Titanium ring whose jewels glow through induction

Ben Kokes wanted to give a ring to his sweetheart, and to make it interesting, he decided to create a ring with an inductive loop that would cause the stones to light up when they were close to a power-source. He documented the tricky technical problems that cropped up during the build, and it sounds like the romance part came out well, too:

The final idea was to embed a LED and copper coil assembly inside the titanium ring, illuminating it from under the stones when it was in close proximity to an induced alternating magnetic field (henceforth called 'the transmitter'). Autodesk Inventor helped me develop all of the dimensions and constraints for the design. Having some help, I was able to obtain her ring size and the rest of the measurements were based from there (15.72mm if anyone was wondering)...

... Of all the challenges presented in making the ring, affixing the stone is the most difficult. Traditionally, stones are affixed by mechanical means -- prongs, groves or snaps. Epoxies will delaminate from the attachment surfaces due to microstresses, thermal cycling, and other unmentioned movements. The stone may be attached now, but eventually it will fall out. It's just a matter of time.

With that in mind, I had 4 initial ideas for affixing the stone: thermally expanding the hole, hole deformation, point expansion deformation, and epoxy. Ultimately, I went with the epoxy method for attaching the stones.

The first test was to try and heat the ring, expand the hold and drop in the stone. When the hole cooled and contracted, it would hold the stone in place. Not only does the hole not expand enough, if I was lucky enough for it to happen (it did once), the stone would fracture along pre-existing crack lines.

Project Longhaul (via Hacker News)


    1.  So, basically it has to glow when you get close.

      (And before you say when I get close, that, good sir, would have to be enchanted to detect TROLLS!) =P

  1. Wow!  That is quite the instructable.  I figured it would be a challenge to make such a ring, but I had no idea how involved it would be.

  2. So the stones are going to fall out?  He went on an on about the various attachment methods including epoxy (they fall out over time), and then decided to go for the epoxy route anyway?  

    I’m a little surprised he went with titanium, as it is notoriously difficult to work with, especially for jewelery. 

  3. WOW.

    What an amazing tribute of his love.

    And an ultra cool, super fun, and gorgeous ring!!!!!

    She’s a lucky girl.

  4. I’m a goldsmith and I sometimes incorporate niobium into my work. Your ring is a very interesting item, and I applaud both the creativity and the workmanship. 

  5. All sorts of ‘you light up my life’ clichés spring to mind. Which is, of course, very fitting :)

  6. So it’s a mood ring, but the only moods are “alive” and “dead.”

    1. “Do not approach the person gripping the HV line if their ring is still glowing”.

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