The Writing Desk Reference Section: Questions about pens
About TWSBI nib compatibility
Diamond 530, 540 and 580 (and variants, eg 580AL, 580RB etc)
All these models us a number 5 size nib. Although TWSBI has changed manufacturers (Schmidt for the early 530s, later Bock and now JoWo) all these nibs are interchangeable. The only difference is that the current 580 model has a different front section with a metal trim ring but the innards are essentially the same. One small caveat: the original Diamond 530 nib is slimmer in profile to the later Bock and JoWo units. This means that if you have one of these pens then a new nib may not fit in the inner cap. If you encounter this problem, we can supply a new wider inner cap.
TWSBI Diamond 530/540 nib assembly
TWSBI Diamond 580 nib assembly
TWSBI's Diamond mini uses a smaller number 5 size nib to that on the Diamond 580. The feeds and collars look the same as those on the Diamond 580 but they are in fact subtly different.
TWSBI Diamond mini nib assembly (with part of shipping container)
The Classic model uses the same nib, feed and collar as the Vac mini. Therefore, nib assemblies can be interchanged between TWSBI Classic and TWSBI Vac mini pens by removing the front section parts.
Although the Classic model uses the same nib and feed as the Diamond mini, the collar is different so Diamond mini and Classic nibs are not fully interchangeable. If you want to fit a Diamond mini nib to a Classic, the nib has to be removed from the collar together with the feed. This task is quite difficult and often results in damage to the feed.
The TWSBI Vac mini uses the same nib/feed/collar assembly as the Classic but mounted in a different front section. Luckily, as of October 2016 TWSBI produces spare nib units for the Vac mini range.
TWSBI Vac mini nib assembly
This model uses a larger number 6 size nib (manufactured by JoWo) so is completely incompatible with other TWSBI fountain pens. Larger Edison pens use the exact same nib as do models from many other manufacturers.
Early Vac 700 models used a Bock nib. These can be identified by the point size label (F, M etc) being on the side of the nib body rather than the top as is the case for the Jowo nibs.
TWSBI Vac 700 nib assembly
TWSBI Micarta pens use the same nib as the Vac 700 models but the nib is gold plated. Mark 1 pens had a Bock nib with Mark 2 models featuring a JoWo nib. Please refer to the notes in the Vac 700 section above regarding identification.
The TWSBI Eco uses the same nib and feed as the Diamond mini, Classic and Vac Mini models. However, there is no interchangeable assembly like the Diamond mini so the nib and feed have to be pulled out of the body of the pen. See the notes in the section on the Classic above regarding separating the nib from the feed and collar.