Sunday, 17 March 2013

Kaigelu 316 Plunger Filler: Introduction

The follow on project to the vacumatic jumbo Hero 616 is complete! To disambiguate before the starter's pistol: This mod retrofits a modern Kaigelu fountain pen with a vintage Sheaffer or Onoto style single stroke vacuum plunger filler, not the unrelated Parker multistroke ink~pump with a similar sobriquet, as was the focus of last year's Hero based undertakings.

"Yes please."

This nib always makes me smile!
With TWSBI's release of the Vac700 last year, and the resurrection of Onoto's Magna, plunger fillers are currently a hot topic among fountain pen afficionados. As with Parker's vacumatic, there is a mountain of information available detailing the workings of this venerable design (the first Onoto plunger filler made its debut in 1905), as well as a surprisingly recent innovation that does away with the need for specialist seals.

Such a depth of detail brings the concept within an amateur's grasp; armed with a fistful of browser bookmarks, I couldn't resist trying my hand. This mod junks the Kaigelu's workaday cartridge/converter for the compelling gadgetry of a vacuum plunger filler!

In a departure from the spirit of the Hero 616 button filler and vacumatic conversions, for this project, I've adopted a more upmarket, "cash-rich, time-poor" ethos. Having said that, once installed, future servicing should be inexpensive as well as expedient.

The end result is a Kaigelu 316 with a more interesting filling system, increased ink capacity, and a more neutral balance in
 the hand. I've embedded a short demonstration clip of the completed pen below:

 The 316 Plunger Filler in action.

Quite pretty pens, these Kaigelus.

Why a Kaigelu this time around?
  • Wow factor - if you're going to build a plunger filler into a modern cartridge pen, why not do it with some style! As a writer it backs up good looks with dependable performance. The 316 model is a decent Duofold doppelgänger, and the smooth two-tone nib even comes with medium tipping as standard. The one weak link is its problematic cartridge converter, which I can't get along with. This £14 beauty deserves a more interesting ink filler!
  • I'm no mathemagician, but I suspect there's some sort of churlish golden ratio involved in building a working vac plunger (vacuum cylinder volume to release chamber volume, chamber volume to section feed volume and so on ad tedium). The Kaigelu 316 is huge, with a lot of space within the barrel to work with. We're talking "PFM point gasket as shaft end seal" huge. So I figured "touch wood and throw lots of space at it". The Kaigelu has space in spades!
  • Unlike Hero's 616, the barrel is roughly cylindrical, which helps in retrofitting any reciprocating-seal ink filling system tremendously.
  • The barrel wall thickness is positively Theodesian. I could bore into it for the mounting of interior circlips and hollow out the bottom vacuum release chamber without concern.
  • The blind cap comes ready made! The end finial on the pen comes from the factory as a separate piece. This factor alone makes for a great time saver.
  • The weight of the vacuum filler's extra brass and stainless steel helps alleviate the Kaigelu's wildly top heavy factory balance. Well, a bit.

A charcoal Kaigelu 316 on ice.

The subheadings below are pretty much in order of the build as it took shape, I think it makes for a fresher read to preserve a scatterbrained vérité in the write up of this mod. A Haynes manual style rearrangement of the component assembly would whiff of an omniscience that was entirely absent.

This Introduction - Scroll down for some more glamour shots of the finished pen, or click a subheading to skip ahead.
Parts and Tools - A list of everything used to make up the vacuum plunger filler and install it in the Kaigelu.
Prepping for Surgery - Discarding excess metal from the section and finial to max out the space available.
The Plunger Rod - Outfitting a brass rod with a pascal-variegating Goossens spindle.
Shaping the Seals - Turning down rubber seals to custom fit the Kaigelu.
The Packing Unit - Cutting the barrel's packing unit mounting grooves, making up the packing unit, and installation.
The Expansion Chamber - Hollowing out the lower barrel's vacuum release chamber.
The Blind Cap - Securing the blind cap to the plunger rod, and making up a snap ring for opening and closing it.
Further Mindthots - A few thoughts on future improvements, things I would do differently in hindsight, and so on.
Thanks, No Thanks! - Sources that aided this cartridge to plunger filler mod, and setbacks that hindered the project.

Photo Gallery
Here's some more photographs of the finished Vac316 to round off this introductory post. Click any thumbnail to zoom in.

One last picture before we roll up our sleeves - of the amazing pen that started it all!

Onoto poster courtesy of The Onoto Pen Co Ltd

Next time on Flounder's Mindthots...
Parts and Tools used in the customisation of this Kaigelu.


  1. Fantastic! Many thanks for posting the video.

  2. I love this mod! You're a genius, Flounder :) Thanks for the post.

  3. Thank you for posting this up for us all. It's a thing of beauty indeed. Enjoyed the process and the result. Not much more is as satisfying in this world as recreating the things you love go make them all your own. Cheers, Novella N.


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