A simple cartridge converter fountain pen that is convertible into a ballpoint or rollerball pen that takes fountain pen inks. A small and comfortable maker pen for $100 Australian. Model 3 is supplied with either a nib or a rollerball unit along with the ballpoint refill and its adaptor pieces. To have both the nib and the rollerball unit costs an extra $15.
The Model 3 is the seventh commercially released pen in the Platypus Pens lineup and incorporates advanced features that make is possible to provide an interesting high quality pen inexpensively.
The switch between fountain pen nib and rollerball unit is simple because the Schmidt units share dimensions and threads. Just unscrew the nib and screw in the rollerball and you are good to go. (Yes, you will have to make sure that the cartridge or converter is inserted and prime the unit if it is dry, but, well, it’s easy.) To switch in the ballpoint refill, remove the cartridge converter and nib, screw the black adaptor point into the front of the grip (it has separate threads from the nib and rollerball units) and insert the refill from the other end.
The first Model 3 review
Michael Lampard has recently published his review of the Platypus Pens Model 3 fountain pen and rollerball. You can see the review on YouTube here.
Advanced Features
There are only a few notable features with this pen as it is a small and simple pen.
Body-section threads: The body joins the section with a sharply tapered semi-buttress thread to maximise the strength of that vital joint that is sometimes a weak point.The taper means that the male threaded part of the section has thickest walls close to the grip and the female threads in the body are thickest where the body pattern starts; those are the places where the stress of threading on the body are highest. The semi-buttress thread form is used the maximise the thread strength and to overcome the tendency of a tapered thread to ride up and slip.
You will probably not notice the advanced form of those threads, but they do substantially reduce the number of turn needed to fully engage the threads. The full 5mm of 1mm pitch threads of the Model 3 section to body joint are completely engaged in just a couple of twists of the body. Yes, that is not really an important advantage, but it is interesting.
Fully lined cap with triple start threads: The Model 3 cap is fully lined, like all Platypus Pens models. The type of plastic used for that lining means that the cap threads are close-fitting, smooth, and relatively wear-resistant. The cap threads are not tapered, but the thread has a triple-start so that a single turn will unscrew the cap.
Hidden roll-stop design: You might think that it is the seven facets of the cap and body that provide the Model 3 roll-stop function, but you’d be mistaken. When the pen is inked the pen balances on the bumpy central cap band and near the end of the body where the facets are narrow. The roll-stop feature is provided by seven sinusoidal swellings hidden in the bumpy cap band.
Advanced toolpaths for a stronger body: Unlike previous Platypus Pens models, the body of the Model 3 is constructed of a single piece. Where previous models had thin walls and required a lining, the walls of the Model 3 body are relatively thick and they are printed with a special toolpath (i.e. the route traversed by the printing nozzle as the wall is constructed) that gives interlocking perimeters for extra strength.
Colours and patterns
At the moment the Model 3 is being made only in the vaulted panels pattern. That pattern was first devised for this pen, but has been added as an option for the Model 20 or 21 pens as well. Other patterns will likely be added in the future, but probably not this year.
The unlined body of the Model 3 relies on the inter-layer adhesion of the plastic for its strength. The advanced toolpaths used in printing the body increased that strength noticeably, but nonetheless I am not offering the super-shiny “silk” filaments like PolyAlchemy Elixir as main colours because of their limited interlayer adhesion strength.