I made a few prototypes of that pen, both with my standard patterns and a couple of new ones. A new pen, based on the Model 10, but a bit thicker to accept a slightly larger cartridge converter and with nearly flat ends. Same nib units as the Model 10, but maybe some new patterns…
On second thoughts, that doesn’t sound very challenging for me. And, for my customers, it might even exacerbate the difficulty of choosing models, patterns can colours. Hmm. Maybe I can do something a bit more interesting, and something more challenging from the design and manufacturing point of view.

Second thoughts

How about a pen that does not take a cartridge converter, a pen that has an ebonite feed? That sounds better. How about one that uses a filling system different to any currently offered by other pen makers? Interesting.

Ebonite feed

People like ebonite feeds for their excellent flow characteristics, and I can put one of them in if I move away from cartridges and converters.

To use a cartridge you need a nipple at the back of the feed that mates to the cartridge. The Jowo and Bock nib units that I have been using feature such a nipple and a corresponding extension at the end of their plastic feeds to reach up into the nipple. Ebonite feeds typically do not have such a feature and so ebonite feeds are mostly seen on pens that do not use cartridges.

A plastic feed from a #6 nib unit and a 6.35mm ebonite feed. (With a lovely Platypus Pens sticker.) Notice the part of the plastic feed that protrudes into the cartridge.

I’m not saying that every ebonite feed is incompatible with a cartridge, as there are some counter-examples. The Flexible Nib Factory offers ebonite feeds that would work with a standard cartridge (e.g. this one). Such an ebonite feed and nib housing might make a nice upgrade for a Model 1 or Model 10, but they are a bit on the pricey side given that they cost more than the whole Jowo #6 nib unit with a plastic feed and the nib. I did not consider them for the new Model 20 because I was already enthralled with the idea of a novel (sort of…) unique (sort of…) filling system that would work with a plain ebonite feed.

A novel(ish) and nearly unique filling system

Novel(ish)? Nearly unique? Well, the truth is that when I first designed the system I thought that I was inventing it. Turns out that I was re-inventing an old system, a system that appears to have died out. That makes it novel(ish) and nearly unique. (No matter what sticklers for the rules of grammar might say!)

The basic idea of this filling system is that it has a deformable portion that is compressed to blow out air and then rebounds to make a vacuum to suck up ink. Yep, like the bladder of a vintage lever-fill pen. But not exactly like that. The bladder of the Model 20 is compressed by being twisted and wrung out. It is a twist-fill system. 

Detail from a diagram in the 1903 patent for a twist-fill system for a fountain pen.
A prototype Platypus bladder being twisted.

As I’ve said, the twist-fill mechanism is not a new invention. There are many patents from early in the twentieth century relating to twist-fill mechanisms. Twist-fill fountain pens were sold by A.A. Waterman as “The Pen with the Magic Button” and versions of it were sold for several decades. Other pen makers offered their own take on the twist-fill mechanism, including Sheaffer with their 1930’s Wasp twist-fillers. An explanation of the many variations on twist-filling pens can be had at the Vintage Fountain Pen Doctor and Home of Paul E. Wirt pens & the Museum of Fountain Pen Filling Systems.

Twist-filler pens appear to have been quite popular early in the last century, but you cannot buy a new one now. Why? Well, the twist-filler mechanism offer fast and easy filling, but with an Achilles’ heel: the rubber bladders used in the twist-fill pens would eventually fail as a result of either the stresses of being wrung out, or because natural rubber bladders eventually go hard and crack. The Platypus Model 20 bladder should never crack because it is made of a very robust and stable plastic, polyurethane, and it is designed with pre-programmed flexures that minimise the stresses imposed on the material as it is being operated. 

I have tested the bladder of a prototype pen by twisting and untwisting it 100,000 times over two days using a stepper motor. At the end of the test the bladder looked and felt no different. That number of actuations is more than anyone should expect in a lifetime of regular use of a Model 20 but, nonetheless, I intend to re-run that test with even more actuations as soon as I have finalised the design of the Model 20 and its bladder.

The Platypus Model 20

The Model 20 takes a #6 sized nib and has an ebonite feed that offers excellent ink flow. It’s a twist-filler where a half turn and release of the knob will suck ink into the pen. Repeating that 4 or 5 times takes a couple of seconds and fills the pen with over 2ml of ink: more than most piston filler pens and far more than a cartridge converter holds. Like the Model 10, the new pen is middling to large in size (by modern standards: vintage pens tend to be smaller than current pens) and is fairly light and exceedingly comfortable to use. (All details are subject to arbitrary change!)

Future posts of this blog will show and discuss a range of issues relating to the choices of design and materials of the Model 20.