The Kaweco Sport Flex Mod Failure Report

I was browsing the internet when I stumbled upon this lovely post on Fountain Pen Network by andymcc who modified a Fountain Pen Revolution flex nib to fit in a Kaweco Sport. Renderboy was able to do it to five other Kaweco Sports, so I figured I had a pretty good chance. Unfortunately for me, my attempt was a failure.

Tools Used

  • 1 Old Fountain Pen Revolution Flex Nib (all silver type)
  • Knife sharpening stones
  • 2000 Grit Sandpaper

The Modding

Andymcc said he needed to take off the a bit of the back end of the FPR nib to fit in the Kaweco Sport. I figured the best way to go about this was to put the Kaweco nib on top of the FPR nib then use a permanent marker to colour in all the areas I need to grind off. Once all the permanent marker is gone, I know I should stop grinding. The coarse grinding stone was a great choice as it made fast work of the nib. Once I had it down to size, I rounded off the edges a bit with the smoother Arkansas stone and then removed the burrs with a curled piece of sandpaper. All good so far.

I decided to go for broke based on andymcc’s experience and just put the nib on the Kaweco Sport right away. It was definitely a tight fit, but the bigger problem was the nib and the feed refused to sit tight enough together to write. Cue an hour of trying to adjust the nib so it would sit closer to the feed without success.

Figuring Out What Went Wrong

I tried a ton of things to try to coax the nib to sit nicely on the feed, I figure either the shape of the nib or the curve of the nib is off. I decided I’d go a little high tech to see if the FPR and the Kaweco nibs were similar in shape. I uses some photo editing software to get a really accurate comparison.

FPR-Kaweco-Nib-Overlay
Red overlay – Kaweco Sport Nib

As you can see from the overlay, the shape of the nibs are quite similar, so the overall nib shape isn’t the issue here. So that leaves me with the curve of the nibs. The Kaweco curve is definitely more aggressive, sitting close to the feed. The FPR nib flares out away from the feed.

What I’ll be Doing Next

So now the big question is how best to change the curve to the shape I need. Based on a clip from the show How It’s Made on fountain pens, the punched out nib is curved into the desired shape with a hydraulic press and a mold. Unfortunately, I have neither, so my solution will have to be a little more creative. I’ve attempted to use a nylon ball link pliers to force the nib to curve, but the FPR nib is small enough to slip right through. Using regular pliers to squeeze the size didn’t give me enough control on the curve either. So I think the next thing to try will be to find a metal rod with the same dimensions as the feed and attempt to hammer the nib to the right curve, maybe with a little heat to soften the metal. If you have other ideas to shape the nib, feel free to leave them in the comment section below!

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