Friday, March 15, 2013

Removing Vacuum Filler Pen O-rings

I recently posted this video about unscrewing the back of your filler knob on your vacuum-filling fountain pen (such as the TWSBI Vac-700 or Pilot Custom 823, among others) so that you can ensure you get proper ink flow while you write. Understandably, some find this practice annoying. For those of you who feel that way, I give you, today's video.

Basically, you just unscrew the mechanism out of the pen, and pull off the conical o-ring on the end of the rod. This is the o-ring that seals up the ink chamber (it's separate from the o-ring that actually fits to the walls of the pen to allow it to fill), and by removing it, you bypass the need to unscrew the back of the pen altogether.

Now, realize that when you're doing this you're opening yourself up to an increased risk of leakage during traveling, especially during extreme elevation or temperature changes. These types of pens aren't necessarily more prone to this than other pens, except that any pen with a large ink capacity (2ml+) has an inherent increased risk of leaking under these situations, particularly if there is a lot of air in the ink chamber.

***WARNING*** This is probably something your pen manufacturer does not want you to do at the risk you'll do something irreversible to your pen! Be certain that you're clear about your pen manufacturer's warrantee policies, and understand that by disassembling your pen and removing a part like this, you're likely going to have to pay for any potential damage or loss of small parts that you cause, if that happens. This is a pretty simple and straightforward process, but I don't want you coming after me or the pen maker if you do something crazy to your pen while trying this. If you're not comfortable doing it, then don't!

Okay, so I got all that disclaimer mumbo jumbo out of the way there…unscrewing a vacuum filler rod from the back of pens like these and removing a small rubber o-ring really isn't dangerous or scary, the biggest risk you're likely to face is losing the o-ring, which is a unique conical shape that you likely won't be able to find anywhere if you lose it. You could also potentially cause harm if you severely overtighted the rod as you're screwing back into the pen, but that really doesn't have anything to do with the o-ring. That's just something the watch out for anytime to take out the rod and put it back in.

Usually I try to stay away from the kind of tips and tricks where I need to give disclaimers, but since I'm a retailer showing you how to go rogue on two of the pens that I sell, I thought it was safer to put them there. It's totally up to you if you decide to do this to your own pens or not, but I figured at least showing you how to do it and understanding how these pens work a little better couldn't hurt.

Write On,
Brian Goulet


  1. Halfway through the disclaimer I about turned the video off. I had a bear steal an o-ring from one of my flashlights and it was a nightmare to try to get back. I almost had to press charges. Anyways, good information to know. Thanks for sharing!

  2. Waski_the_SquirrelMarch 15, 2013 at 3:43 PM

    I won't be doing this as I like the leak prevention. However you coupled two things I love in the pen world: the Pilot Custom 823 is my favorite pen, and I have a physics degree.

    I could never quite figure out how I could raise the piston without air problems, but push it down and expel the air. The "floating" o-ring answers that question. I took the Pilot in to show my Physics class when we did our unit on pressure. A few of my students asked me to take it apart but I refused. Next year I may have to bring a TWSBI instead: it's less painful if I destroy it during a demonstration!

    Thanks for the information!

  3. I'm sorry, that must have been hard for you to watch. Angry bears stealing o-rings is a serious issue, and should be addressed by our government.

  4. I'm a bit surprised with a physics degree that you could resist the urge to take your 823 apart immediately and see how it works! It is a pretty expensive pen and they do have a pretty scary warning about how you shouldn't remove your nib or look at your pen the wrong way (okay, that's an exaggeration). You can easily take the mechanism out of the back of the pen though, and at least see how the rod is designed, without doing any damage.

  5. The pilot parts look identical to the TWSBI parts. I wonder if they're made by the same company in Taiwan or China. Brian, Did you closely compare the plungers side by side and/or try interchanging the parts?

  6. Nice video, Brian. I first saw this detailed in FPGeeks' video of disassembling the Vac700 when it first came out: http://youtu.be/nS25au7tVhA

  7. Nice video. I performed this operation on my Vac700 a while ago and haven't had a problem, almost... It is worth mentioning (again) that the pen will leak if it is upside down and tapped or slammed on a table or ... It's much more likely to spit BUT it's worth it because this pen is a fantastic pen. I choose it over a bunch of other pens because of the very fine steel nib and the great ink flow. Never skips, Always writes as soon as the nib touches paper. I did tweak my very fine nib that came with the pen that was horrible at first BUT there is free replacement nib that comes with the very fine nib. This pen even writes with the nib upside-down, to get a finer line. (With a bit of inner edge smoothing.) Get one, I have 3 and enjoy. I want to know why they don't make a translucent RED version?????


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