Fountain pen thoughts: TWSBI Diamond 540/580
I often see TWSBI fountain pens recommended to new fountain pen users as a good, inexpensive pen. Many are sold with silicone grease and a wrench, all have instructions for filling and cleaning, and they have a number of nib options. The ink capacity is large, and TWSBI offers warranty support. Which many users discover that they need.
The pens are constructed of a fairly heavy, brittle plastic. The tool and instructions imply that you can open the pen and service it, but for many it is too easy to over tighten and break a pen. You won’t service your own pen? Even so, your pen may still develop cracks.
I’ve owned three TWSBI Diamond 540/580 pens, and all three developed cracks at one point or another. Mine were on the cap or section, and I found that a redesigned pen or warranty repair parts were just as likely to crack as not.
Against my better judgment I purchased a TWSBI mini, and time will tell how that fares. But in general, I recommend folks reconsider TWSBI pens and look for something more reliable.