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Vac-antsy

Posted by Dirck on 29 January, 2014

I’m taking a day out from under my muse’s whip to engage in a little self-flagellation.  This was coming anyway, but a piping fresh email from a friend prompts me to act now.  The subject of the note was the TWSBI Vac 700, which he’s considering as a potential next pen (a serious consideration, as he’s one of these happy people that can get along with but a single pen), and I was reminded that I wanted to hold forth a bit on that pen, as I’ve owned one long enough now to have formed a mature opinion.  There are, in a small way, misgivings about it.

More specifically, I have misgivings about the way the filler works.  The general style is one I favour– the friend in question stated his own misgivings about relying on “explosive decompression” for function, but it is a fun and relatively efficient way of filling a pen.  In terms of user effort, it’s extremely efficient, with its quick up, in, down, done… when there aren’t problems built in.  Having many fillings under my belt now, I begin to think that TWSBI has built in a small problem.

They’re not the only ones, I should say, but they’re the only one whose current production pens I can afford.  Like some rather more exalted vacuum fillers, the Vac 700 has a Safety Cut-Off Anti-Drip Valve (which is what none of them actually call the item), an extra seal on the front of the filler shaft.  Let me get the simplified tear-down, so you can have a look at it:

It’s the little conical entity on the far left end of the filler assembly, and it’s pretty easy to see how it works.  Inside the barrel, just behind the section, there’s a depression for the seal to nestle into, and with the tail knob firmly screwed down, it prevents ink from passing into the feed.  Unscrew the knob a little, and ink passes freely.

There’s plenty of people who view this as a big pointless imposition, and I sympathize with their point of view.  It adds a step to unlimbering the pen for action, and extra steps and time are anathema in our current world.  However, since the feed holds plenty of ink once it’s been allowed to access the reservoir, it usually has plenty of reserve for a quick note, so I don’t really share the objection.  My problem with that seal comes in at filling.

Up, in, down, done.  Right.  Except, I find that if I’m a little too brisk with “down”, the seal engages even as the vacuum releases, and I get a very miserable draw of ink.  Going carefully on the “down” brings filling problems too, as the way the main piston seal in this pen works calls for constant downward pressure to hold the seal.  With an old Sheaffer, you can cock the mechanism, push down through most of the travel, and if you let go the vacuum will cause the piston to bob back up– it’s actually pretty neat.  With this rig, if you let go, you can’t even see the amount of travel in the piston required for the seal to vanish, so hesitating on the down-stroke is fatal to the filling attempt.  One thus has to put in effort enough to fit a very narrow Goldilocksian window to get a decent fill.

I have not seen a lot of others complaining about this, so it may be specific to my pen.  Possibly something to do with the little problem it had with some angry German ink a while back, or (gulp) it might be connected with my own tinkering– did I put the filler unit back together entirely properly, or did I arrange it so that there’s too much depth on the shaft?  However, I am going to do something about it, and it’s probably the stupid solution.  I’m going to pull the cut-off seal entirely.  It’s easy to get at, performs a function so redundant that “belt and suspenders” seems negligent by comparison, and the procedure is easily reversed.

…although if I was smart, I’d start experimenting with how deeply the blind cap retaining nut should sit (at this point, he descended into muttering technicalities and had to be led away by his minder).

Today’s uncomplicated pen: Sheaffer 5-30SR
Today’s ink: Pelikan Violet

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