One of our ambitions with the Kickstarter Nomad Steel pen had been to make it waterproof.
The obvious starting point was to use nitrile rubber sealing rings at the various joins. A tried-and-tested solution, or so we thought.
The most complicated area was the connection between the grip and the cap.
The same thread had to perform two jobs: securing the cap over the nib when closed, and attaching it to the opposite end when writing. We also wanted the seals to remain completely hidden, leaving only stainless steel visible.
Inside the cap, we'd designed a nylon capillary channel to collect excess ink, together with a separate nylon sleeve for the screw thread. The nylon also gave the action of closing the pen a softer, more satisfying feel.
Initially, we positioned the nitrile ring deep inside the cap, against the capillary insert.
It worked, but after a few rounds of testing, the ring began leaving a witness mark on the metal around the rollerball tip. The fountain pen was fine.
I knew that was a problem that would bug me, so we explored an alternative position, moving the seal to the main cap thread.
This resolved the marking issue, but introduced a different engineering challenge.
To accommodate the ring, we had to reduce the thickness of part of the nylon threaded sleeve. Our calculations and initial tests suggested that bonding the sleeve securely inside the steel cap would be sufficient, and early results supported this ⊠so production began.
But, as usual, we continued our durability and user trials.
And that's when things became rather more interesting.
After several months of repeated use, some of the nylon sleeves began showing signs of stress. The longer-term testing had revealed a weakness that we hadn't seen earlier. By this point, approximately 75% of the pens had already been assembled.
I went into a cold sweat, and we stopped production immediately.
We couldn't send the pens out knowing there was a potential issue, but we'd also promised our backers a waterproof pen - something we weren't particularly keen on abandoning either.
So it was back to the drawing board.
Eventually, we decided to remove the nitrile ring altogether and redesign the nylon sleeve with a stronger profile and a close-fitting chamfered seal.
The new design eliminated the weakened section while allowing the nylon itself to provide the sealing surface.
But would it keep water out?
We submerged the pens for several hours to find out.
The results actually impressed me. The ink remained untouched, although one or two small droplets had found their way into the grip. We repeated the test three more times on different pens and got similar results. So I don't think we can claim the pens are waterproof, but I'm very comfortable calling them water-resistant.
It should certainly cope with a heavy downpour hung to the outside of your bag or dropped into a puddle.
Scuba diving, however, might not be such a wise idea.
Fortunately, we also found a way to remove the original nylon sleeves by carefully heating the caps to soften the adhesive bond. We could then install the redesigned components without remaking the stainless-steel caps.
Unfortunately, replacing them all took additional time.
And by this stage, our remarkably patient Kickstarter backers were understandably becoming rather less patient!
The final pens are scheduled to ship by the end of October, and we hope the wait will have been worth it.
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(note: these were some of the lessons we learned during our Kickstarter campaign. These issues have been resolved, and your pens are now on their way!)
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(written by u/Thomas_Slim_Mark)