Answering your TWSBI Eco Questions

The TWSBI ECO was launched as a new fountain pen model back in 2015. It's been extremely popular ever since for new pen users and experienced ones alike. Previously, the TWSBI 580 was the value TWSBI pen (and still is really). But with the sub $50 TWSBI Eco coming out, and with the same ink capacity as the 580, it almost seems too good to be true.

Ever since getting the TWSBI Eco in my hands, I've been asked all kinds of questions about it. Here are some of the most frequently asked ones that you may be curious about:

Frequently Asked Questions:

What nib does the TWSBI ECO use? Can it take a nib from another TWSBI?

It appears to use the same nib as the TWSBI Classic, Mini and Mini-AL, Vac-Mini, Swipe, and Go. They're technically interchangeable, but you have to physically pull the metal nib from the grip of the pen to swap them. It's a smaller nib than what's on the 580, and the spare 580 nib unit is not interchangeable with the Eco.
There is no nib unit available for the Eco, so you must pull the nib from a whole pen in order to swap nibs (which is REALLY hard on the Classic, fyi).
There aren't many options for spare nibs in this size from other brands (none at Goulet), buying multiple Eco pens may end up being the most practical)
The fins on the TWSBI feeds are extremely fragile. Removing the feed is not recommended unless using extreme caution. Do at your own risk!

Is the grip triangular like a LAMY safari?

No, it's not. Looking at the front of the grip, you can see three protrusions that stick up to help keep your fingers from sliding off the end, but they're very small and don't carry up the length of the grip. The majority of the grip is cylindrical. If you aren't as much of a fan of triangular grips, then the Eco would be a suitable option for you.
However, there is a newer version called the ECO-T, which does feature a more triangular grip section.

What parts are swappable with other TWSBI pens?

The internal piston can swap with the 580, but then you can't post either pen. But the guts of the piston mechanism appear identical. I wouldn't call them "interchangeable" in terms of being able to actually use the parts on both models of pens, but in terms of their basic functionality, they're pretty much the same.
The nibs swap with the Mini and Classic, but you have to pull just the metal nib out, the grips don't swap.
The feed appears identical to the Classic.
The cap of the 580 can kind of fit onto the Eco, but it's not a perfect fit. I wouldn't recommend it, and they don't swap the other way around.
The o-ring at the grip threads appears the same on the Eco as the 580.

How does it compare to the TWSBI 580 and Mini?

Piston mechanism appears identical to 580.
It's about the same overall size as the 580, longer than the Mini.
Ink capacity is similar to 580, larger than Mini, pushing close to 2ml.

Where does the name come from?

ECO = Economical…more affordable pen.
It doesn't mean eco as in "eco-friendly". Y'know, any more than a normal fountain pen is eco-friendly (cuz they all kinda are).

How do you disassemble the pen?

Exact same as 580, with a different wrench (that I like better!)
Check out the 580 disassembly video I have, it'll be the same method.

The wrench is different; can they be used interchangeably with the original metal one?

Yes, they work interchangeably. The red wrench isn't super-tight on the Vac700R, but it works well on the ECO, 580, Mini, and Classic. The metal wrench works on the ECO.

TWSBI fountain pen uncapped with red TWSBI wrench

Can you use a TWSBI bottle to fill it?

Yes and no, grip does not remove, so it fills just like a normal pen would.
You can fill like any other pen from the cone insert directly in the bottle, but not from the cap of the bottle like the 580, Mini, and Classic.

How is it filled?

It's a piston pen that operates just like all of the other TWSBI pens.

How much ink does it hold?

Appears similar to 580, just under 2ml at its max.

What is the fit and finish like?

Really nice, clean, better than I expected for this price point!

How does the TWSBI ECO post?

It does not post on the filler knob, no worries about blurting ink due to twisting the knob inadvertently. It has an o-ring on the barrel of the pen, just before the filler knob, that the cap sits on to hold it in place. Posted it's a tad long, but light so it's pretty usable even if you don't have giant gorilla hands like me.