I recently posted this video about unscrewing the back of your filler knob on your vacuum-filling fountain pen (such as the TWSBI Vac700R 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 overtightened 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.