TWSBI Vac Mini Smoke Fountain Pen

The pen writes very nice and got a descent fill on one attempt. My issue with the pen is the threads for the piston filler are rough and hard to engage when closing (even jamming like it's about to cross thread. (I'm very gentle and careful not to let it, but I feel you can cross thread it if you force it). For a fundamental component of the pen and is used to fill it or even open the flow - the end threads should be a lot smoother.

I picked up this little guy as it's plane-friendly (I can't bear the idea of travelling without a FP). It's very solidly built and has a huge ink capacity; I bought it with the Vac20A inkwell and there's barely an air bubble in there. It's slightly larger than the 580 mini and, having small hands, I can use it posted or unposted.

I bought a medium nib as I figured that's the most versatile for travel. As with all my other TWSBIs, the writing experience is smooth. However, the flow is not terribly consistent, something I see in many reviews of this pen. It will write pretty well for about a page and then the flow chokes up and I have to jiggle the plunger and tap the nib to get it going again. This is with the plunger valve open for writing. Since this is primarily a journaling pen it's kind of frustrating. I only use very wet inks in this pen.

I love that you can buy replacement nib units, I may give the fine a try to see if that helps with the flow issues at all.