Breaking Down a Parker Vacumatic Filler Unit

One of the giants of American pen manufacturing, Parker, produced millions of pens using the vacumatic filling system. It proved to be reliable, provided for a huge amount of ink storage, but also intimidates many collectors. We hope that this complete tear-down will remove much of the mystique from this venerable but reliable piece of fountain pen hardware.

To begin with, fountain pens had sacs to hold the ink. Housed in the pen barrel, various methods were used to squish, twist, or press the air out of them, providing suction to draw up a supply of ink. In the 1930s, Parker developed the proprietary vacumatic filling system. Instead of a sac, the barrel itself housed the ink. A rubber diaphragm was installed between the ink chamber and a spring-loaded pump which, when depressed, would force air out of the chamber, creating a mild vacuum which would pull ink into the chamber. For detailed drawings, see Richard Binder’s very excellent Anatomy of a Fountain Pen II: The Parker Vacumatic

There can be, however, some confusion as to the state of the pieces. Are they glued together? Is shellac involved? Let’s look at a later-1940s filler unit, as this is often the kind encountered.

1. The Teardown

Vac-filler Teardown

This is the complete filler unit, taken from a Parker “51”. It looks pretty complicated, especially compared to simple squish-the-sac filler systems. However, when you reduce it to its component parts, it is not nearly so fearsome.

Vac-filler Teardown

Our first step is to remove the pellet socket. The plastic used in manufacturing these sockets is, sixty years later, quite brittle. Try this at home and you will likely shatter it (ours happened to be loose on the plunger.) This is the one piece glued on originally.

Vac-filler Teardown

The next piece is the retaining collar. Keep in mind that this piece floats freely on the plunger shaft/spring, and should easily come off.

Vac-filler Teardown

Vac-filler Teardown

The spring end is fit between the prongs on the end of the plunger and is not glued, but is instead kept in place by the pellet socket. Over time these prongs can lose their flexibility, causing the pellet socket to become loose; a drop of cyanoacrylate glue will hold it in place.

Vac-filler Teardown

Finally, the threaded securing screw slides off the plunger. This can be made of aluminum or, more rarely, plastic. Again, this is a freely floating piece, not attached in any way to the other pieces.

2. The Spring and Retaining Collar

Vac-filler Teardown

As a bit of an aside, let’s look at the relationship between the spring and the retaining collar. The larger-wound end is held in place simply by virtue of it’s large diameter; no glue or shellac need be applied. Occasionally it gets pulled down inside a bit, and may seem to be glued in place. It’s not, and can be gently but firmly worked loose: use a twisting motion, which will take advantage of the coiled shape of the spring to ‘unscrew’ it from it’s seat.

3. Rebuilding

Generally cleaning is just a case of giving everything a good soak in warm ammonia water. This will soften any caked-on rubber or other unidentifiable muck, and dissolve any leaked ink. Use an old toothbrush to clean out the crevices, and repeat the process until things are freely moving. A dental scaler is excellent for paring away hardened rubber from around the tapered seat on the retaining collar.

We cannot overstate the importance of thoroughly cleaning the threads of the securing screw. If any crud remains on the screw itself, in the barrel threads, or in the blind-cap threads, then the pen will likely not go back together properly. At least, the blind cap will sit askew; at worst, the diaphragm seal will be compromised and the barrel will leak. Again, we turn to the dentists: a pick is excellent for chasing threads (be careful if it is plastic!) Another option is to make a thread-chaser from an old securing screw (this trick can be attributed to Ron Zorn. I refer to mine as the “Zorn tool”.)

Once clean, the rebuild is simple: we assemble the parts in reverse order.

4. Installing the New Diaphragm

These filler units take the “debutante”-sized diaphragm. Don’t try to substitute a regular pen sac, however tempting, as it just won’t sit right. Here we have a diaphragm, trimmed to 11/8″ long.

Vac-filler Teardown

We seat it firmly in the socket using a tool which will reach up inside the diaphragm to cup the tiny ball inside. A time-honoured tool is the end of a Q-tip which has had the cotton ball trimmed off. Fancier tools can be made of 3/32 brass tubing, but be sure that it is smooth, with no sharp edges, which could damage the rubber.

Vac-filler Teardown

Vac-filler Teardown

We brush the diaphragm with 100% pure talc (and nothing but, please. The last thing you want is gummy cornstarch in the works!) Now the fiddly part: we invert the diaphragm so that it wraps back over itself. It’s stretchy and tough, so just wriggle it back over itself. Occasionally, bad words may ensue. The end should fit snug and flush against the top of the tapered bottom of the retaining collar. If there are any uneven edges, trim them with a sharp blade (you can press right into the collar, it’s tough.) You do not need to secure the diaphragm with any kind of glue or adhesive. The pressure of the securing screw pressing down on the retaining collar will keep it in place.

Vac-filler Teardown

Now check that, when you hold the pieces together and fully depress the plunger, the diaphragm is fully extended. If you trimmed it to 11/8″ it should be fine.

5. Re-installation

Re-installation is where all the parts work together: tightening down the securing screw is what holds the mechanism together, rather than glue. The first step is to lubricate the outside of the diaphragm. Don’t skip this step, as rubber is stretchy and grabby; it just won’t work without soapy water, or spit, or K-Y jelly. Take your pick.

Vac-filler Teardown

After the rubber is all slippery, gently work the diaphragm down into the barrel. Make sure, during the process, that the end stays seated firmly on the tapered retaining collar. You can easily feel when the works are in place. Using only your fingers, tighten down the threaded securing screw just until it starts to firm up. Now stop.

Reverse the pen, and look down the barrel with a bright light. Push the plunger a few times while you are looking down into the gloom. You should see the end of the diaphragm, damp but completely even, with no creases or folds. It should move smoothly when you push the plunger. If anything looks odd, loosen everything off, pull out the unit, and re-install it. Patience and humility now will save you from stains, frustration, and self-loathing later. If there are any folds or gaps when the diaphragm is tightened down, the pen may leak, fail to fill properly, or even crack when you tighten the securing screw down.

Vac-filler Teardown

Once the diaphragm is properly seated, you can tighten down the securing screw properly, using the right tool. (I’m assuming you have one, because you got the unit out in the first place.) Tighten it down so that it is snug, but not too tight. The wide portion of the securing screw should be just below the end of the barrel, like in the photo. If you tighten it too far, the excess pressure could bulge the plastic, or even crack it. Remember, any difficulty you may have had in removing it was likely because of six decades of crud and ossification.

Vac-filler Teardown

Try screwing on the blind cap. If it doesn’t feel smooth all around the circumference of the join, try tightening or loosening the unit slightly. If nothing works, take the unit out and re-chase every bit of threading you can find. Then repeat the installation process. A word of warning: should you try to sand down, or otherwise trim the blind cap or barrel to hide the unevenness, the wrath of the Pen Gods will descend, and your remains will be carried away in a small paper bag. Just chase the threads and everything will be alright.

The vac-filler unit was a brilliant invention, and is still an easily-found part of fountain pen history. A properly serviced vacumatic filler unit will last for decades. We hope this has helped to dis-spell some of the mystique of the process of restoring this simple machine, and will help those trying to preserve those that remain.

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