This pen was bought specifically for modding, after reading several reviews from people who have successfully hacked some pretty cool nibs onto their pens. Here we go:

Other than having the odd creaky-piston moment, my 580AL works very well, and at under £50 due to Christmas sales, it was a bargain indeed. I got mine from Bureau Direct, who managed to get it to me in a couple days despite the seasonal mail crunch.

The stock nib is a #5 Bock, which I ordered in medium. I’m sure it’s very good and smooth like others have said, but the truth is that I never inked it up. The whole unit is made to be swappable with other Bock units, but the nib and feed are also friction-fit. So I pulled it out and stuck in a spare FPR flex nib that I’d got at their last sale, and it wrote pretty well, though I did have to deepen the ink channel just a little for the feed to keep up with the flexing.

My final aim was to house my vintage Mabie Todd nib for greater ink capacity and less mucking around with eyedroppering a fragile 100-year-old specimen. But the feed was far too long; Mabie Todd’s #2 is significantly smaller than Bock’s #5 (or Pilot’s #5 for that matter). To this end I was inspired by Leigh Reyes’s amazing post, and though she didn’t post a step-by-step or anything, she described her process enough for me to dare to replicate it. The cost of messing up a feed is the same as buying another TWSBI nib unit, so I wasn’t overly worried — plus at that point I already had experience modifying my far more expensive Pilot Custom feed!

From the picture above it’s easy to see how much shorter and slimmer the vintage nib is compared to the stock nib and the #5.5 FPR flex nib. As such I had to shorten the feed by about 1.5mm and shave it down so that its tip would be the same thickness as the uncut version. This was to prevent the feed touching the paper when I flexed the pen. And of course the ink channel needed more deepening and scraping out, which I did very very carefully. You have to err on the side of extreme caution, because there’s no going back once you’ve gone too far!

And I was rewarded with this beauty:

The demonstrator look is excellent, and easily being mistaken for a vape is hilarious. (I consider this a feature, not a bug.) It is well built for its price, and its customisability is incredible. The included wrench obviously encourages one to tinker as well!